No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Evolution of reproductive structures and functions in primitive angiosperms (Magnoliidae)
... Sporadically, free stigmatic secretion was observed in female flowers, but no insects were observed to consume it . These authors suggested that the presence of a dry stigma would be the plesiomorphic condition for the basal angiosperms, and that a protonectar based on stigmatic secretions evolved independently and along early diverging lineages (e.g., Annonaceae; Endress, 1990;Austrobaileyaceae;Endress, 1990;Chloranthaceae;Tosaki et al., 2001;Magnoliaceae;Allain et al., 1999;Monimiaceae;Endress & Lorence, 1983;Winteraceae;Gottsberger et al., 1980;Thien, 1980;Lloyd & Wells, 1992). This protonectar produced by wet stigmas was believed to be a relictual reward that evolved before the first nectar glands (Endress & Igersheim, 2000), although recent evidence calls into question whether the wet-type stigma was the plesiomorphic condition in angiosperms (cf. ...
... Sporadically, free stigmatic secretion was observed in female flowers, but no insects were observed to consume it . These authors suggested that the presence of a dry stigma would be the plesiomorphic condition for the basal angiosperms, and that a protonectar based on stigmatic secretions evolved independently and along early diverging lineages (e.g., Annonaceae; Endress, 1990;Austrobaileyaceae;Endress, 1990;Chloranthaceae;Tosaki et al., 2001;Magnoliaceae;Allain et al., 1999;Monimiaceae;Endress & Lorence, 1983;Winteraceae;Gottsberger et al., 1980;Thien, 1980;Lloyd & Wells, 1992). This protonectar produced by wet stigmas was believed to be a relictual reward that evolved before the first nectar glands (Endress & Igersheim, 2000), although recent evidence calls into question whether the wet-type stigma was the plesiomorphic condition in angiosperms (cf. ...
... As a whole, extant basal angiosperms have bisexual, protogynous, fragrant, generalist flowers with no nectaries; in addition, floral thermogenesis is widely distributed (Thien et al., 2000;Endress, 2001b). Coleoptera and Diptera are the primary pollinators and wind also seems to be important (Thien et al., 2000;Bernhardt et al., 2003; but see Endress, 1990). ...
... Typically, the males invest more resources for flowering (male floral display), while the females relatively do so more for fruits and seeds (Delph 2009). In animal-pollinated unisexual flowers, larger male floral displays are the result of pollinator-mediated selection and ensure pollinators visitation for better mating opportunities (Eckhart 1999). On the other hand, among the anemophilous unisexuals, greater investment in male function (profuse pollen production) increases the chances of mating. ...
... This is a probable compromise to overcome the cost of daily and continuous flowering along with inefficient pollen dispersal/low pollinator availability (Harder and Thomson 1989;Mangla and Tandon 2014). Similarly, dimorphism among the unisexuals commonly exists for flower size; staminate flowers are usually larger than pistillate, for example, Sagittaria latifolia, Ecballium elaterium, etc. and animal-pollinated unisexuals from the temperate regions (Eckhart 1999;Yakimowski et al. 2011). ...
Evolution of dioecy among plants is a distinct phenomenon, debated extensively among biologists. It has now been realized that besides the underlying gender determination mechanisms, it is equally important to understand the contextual framework of eco-evolutionary forces that are instrumental in shaping dioecy in general. The theoretical framework of evolution of dioecy is well-argued in literature. Several empirical studies have indicated ecological factors like habitat, floral features, wind pollination, and clonality to be advantageous for establishing dioecy. Further, resource partitioning among genders is known to modulate the sex ratios, which is crucial for its evolutionary maintenance. How these factors influence evolutionary pathways and evolution of dioecy, has not been sufficiently investigated. Available phylogenetic analyses indicate that the factors are interlinked, and that they serve as usual correlates of dioecy. Although, such associtations are not clearly elucidated in literature due to paucity of information about the prevailing sexual systems, further obscured by low species richness in existing dioecious clades. In this chapter, we present a conspectus of present understanding of ecological correlates of evolution and maintenance of dioecy, especially among the flowering plants. The information which has emerged so far indicates the involvement of multivariable eco-evolutionary suites. However, in order to appropriately characterize them, there is need to extend empirical studies on the complete range of sexual variation.
... Although angiosperm flowers vary greatly, the perianth is usually the showiest part of the flower that attracts pollinators. In basal angiosperms, the innermost perianth series can be elaborated with nectariferous auricles, lateral appendages, cucullate bases, and food bodies (Endress 1990(Endress , 2001Endress and Matthews 2006). In eudicots, petals are often brightly colored and sometimes elaborated with marginal lobes, adaxial lobes, elaborate tips, invaginations, and localized hair pads (Ronse De Craene 2002;Endress and Matthews 2006;Vaes et al. 2006;González and Rudall 2010). ...
... Although angiosperm flowers vary greatly, the perianth is usually the showiest part of the flower that attracts pollinators. In basal angiosperms, the innermost perianth series can be elaborated with nectariferous auricles, lateral appendages, cucullate bases, and food bodies (Endress 1990(Endress , 2001Endress and Matthews 2006). In eudicots, petals are often brightly colored and sometimes elaborated with marginal lobes, adaxial lobes, elaborate tips, invaginations, and localized hair pads (Ronse De Craene 2002;Endress and Matthews 2006;Vaes et al. 2006;González and Rudall 2010). ...
Premise of research. The Iris flower is considered to be a pseudoinflorescence by having three pollination units, each acting as a labiate flower. The sepal provides the entrance, “floor,” and “walls” of the pollination tunnel and is sometimes adaxially elaborated with various structures, such as ridges, crests, and protuberances. Crested sepals have a prominent median crest that lies along the proximal-distal axis of the pollination tunnel and sometimes also have various lateral structures on the entrance, floor, or walls of the pollination tunnel, suggesting that they may play a role in pollination. Crested sepals are morphologically diverse and have evolved at least five times in Iris. Understanding their micromorphology and anatomy will shed light on the diversification of perianth and provide insights into flower-pollinator interaction. Methodology. Micromorphologies of the adaxial epidermis and anatomical characteristics of selected crested sepals representing different patterns of structural elaborations as well as ridged and nonelaborated sepals were studied using scanning electron microscopy and light microscopy. Pivotal results. Compared with nonelaborated sepals, the occurrence of the median and sometimes lateral structures on crested sepals changes not only the architecture of the pollination tunnel and its entrance but also the epidermal topology within the pollination tunnel by creating new epidermal zones. Compared with ridged sepals, crested sepals have a more sophisticated median structure that is usually more prominent and elaborated at the pollinator entrance and/or the distal half of the pollination tunnel. Vascular tissues and trichomes are also present in or on some of the median and lateral structures. Conclusions. The micromorphologies and anatomical features of crested sepals are diverse even though convergences in terms of epidermal topology and the occurrence of vascular tissues in elaborate structures also occur among independently evolved crested lineages in Iris. Structural elaborations may provide optical and tactile cues or stimuli to pollinators.
... However, whether there are floral scents and anther and stigmatic secretions in A. trichopoda requires investigation. In general, basal angiosperms show insect pollination systems emphasizing beetles (Coleoptera) and flies (Diptera), while thrips (Thysanoptera) and bees (Hymenoptera) are more likely to play secondary roles, and wind pollination is noted as uncommon to rare (Endress, 1990(Endress, , 2001Thien et al., 2000). ...
... Each female flower usually contains 0 to 4 staminodes and 3 to 9 spirally arranged carpels. The number of floral organs in both female and male flowers is highly variable, a pattern common to the ANITA grade and other families of basal angiosperms (e.g., Magnoliidae sensu Endress, 1990). ...
The shrubs and small trees of Amborella trichopoda are functionally unisexual and the populations are dioecious,male biased, and occur primarily in clumps. Floral size dimorphism reported for this species was confirmed by differences in floral biomass. At the level of the inflorescence, there were significantly greater numbers of male versus female flowers/inflorescence. No differences were observed between male and female plants in height, stem number, and diameter at the ground level. Male flowers bear 6 to 21 stamens and female flowers 3 to 6 spirally arranged carpels and staminodes that mimic the fertile androecia in male flowers. Flowering within a population was synchronous, and flowers of Amborella trichopoda are both insect-and wind-pollinated. A wide variety of insects ranging in size from ca.1 mm to 7 cm in length pollinate the flowers, indicating a generalist pollination system. Beetles involved in pollination dwell in the forest litter but also spend hours on the leaves, flowers, and branches feeding on pollen. Pollen is the reward for insects as there is an absence of detectable floral volatiles and nectars, and anthers lack secretions or food bodies. A free-flowing stigma secretion was occasionally present, but it was not consumed by pollinators. Structural studies indicate that the stigma is of the dry-type, and the pollinators probably visit female flowers because of the mimetic role of the staminodes. The combination of wind and insect pollination exhibited in A. trichopoda is rare in basal angiosperms. Gall midges, parasitoid wasps, and thrips utilize floral tissue as a breeding site, impeding reproduction. Two species of gall-inducing midges (Cecidomyiidae) insert egg(s) into the gynoecia of developing flower buds, converting one or more ovaries into galls. Parasitoid wasps (Chalcidae) lay eggs in the galls that develop into larvae that prey upon the midge maggots. The Cecidomyiidae expanded with the angiosperms, but the earliest fossils of gallinducing gall midges occur in the Miocene. Deceptive mechanisms involving numerous floral traits in small bisexual and unisexual flowers are common in the ANITA group and other basal angiosperms.
... The interpretation of the berry as one of the original fruit types of angiosperms has been repeatedly discussed, based on analysis of reproductive structures of different groups of angiosperms (Gottsberger et al., 1980;Endress, 1983Endress, , 1990Endress, , 1996Romanov, 2004;Romanov et al., 2006;Romanov and Bobrov, 2008;Endress and Doyle, 2015). Insofar as the fruit is the interpolation and continuation of the carpel, the berry hypothesis is potentially interconnected with the recognition of the ascidiate (peltate) carpel as the ancestral type and subsequent development of an indehiscent fruit due to the lack of the development of a suture (e.g., Leinfelner, 1969;Endress and Igersheim, 2000a;Endress, 2004). ...
Premise
The representatives of the ANA‐grade of angiosperms demonstrate a diverse pattern of morphological characters, but their apocarpous gynoecium (except in Nymphaeaceae), composed of at least partly ascidiate carpels, the four‐nucleate and four‐celled female gametophyte, and the diploid endosperm (except in Amborella ) are inferred to be plesiomorphies. Since the structure of fruits in Austrobaileyales is under‐investigated, this research aims to fill this gap in these data, describing the carpological characters of ANA‐grade taxa, and potentially illuminating the ancestral fruit and seed types of angiosperms.
Methods
The pericarp and seed coat anatomy was studied with light microscopy. The character optimization was carried out using WinClada software.
Results
The fruits of Austrobaileya, Trimenia, Kadsura and Schisandra are determined to be apocarpous berries of the Schisandra type, with a parenchymatous pericarp and mesotestal ( Austrobaileya ) or exomesotestal seeds (other genera). Most inferred scenarios of fruit evolution
indicate that the apocarpous berry is either the most probable plesiomorphic fruit type of all angiosperms, or that of all angiosperms except Amborellaceae. This suggests the early origin of the berry in fruit evolution. The plesiomorphic seed type of angiosperms according to reconstructed scenarios of seed type evolution was either a seed lacking a sclerenchymatous layer or an exotestal seed.
Conclusions
The current research indicates that an apocarpous berry, and not a follicle, is a probable plesiomorphic character of the ANA grade taxa and of angiosperms as a whole.
This article is protected by copyright. All rights reserved.
... (Chevallier 1996, Kelly & González 2003 and includes up to 400 species (Gon zalez & Stevenson 2002, native to the tropical, subtropical, and temperate zones of the Northern and Southern hemi spheres (Kharkevich 1987, Gonzalez & Stevenson 2002, Kelly & González 2003. The genus is represented by vines, shrubs and rhizome herbs (Endress 1990, 1994, Razzak et al. 1992. Some species of the genus are relics of the Paleogene flora (Tertiary relicts) (Kurentsova 1968, Adams et al. 2005, Gonzaloález et al. 2014 and local endemic to different regions, for example, A. delavayi Franch. ...
Plants of the genus Aristolochia L. are included in the pharmacopoeias of different countries because they have a high potential as anti-inflammatory, bactericidal, wound healing agents, and antidotes and their spheres (fields) of medical application are diverse. Due to the depletion of natural populations, the renewal of the species by biotechnological methods has become relevant. In vitro reproduction or clonal micropropagation enables the researchers to massively duplicate plants with a definite genotype throughout the year. This review provides important information available today on the in vitro propagation methods and further successful regeneration for valuable plants from the genus Aristolochia. The generalized information is necessary to create a breeding technology for each of the species of the genus, which will save valuable medicinal resources.
... Fleshy fruits are common in extant flowering plants attracting different frugivores, such as mammals and birds. While Early Cretaceous angiosperm seeds are described as tiny, thin-walled, and without any distinctive biotic dispersal features, Aptian-early Albian floral assemblages from Portugal contain a high proportion of fleshy fruits (drupes and berries) (Eriksson et al., 2000) resembling the fruits of extant basal angiosperms, such as Amborella and most Austrobaileyales, magnoliids, and Chloranthaceae (Endress, 1990). These early fleshy fruits were presumably dispersed by reptiles as well as early birds and mammals (Eriksson et al., 2000) and could have exhibited dormancy (Forbis et al., 2002). ...
The Early Cretaceous palynological successions record one of the earliest waves of angiosperm radiation in several low-latitude localities, including the Arabian Plate. The palynological analysis of 59 core and cuttings samples from the late Barremian–early Aptian Biyadh and Shu’aiba formations, offshore Saudi Arabia, reveals remarkably high angiosperm diversity. These Early Cretaceous angiosperms inhabited northeastern Gondwana together with a diverse flora that also included bryophytes, lycopodiopsids, ferns, conifers, and other gymnosperms. A review of the dispersal capacity of this Gondwanan flora suggests that most mainland taxa had potentially colonized the carbonate islands and island arc archipelagos on both sides of the Neotethys Ocean. Two models are postulated to explain the late Barremian–early Aptian radiation of angiosperms. During sealevel lows, angiosperms would be easily dispersed to carbonate islands contiguous to northeastern Gondwana. Early birds and flying reptiles acted as the main dispersal agents for the early flowering plants, together with a diverse set of abiotic factors. The sub-aerial exposures of oceanic seamounts would serve as stepping-stones for early birds and flying reptiles, allowing a two-way dispersal of angiosperm propagules to distant volcanic islands. During sea-level highs, angiosperm gene flow between the mainland pool and the island inhabitants would be severely impeded because of the drowning of the coastal regions, many carbonate islands, and seamounts, thus promoting insular allopatric speciation and adaptive radiation. During these periods of geographical isolation, the remaining emergent Neotethyan archipelagos would act as ‘insular centers of diversification’ generating angiosperm island endemics, which in turn would be dispersed to the mainland during the following sea-level lows. Additionally, the gene flow of early aquatic angiosperms colonizing the scattered water bodies on northeastern Gondwanan wetlands would be limited during sea-level lows, turning these sites into ‘wet centers of diversification’.
... Although syncarpy is widespread among angiosperms and often cited as a key evolutionary innovation, it is very rare within Annonaceae: complete syncarpy has previously only been reported from the sister genera Isolona and Monodora (Guédès & Le Thomas, 1981;Couvreur et al., 2008;Couvreur, 2009). Two contrasting hypotheses have been developed to explain the evolution of syncarpy (Endress, 1990): the "multiplication hypothesis," in which the gynoecium is initially reduced to a single carpel, but with a subsequent increase in carpel number due to branching of the carpel primordium; and the "fusion hypothesis," involving congenital fusion of separate carpels. Developmental studies of the gynoecium in Monodora crispata (Leins & Erbar, 1982) revealed similarities with that of a single carpel, supporting the former hypothesis. ...
Potential key functional floral traits are assessed in the species‐rich early divergent angiosperm family Annonaceae. Pollinators (generally beetles) are attracted by various cues (particularly visual, olfactory and thermogenic), with pollinators rewarded by nectar (generally as stigmatic exudate), heat and protection within the partially enclosed floral chamber. Petals sometimes function as pollinator brood sites, although this may be deceptive. Annonaceae species are self‐compatible, with outcrossing promoted by a combination of protogyny, herkogamy, floral synchrony and dicliny. Pollination efficiency is enhanced by pollen aggregation, changes in anthesis duration, and pollinator trapping involving a close alignment between petal movements and the circadian rhythms of pollinators. Most Annonaceae flowers are apocarpous, with syncarpy restricted to very few lineages; fertilization is therefore optimized by intercarpellary growth of pollen tubes, either via stigmatic exudate (suprastylar extragynoecial compitum, EGC) or possibly the floral receptacle (infrastylar EGC). Although Annonaceae lack a distinct style, the stigmas in several lineages are elongated to form ‘pseudostyles’ that are hypothesized to function as sites for pollen competition. Flowers can be regarded as immature fruits in which the ovules are yet to be fertilized, with floral traits that may have little selective advantage during anthesis theoretically promoting fruit and seed dispersal. The plesiomorphic apocarpous trait may have been perpetuated in Annonaceae flowers since it promotes the independent dispersal of fruit monocarps (derived from separate carpels), thereby maximizing the spatial/temporal distance between seedlings. This might compensate for the lack of genetic diversity among seeds within fruits arising from the limited diversity of pollen donors.
This article is protected by copyright. All rights reserved.
... While traits such as organ number and phyllotaxy are considered highly plastic, this is less often the case for fusion of floral organs (Endress, 1990). Despite the seemingly high rate of independent origins and losses, fusion has generally proven itself to be phylogenetically informative, leading to the classification of lineages such as the asterids which are defined by a sympetalous corolla tube (Takhtajan, 1964;Cronquist, 1981). ...
Highlight As a key developmental innovation leading to diversification in floral form, the fusion of floral parts is considered critically as an integration of pattern and process. Abstract Throughout the evolution of the angiosperm flower, developmental innovations have enabled the modification or elaboration of novel floral organs enabling subsequent diversification and expansion into new niches, for example the formation of novel pollinator relationships. One such developmental innovation is the fusion of various floral organs (synorganization) to form complex structures. Multiple types of floral fusion exist; each type may actually be the result of different developmental processes and has likely evolved multiple times independently across the angiosperm tree of life. The development of fused organs is thought to be mediated by the NAM/CUC3 subfamily of NAC transcription factors, which mediate boundary formation during meristematic development. The goal of this paper is to (1) introduce the development of fused floral organs as a key 'developmental innovation', facilitated by a change in the expression of NAM/CUC3 transcription factors, (2) provide a comprehensive overview of floral fusion phenotypes amongst the angiosperms, defining well known fusion phenotypes and applying them to a systematic context, and (3) summarize the current molecular knowledge of this phenomenon, highlighting the evolution of the NAM/CUC3 subfamily transcription factors implicated in the development of fused organs. The need for a network-based analysis of fusion is discussed, and a gene regulatory network responsible for directing fusion is proposed to guide future research in this area.
... While traits such as organ number and phyllotaxy are considered highly plastic, this is less often the case for fusion of floral organs (Endress, 1990). Despite the seemingly high rate of independent origins and losses, fusion has generally proven itself to be phylogenetically informative, leading to the classification of lineages such as the asterids which are defined by a sympetalous corolla tube (Takhtajan, 1964;Cronquist, 1981). ...
Throughout the evolution of the angiosperm flower, developmental innovations have enabled the modification or elaboration of novel floral organs enabling subsequent diversification and expansion into new niches, for example the formation of novel pollinator relationships. One such developmental innovation is the fusion of various floral organs (synorganization) to form complex structures. Multiple types of floral fusion exist; each type may actually be the result of different developmental processes and has likely evolved multiple times independently across the angiosperm tree of life. The development of fused organs is thought to be mediated by the NAM/CUC3 subfamily of NAC transcription factors, which mediate boundary formation during meristematic development. The goal of this paper is to (1) introduce the development of fused floral organs as a key 'developmental innovation', facilitated by a change in the expression of NAM/CUC3 transcription factors, (2) provide a comprehensive overview of floral fusion phenotypes amongst the angiosperms, defining well known fusion phenotypes and applying them to a systematic context, and (3) summarize the current molecular knowledge of this phenomenon, highlighting the evolution of the NAM/CUC3 subfamily transcription factors implicated in the development of fused organs. The need for a network-based analysis of fusion is discussed, and a gene regulatory network responsible for directing fusion is proposed to guide future research in this area.
... In the evolutionary history of angiosperms, floral nectaries first appeared in Nymphaeales (Fig. 7) [105,[113][114][115][116]. The floral nectaries of early angiosperms [105,[115][116][117]. Although other early-branching lineages as Amborellales, Austrobaileyales, and Chloranthales are pollinated by insects, no floral nectaries have been reported so far in those orders [111,[113][114][115][118][119][120][121][122][123] Annonaceae, Magnoliaceae, and Schisandraceae in Magnoliales); however, nectary location and structure are quite diverse, including petal nectaries, large glands on the base of filaments, and stigmatic nectaries (Fig. 7) [14,105]. Septal nectaries are widespread in monocots, although absent in the largest family -Orchidaceae (Figs. 7 and 8a) [14,99,113,[124][125][126][127]. ...
... The flowers of all known species of Aristolochia bear a gynostemium (as in Orchidaceae and Stylidiaceae; González & Stevenson 2000;Suárez-Baron et al. 2016). Furthermore, the flowers are protogynous: stigmas mature and wilt before anthers release pollen (Endress 1990, Judd et al. 2008). The plants can be self-compatible or not, but the temporal separation of the female and male function appear to minimize self-fertilization (see data in Sakai 2002). ...
A review of the literature at large and the field photographic record of the senior author of this study indicate that there are several undescribed species of Aristolochia in Hispaniola (Dominican Republic and Haiti), related to A. bilobata. Here we show that A. mirandae is a synonym of A. bilobata and that what appears as A. bilobata in Marión H. (2011: 76-77) is a new species here described as Aristolochia adiastola. In addition, two new species, A. bonettiana and A. marioniana, also related to A. bilobata, are described and illustrated herein. Resumen Una revisión extensa de la literatura existente y de los registros fotográficos en campo del primer autor indican que hay varias especies no descritas de Aristolochia en Hispaniola (la República Dominicana y Haití). Aquí demostramos que A. mi-randae es un sinónimo de A. bilobata y lo que aparece como A. bilobata en Marión H. (2011:76-77) es una especie nueva aquí descrita como Aristolochia adiastola. Otras dos especies nuevas de Hispaniola, A. bonettiana y A. marioniana, también relacionadas con A. bilobata, son aquí descritas e ilustradas.
... The flowers of Nymphaeaceae bear a central nectary on the petals, while the flowers of Cabombaceae produce nectar through glandular trichomes [105,[115][116][117]. Although other early-branching lineages as Amborellales, Austrobaileyales, and Chloranthales are pollinated by insects, no floral nectaries have been reported so far in those orders [111,[113][114][115][118][119][120][121][122][123]. Nectar is margins [9,14,99]. ...
... The flowers of Nymphaeaceae bear a central nectary on the petals, while the flowers of Cabombaceae produce nectar through glandular trichomes[105,[115][116][117]. Although other early-branching lineages as Amborellales, Austrobaileyales, and Chloranthales are pollinated by insects, no floral nectaries have been reported so far in those orders[111,[113][114][115][118][119][120][121][122][123]. Nectar is produced in most of the families of magnoliids (e.g., Winteraceae in Canellales; Aristolochiaceae in Piperales; Lauraceae and late Monimiaceae in Laurales; Evolution of floral nectaries. ...
... The flowers of Nymphaeaceae bear a central nectary on the petals, while the flowers of Cabombaceae produce nectar through glandular trichomes [105,[115][116][117]. Although other early-branching lineages as Amborellales, Austrobaileyales, and Chloranthales are pollinated by insects, no floral nectaries have been reported so far in those orders [111,[113][114][115][118][119][120][121][122][123]. Nectar is margins [9,14,99]. ...
Floral glands that produce substances related to the attraction and reward of pollinators are crucial for the reproductive success of angiosperms. These structures may include nectaries, osmophores, elaiophores, and resin glands and are quite diverse in flowering plants. This chapter presents the diversity of morphologies and substances produced by the floral glands and how they improve the pollinator’s attraction. We also describe how some angiosperms and floral visitors may have coevolved leading to specific pollination systems in some groups of plants. The integration of morphological, chemical, and
ecological studies allows for a better understanding of the relationships that evolved between flowers and pollinators along their evolutionary histories. These comprehensive approaches provide opportunities to dissect the evolution of secondary metabolites produced by specialized secretory structures in flowers, including the origin and subsequent modification of these glands and their produced compounds.
... Generally, for apocarpous flowers, once the pollen tubes penetrate the surface of the stigma, they are restricted to individual carpels without the possibility of fertilising ovules in other carpels (Carr and Carr 1961). Conversely, in syncarpous gynoecia, pollen tubes germinating in the stigmatic tissue of any one carpel can access the ovules of other carpels via the compitum, which is a pollen tube transmitting tract shared by all or several carpels of the flower (Carr and Carr 1961;Endress 1982Endress , 1990. Thus, syncarpy is often thought to enable more regular pollen tube distribution and intensify pollen tube selection, and confers a significant advantage in terms of offspring quantity and quality compared to apocarpy under uneven pollination conditions (Endress 1982;Armbruster et al. 2002). ...
The fusion of carpels into a unified compound gynoecium is considered a dominant feature of angiosperm evolution and it also occurs by postgenital fusion during the gynoecium development in some apocarpous species. However, we found the reverse process, the separation of carpels from combined carpel primordia, during the development of the gynoecium in Phytolacca. Semithin sectioning and scanning electron microscopy were utilised to observe the structure and development of the gynoecia in Phytolacca acinosa and Phytolacca americana, fluorescence microscopy was utilised to observe the pollen tube growth in the gynoecia of the two species, and the topology method was applied to analyze the relationship between the gynoecium structure and pollen tube pathway. Although the gynoecia of P. acinosa and P. americana are both syncarpous, the degree of carpel fusion in the mature gynoecia of the two syncarpous species is different as a result of variant developmental processes. However, change in the degree of carpel fusion during the development of gynoecia in Phytolacca does not affect pollen tube growth because of the existence of the extragynoecial pollen-tube pathway. Thus, the change in the degree of carpel fusion in Phytolacca is primarily the result of diversification of developmental processes related to selection pressure.
... The most widely accepted hypothesis still is that early angiosperms are pollinated by 'generalist' insects and tend to have 'generalized' pollination systems [2,5,[19][20][21][22]. 'Generalized' pollinators are animals that forage on several Table 1. ...
Insect pollination in basal angiosperms is assumed to mostly involve 'generalized' insects looking for food, but direct observations of ANITA grade (283 species) pollinators are sparse. We present new data for numerous Schisandraceae, the largest ANITA family, from fieldwork, nocturnal filming, electron microscopy, barcoding and molecular clocks to infer pollinator/plant interactions over multiple years at sites throughout China to test the extent of pollinator specificity. Schisandraceae are pollinated by nocturnal gall midges that lay eggs in the flowers and whose larvae then feed on floral exudates. At least three Schisandraceae have shifted to beetle pollination. Pollination by a single midge species predominates, but one species was pollinated by different species at three locations and one by two at the same location. Based on molecular clocks, gall midges and Schisandraceae may have interacted since at least the Early Miocene. Combining these findings with a review of all published ANITA pollination data shows that ovipositing flies are the most common pollinators of living representatives of the ANITA grade. Compared to food reward-based pollination, oviposition-based systems are less wasteful of plant gametes because (i) none are eaten and (ii) female insects with herbivorous larvae reliably visit conspecific flowers.
... Although there are many reports of early-divergent angiosperms with visible stigmatic exudate (e.g. Endress 1990Endress , 2001), the functional interpretations of this have recently been reappraised: many lineages that were previously regarded as having wet stigmas are now regarded as dry, including those in the "ANITA" grade (Amborellaceae: Hydatellaceae: Prychid et al. 2011;Cabombaceae: Galati et al. 2016;Nymphaeaceae: Heslop-Harrison and Shivanna 1977;Illiciaceae: Koehl 2002;Schisandraceae: Lyew et al. 2007;Trimeniaceae: Bernhardt et al. 2003) as well as the Chloranthales ( Hristova et al. 2005) and magnoliids (Heslop Harrison and Shivanna 1977;Pontieri and Sage 1999). Variation in stigma type is evident within the Magnoliales: although the Magnoliaceae (Heslop Harrison and Shivanna 1977) and Eupomatiaceae ( Endress 1984) similarly possess dry stigmas, other families in the order are clearly wet and often with copious stigmatic exudate (e.g. ...
Although 'dry-type' stigmas are widely regarded as ancestral in angiosperms, the early-divergent family Annonaceae has copious stigmatic exudate. We evaluate three putative functions for this exudate: as a nutritive reward for pollinators; as a pollen germination medium; and as an extragynoecial compitum that enables pollen tube growth between carpels. Stigmatic exudate is fructose dominated (72.2%), but with high levels of glucose and sucrose; the dominance of hexose sugars and the diversity of amino acids observed, including many that are essential for insects, supports a nutritive role for pollinators. Sugar concentration in pre-receptive flowers is high (28.2%), falling during the peak period of stigmatic receptivity (17.4%), and then rising again towards the end of the pistillate phase (32.9%). Pollen germination was highest in sugar concentrations < 20%. Sugar concentrations during the peak pistillate phase therefore provide optimal osmolarity for pollen hydration and germination; subsequent changes in sugar concentration during anthesis reinforce protogyny (in which carpels mature before stamens), enabling the retention of concentrated exudate into the staminate phase as a pollinator food reward without the possibility of pollen germination. Intercarpellary growth of pollen tubes was confirmed: the exudate therefore also functions as a suprastylar extragynoecial compitum, overcoming the limitations of apocarpy.
... The open suture is a condition thought to be plesiomorphic, and occurs in some primitive living dicots and palms (e.g., Degeneria, Drimys, and Chamaerops) (Eames, 1961). Carpels with solitary orthotropous ovules are also known in the Amborellaceae, Chloranthaceae, Piperceae, and Saururaceae, considered to be some of the most primitive living angiosperms (Endress, 1990;Taylor, 1991). A manuscript by Axsmith's request on these reproductive structures is in preparation. ...
Pannaulika triassica Cornet, n. gen. et. sp., a dicot-like leaf, is described from late Carnian lacustrine black shales of the Dan River/Danville basin of North Carolina and Virginia. Associated bicarpellate receptacle, achene, and multicarpellate spike are also described. A probable anthophyte affinity is based on comparisons with living and/or extinct ferns, pteridosperms, and anthophytes. It is considered to have had an upland tropical origin. -from Author
... Holostylis и Euglypha – монотипные роды трав, встречающиеся в Южной Америке (Huber, 1993 ). Среди 350 видов рода Aristolochia встречаются лианы, кустарники и корневищные травы (Endress, 1990Endress, , 1994 Razzak et al., 1992), произрастающие в тропической, субтропической и умеренной зонах всех континентов, за исключением Австралии (Жизнь растений, 1980; Харкевич, 1987; Kelly, González, 2003 ). На территории России из приведенных здесь родов представлены только род Asarum и род Aristolochia. ...
The book is dedicated to two rare plants, representatives of the ancient family Aristolochiaceae, occupying a transitional position between monocots and dicots. As many relics kirkazons contain a very rich set of secondary metabolites, whose chemical research is not yet completed. In this book the reader will find information about the biology and systematic position of Aristolochia manshuriensis and A. contorta and their close relatives, the problems of conservation of these plants in the nature and development of the cultivation of isolated kirkazon cells. Important sections of the book are devoted to the study of the mechanisms of the kirkazon action on cardiac function in normal animals and in those with artifi cial myocardial infarction. A description of a new drug created on the basis of cultured cells of A. manshuriensis is also given.
The book is intended for a wide range of specialists: botanists, geneticists, ecologists and scientifi c community, as well as other readers who care about the history of our region and the species inhabiting it.
... With respect to pollination biology, extant basal angiosperms exhibit quite remarkable diversity, having flies, thrips, beetles, moths, cockroaches and even bees as pollen vectors (e.g. Gottsberger 1974Gottsberger , 1977Gottsberger , 1988Gottsberger , 2012 Gottsberger et al. 1980; Thien 1980; Thien et al. 1985; Bernhardt & Thien 1987; Endress 1990 Endress , 1994 Endress , 2010 ). Several members are wind-pollinated or the wind is an additional vehicle besides insects . ...
... With respect to pollination biology, extant basal angiosperms exhibit both abiotic (rare) and biotic pollination; the most remarkable diversity is found among the latter wherein flies, thrips, beetles, moths, cockroaches and even bees have been found to act as pollen vectors (for reviews see e.g. Gottsberger 1974, 1977, Thien 1980, 2009, Bernhardt & Thien 1987, Endress 1990, Bernhardt 2000. Abiotic pollination is rare among basal angiosperms and several members are wind-pollinated or wind is an additional vehicle complementary to insects. ...
An updated description of the pollination and reproductive biology of basal angiosperms is given to
show their principal associations with pollinating agents. The review considers members of the
ANITA grade, as well as some basal monocots, the magnoliids, Chloranthaceae and Ceratophyllaceae.
Morphological, physiological and behavioral characteristics of flowers and their pollinating insects
are evaluated. Based on current evidence, early-divergent angiosperms were and are pollination generalists,
even so there has been early specialization for either flies, beetles, thrips or bees. Although
there are many tendencies for development from generalist flowers to specialist ones, there are also
reversals with the development from specialist flowers to generalist ones. The earliest specialization
seems to be fly pollination. Adaptations to more recently evolved insect groups, such as scarab beetles
or perfume-collecting euglossine bees, demonstrate that several basal angiosperm lines were flexible
enough to radiate into modern ecological niches.
... Today, pollinators of nectar-producing lauralean fl owers comprise a relatively broad spectrum of bees, fl ies and beetles, but also other insects (e.g. Kubitzki and Kurz, 1984 ;Endress, 1990 ;Forfang and Olesen, 1998 ;Endress, 2010 ). Th e character combination observed in the Powhatania fl ower is found mainly in Lauraceae and Hernandiaceae , but also in Monimiaceae. ...
Genetic and molecular studies have recently come to dominate botanical research at the expense of more traditional morphological approaches. This broad introduction to modern flower systematics demonstrates the great potential that floral morphology has to complement molecular data in phylogenetic and evolutionary investigations. Contributions from experts in floral morphology and evolution take the reader through examples of how flowers have diversified in a large variety of lineages of extant and fossil flowering plants. They explore angiosperm origins and the early evolution of flowers and analyse the significance of morphological characters for phylogenetic reconstructions on the tree of life. The importance of integrating morphology into modern botanical research is highlighted through case studies exploring specific plant groups where morphological investigations are having a major impact. Examples include the clarification of phylogenetic relationships and understanding the significance and evolution of specific floral characters, such as pollination mechanisms and stamen and carpel numbers.
... As far as studied, nectar production is limited mainly to the female phase of the (at least slightly) proterogynous flower (see, e.g., Erbar & Leins 2013). Basal grade angiosperms with bisexual flowers as most members of the Magnoliids are uniformly proterogynous (Endress 1990, 1994a, b, Endress & Igersheim 2000b, Thien et al. 2000 promoting cross-pollination. It has been assumed that proterogyny is connected with unreliable pollinators since proterogyny provides the possibility of self-pollination as a back-up if cross-pollination has failed (Cruden & Hermann-Parker 1977, Thien et al. 2000. ...
This comparative study combines original results with a review of the literature summarizing our present knowledge as regards nectaries in angiosperm flowers. The focus is mainly on the basal angiosperms (ANITA or ANA grade and magnoliids) which are evaluated at the family (and genus) level. In most orders at least one genus has been studied for the first time or was re-investigated. In the second part a comparison is made with members of the core eudicots (at the order level). In basal angiosperms, in a number of families and genera nectar is offered, though not in great amounts and in addition to pollen as a reward. Nectary sites are the undifferentiated perianth, staminodes (“petals”), stamens, and carpels. Staminodial nectaries dominate. Receptacular disc nectaries are absent. As regards histology, all types of differentiation – epithelial, mesophyllary and trichomatic nectaries – can be found, the epithelial ones being the most common type of nectar secretion. The diverse structures, the rare occurrence, and scattered distribution of nectaries in the basal groups indicate convergent evolution. What is the selective advantage of nectar secretion in pollen flowers? It has been proposed (Nepi et al. 2009) that nectar provision is an adaptation to insects which were already accustomed to sugary exudates (such as pollination drops of gymnosperms). An alternative (or supplementary) approach results from the observation that nectar production is limited mainly to the female phase of the proterogynous flowers. It may be concluded (see Erbar & Leins 2013) that the nectar assures the attractiveness of the flower in the non-pollen presenting phase. In addition, during searching for the sparse nectar the insect may come into contact with each stigma thus compensating the economic disadvantage of a choricarpous compared to a coenocarpous gynoecium.
Which embryologic characters are primitive, and which are advanced, has long been a controversial issue? The comparative embryology of angiosperms and gymnosperms does not provide any useful clue. Single embryological characters are not as useful for phylogenetic and evolutionary considerations as are a group of characters. Moreover, some of the characters may be merely adaptive without any evolutionary significance. The numerous variations cause further complication. This article is devoted to (a) distribution and phylogeny of anther tapetum, (b) affinities of megagametophyte, (c) can the angiosperm embryo sac be derived from the archegonium in gymnosperms?, (d) primitive and advanced embryological features, and (e) embryological features in Magnoliiflorae s.1. and certain Liliiflorae.
Due to its ancient origin in the Permian and the high proportion of beetle-pollinated taxa within ancestral magnoliid lineages, it has been hypothesized that beetles were among the first floral visitors of the proto-angiosperms on Earth. Thus, beetle-pollinated flowers have become important model systems essential for the study of the origin and evolution of angiosperms. Under an evolutionary perspective, in this review we synthesize what is currently known about beetles as floral visitors in the family Magnoliaceae, one of the earliest extant groups of flowering plants. Nitidulidae and Scarabaeidae are the two most common groups of beetles reported in the literature as floral visitors to Magnoliaceae; however, the evidence indicates that most modern families of beetles including all the families with known taxa associated with Magnoliaceae had already originated when the latter first appeared by the end of the early Cretaceous. Hence, Magnoliaceae could have represented a newly opened ecological niche that beetles gradually colonized and exploited, possibly shifting from gymnosperm hosts. By feeding, mating and sheltering in their flower structures, beetles have played a major role in shaping the floral biology and morphology of Magnoliaceae. Protogyny, thermogenesis, floral odors and floral movements are traits that could have evolved in response to selection pressures imposed by beetles. Further studies should assess the possible role of anthophagous scarabs (subfamilies Cetoniinae, Melolonthinae, Dynastinae and Rutelinae) in the diversification of Magnoliaceae, since this event broadly coincides with the origin of those groups of beetles in the Eocene, some of which exhibit very close associations with several Magnoliaceae species.
Aspects of floral ontogeny, breeding systems, and hybridization potential for selected members of the monophyletic Polyalthia hypoleuca complex (Annonaceae) of Malesia were investigated. Complete intrafloral dichogamy (protogyny) was found in all five members examined. Further, these five tree species had flowers developing in several serial “cohorts,” the flowers of any one cohort maturing in synchrony resulting in complete intracohort dichogamy. Two modes of the timing of maturation of successive floral cohorts within an individual were observed. In the first (P. hypoleuca and P. sumatrana), the onset of stigma receptivity of successive cohorts was separated by 2 days, resulting in complete intercohort dichogamy within any given individual. This mode of ontogeny probably acts to reduce geitonogamy and stamen-carpel interference within an individual. Two distinct “sets” of trees existed in these populations. The trees of one set were functionally carpellate at times when the trees of the other set were functionally staminate. Functional status for the two sets was reversed the next day. This pattern of complete intraset dichogamy with temporally shifted sets probably leads to enhanced pollen transfer by beetles between, but not within, the sets. The second mode of successive cohort maturation involved serial cohorts that achieved stigma receptivity day after day such that staminate and carpellate phase flowers were simultaneously present in a given individual. The second mode permits geitonogamy and intraindividual, interfloral stamen-carpel interference. P. discolor, P. glauca, and P. multinervis exhibited both modes to varying degrees. In addition, autogamy was not detected for P. glauca, P. hypoleuca, and P. sumatrana. Results from manual pollination experiments are consistent with the hypothesis that P. glauca and P. hypoleuca are self-incompatible, and a bidirectional hybrid cross between these two species yielded no fruit set.
Fluorescence microscopy and histological studies have been used to show that in Illicium floridanum Ellis (Illiciaceae), a primitive apocarpous angiosperm, functional syncarpy is achieved by intercarpellary growth of pollen tubes. After pollen germinates on the separate stigmatic crests of the carpellary whorl, tubes grow within the carpels obliquely down and inward toward the central floral axis which is modified as a stigmalike “apical residuum.” In a restricted shallow region around the base of the apical residuum, some pollen tubes grow out between the unfused margins of the carpels and circumferentially around the surface of the apical residuum from where they may enter neighboring carpels. Some pollen germination and tube growth also occur on the apical residuum itself. The apical residuum with its associated unfused carpel margins acts as an extragynoecial compitum for pollen tube transfer between carpels, and, as such, is believed to represent a mechanism for increasing the efficiency of seed set. The pollen tube pathway of Illicium appears to be a primitive expression of a line of evolutionary development leading to syncarpous gynoecia through stages possibly exemplified by certain members of the Trochodendraceae (lower Hamamelididae).
Considerable effort has been spent documenting correlations between dioecy and various ecological and morphological traits for the purpose of testing hypotheses about conditions that favor dioecy. The data analyzed in these studies, with few exceptions, come from local floras, within which it was possible to contrast the subsets of dioecious and nondioecious taxa with regard to the traits in question. However, if there is a strong phylogenetic component to the presence or absence of dioecy, regional sampling may result in spurious associations. Here, we report results of a categorical multivariate analysis of the strengths of various associations of dioecy with other traits over all flowering plants. Families were scored for presence of absence of monoecy or dioecy, systematic position, numbers of species and genera, growth forms, modes of pollination and dispersal, geographic distribution, and trophic status. Seven percent of angiosperm genera (959 of 13,500) contain at least some dioecious species, and ≈6% of angiosperm species (14,620 of 240,000) are dioecious. The most consistent associations in the data set relate the presence of dioecy to monoecy, wind or water pollination, and climbing growth. At both the family and the genus level, insect pollination is underrepresented among dioecious plants. At the family level, a positive correlation between dioecy and woody growth results primarily from the association between dioecy and climbing growth (whether woody or herbaceous) because neither the tree nor the shrub growth forms alone are consistently correlated with a family's tendency to include dioecious members. Dioecy appears to have evolved most frequently via monoecy, perhaps through divergent adjustments of floral sex ratios between individual plants. Monoecy itself is related to abiotic pollination and climbing growth as revealed by multivariate analysis. Dioecy and monoecy are concentrated in the less advanced superorders of Thorne (1992) and subclasses of Cronquist (1988). The frequency of dioecy found in a local flora therefore reflects the level of dioecy in its particular pool of families as much as, or more than, local selective factors. The positive associations of dioecy with abiotic pollination and monoecy are related to floral developmental and morphological attributes, as is the negative association with bird and bat pollination; the positive association of dioecy with climbing growth is tentatively explained in terms of differential selection for optimal resource allocation to sexual function. If rapid upward growth is at a premium in climbers and if fruit set at least temporarily inhibits growth or requires the production of thicker, more slowly growing stems to support heavy fruits, it might be advantageous to postpone femaleness. If the effect is strong, this may favor male plants.
A new genus of fossil angiosperms (Spanomera gen. nov.) is established for flowers from two localities in the mid-Cretaceous Potomac Group of Maryland, eastern North America. The type species, Spanomera mauldinensis sp. nov., from the early Cenomanian Elk Neck beds, has inflorescence units with terminal pistillate, and lateral staminate flowers. The organization of inflorescences and flowers is opposite and decussate. Staminate flowers typically have five tepals: two lateral, one posterior, and two in the anterior position. Each tepal is opposed to a stamen with a short filament, dorsifixed anther, and two pairs of pollen sacs. Stamens contain pollen comparable to the dispersed pollen species Striatopollis paraneus (Norris) Singh. Pistillate flowers have two lateral tepals and two anterior-posterior tepals that are opposed to two carpels. Carpels are slightly fused basally along their ventral margins and are semicircular in outline with a long, decurrent, papillate ventral stigma. Frequently this stigmatic surface has abundant attached pollen of the Striatopollis paraneus type. Spanomera marylandensis sp. nov., from the late Albian Patapsco Formation, is similar to S. mauldinensis but is known only from isolated flowers and floral parts. Staminate flowers have four stamens with dorsifixed anthers and each is opposed to a tepal. Stamens contain pollen comparable to the dispersed pollen species Striatopollis vermimurus (Brenner) Srivastava. Carpels have pollen of S. vermimurus on the stigma. Spanomera provides further evidence of unisexual but probably insect-pollinated flowers among mid-Cretaceous, early nonmagnoliid (“higher”) dicotyledons, and is interpreted as closely related to extant Buxaceae. Characters that Spanomera shares with other taxa suggest that the Buxaceae themselves may be closely related to Myrothamnaceae and other “lower” Hamamelididae.
In the present, second part of a series of contributions dealing with unusual nectaries, certain nectarial glands occurring in seven unrelated families are described and characterized as nectarioles. This term denotes anatomically heterogeneous, few-celled, glandular modules or idioblasts displayed singly or in clusters on the surface of flowers (producing nuptial nectar) or on vegetative organs (producing extranuptial nectar). Structural equivalents of floral nectarioles in the green parts may yield other kinds of secretions.
Internet publication on Sunstar-solutions.com
In a recent review of self-incompatibility (SI) in flowering plants, Dickinson (1990) noted that ‘SI in angiosperms is probably the best defined cellular communication system in the plant kingdom. Its genetic basis is now well established, the cells involved are clearly identifiable, the time of interaction is known, and the consequences of the communication are easy to detect’. This statement may be true for the better known examples of SI in which multiple alleles of an incompatibility (S) gene control arrest of self-pollen tubes in the stigmatic or stylar regions. It is not true, however, for an increasing number of species that have been found to have ovarian or ovular arrest (Seavey and Bawa 1986). These systems of ovarian self-incompatibility (OSI) remain poorly defined but, nevertheless are likely to be evolutionarily important (Barrett 1988). The scarcity of attention given to the characterization of OSI systems has occurred in part because they were initially assumed to be uncommon (de Nettancourt 1977), a notion which Seavy and Bawa (1986) pointed out to be erroneous. Although OSI systems have been reported to occur primarily in woody species, incompatible pollen tube arrest within the ovary has now been reported for a number of herbaceous monocotyledonous and dicotyledonous species as well (Seavey and Bawa 1986). Kenrick et al. (1986) noted that the rarity of ovarian incompatibility may have been exaggerated by the preference of investigators for small, short-lived, herbaceous plants for studies of breeding systems.
A literature review of 34 families of flowering plants containing at least one species pollinated primarily by beetles is presented. While the majority of species are represented by magnoliids and basal monocotyledons specialized, beetle-pollinated systems have evolved independently in 14 families of eudicotyldons and six families of petaloid monocots. Four, overlapping modes of floral presentation in plants pollinated exclusively by beetles (Bilabiate, Brush, Chamber Blossom and Painted Bowl) are described. Chamber Blossoms and Painted Bowls are the two most common modes. Chamber Blossoms, found in magnoliids, primitive monocotyledons and in some families of woody eudicots, exploit the greatest diversity of beetle pollinators. Painted Bowls are restricted to petaloid monocots and a few families of eudicots dependent primarily on hairy species of Scarabaeidae as pollen vectors. In contrast, generalist flowers pollinated by a combination of beetles and other animals are recorded in 22 families. Generalist systems are more likely to secrete nectar and exploit four beetle families absent in specialist flowers. Centers of diversity for species with specialized, beetle-pollinated systems are distributed through the wet tropics (centers for Brush and Chamber Blossoms) to warm temperate-Mediterranean zones (centers for Painted Bowls and a few Bilabiate flowers). It is unlikely that beetles were the first pollinators of angiosperms but specialized, beetle-pollinated flowers must have evolved by the midlate Cretaceous to join pre-existing guilds of beetle-pollinated gymnosperms. The floras of Australia and western North America suggest that mutualistic interactions between beetles and flowers has been a continuous and labile trend in angiosperms with novel interactions evolving through the Tertiary.
Monocots, with ca. 65,000 species in 78 families and 12 orders as classified by the Angiosperm Phylogeny Group (Angiosperm Phylogeny Group III, 2009), have traditionally been known as a distinct assemblage from dicots within angiosperms and are now seen as a lineage that diverged from within the more basal of the angiosperm groupings. In this study, the third in a series analyzing pollen characters across the angiosperms, we illustrate the pollen morphological diversity of monocots and analyze 19 palynological and two ecological characters for 120 taxa in 71 families covering the 12 monocot orders and 16 taxa of nine orders in basal angiosperms. Pollen morphological data from previous works and our investigations were optimized onto a new maximum likelihood tree reconstructed from an existing DNA matrix of Chase et al. (2006) using Fitch parsimony, maximum likelihood, and hierarchical Bayesian analysis. From these analyses we infer evolutionary patterns in palynological characters, assess their systematic value, and investigate two aspects (pollination type and habitat moisture) of their ecological adaptation. The highest levels of pollen variation were shown to exist in the Alismatales and Commelinales, with lower levels seen in the Asparagales, Dasypogonales, and Zingiberales; the most variable characters across the phylogeny were found to be pollen outline in polar view, size, and tectum extent. We infer unambiguous plesiomorphic states for monocots and report significant transitions in character states at various levels within the monocot assemblage. Analyses of correlated evolution reconfirmed the hypothesis of an association between exine reduction (or complete loss) and habitat moisture and found significant correlations between various states of exine loss and habitat for hydrophytic–helophytic plants. The presence or absence of the exine itself was found to be more significantly correlated than individual structures, in terms of association with hydrophytic–helophytic plants. The most rapid rate of state changes in pollen characters, in the evolutionary history of monocots, is estimated to have occurred during the Albian-Turonian stage; our work may provide insights into the identification of enigmatic fossil pollen grains from this geological time.
A comparative study of the development and morphology of the perianth in 42 species of Aristolochia is presented. These species represent all the subgenera, sections, and subsections formally proposed within this genus. Additional observations on the perianth of Asarum, Saruma and Thottea are also included because perianth morphology has been crucial for the classification of the Aristolochiaceae. The results support the interpretation of the perianth of Aristolochia, Euglypha and Holostylis as a trimerous calyx. Five main types of perianth development were found in Aristolochia which differ in the degree of fusion between the perianth lobes, the direction of floral curvature, and the symmetry of the perianth limb. The interpretation of the perianth of Aristolochia as a calyx is supported in terms of position, morphology, development, and comparison to related taxa.
Die drimanoiden Sesquiterpene (+)-Bicyclofarnesol, (+)-Winterin, (+)-Isodrimenin und (+)-Confertifolin und (−)-Warburganal können ausgehend vom abietanoiden Royleanon synthetisiert werden: J. A. Hueso-Rodriguez and B. Rodriguez, Tetrahedron 45, 1567 (1989).
Apomorphic tendencies of unusual features shared by two or more families of the Ranunculanae are: early caducous sepals, congenitally closed gynoecium up to the level of the stigma (but still apically gaping after ovule initiation!), protruding diffuse placentae, transverse fruit dehiscence (in Berberidaceae and Papaveraceae); excessive number of tepal whorls (in some Menispermaceae and Berberidaceae); unisexual flowers, synandry, wet stigmas forming an external compitum (in Menispermaceae and Lardizabalaceae); elaborate nectar-flowers, pollen with tricolpate-multiaperturate series, seeds with elaiosomes (in some Ranunculaceae, Berberidaceae and Papaveraceae). Other unusual features shared by Menispermaceae and Lardizabalaceae may be plesiomorphic or apomorphic: non-peltate carpels, fleshy fruits. Thus, floral structure suggests close relationships between Menispermaceae and Lardizabalaceae as well as Berberidaceae and Papaveraceae. A floral syndrome (probably myiophilous) consisting of small, flat, open, brownish or greenish flowers with short, spathulate, often bilobed staminodes (petals) that present open nectar from their apex occurs in (more or less basal) representatives of four families (except for Papaveraceae). It may be plesiomorphic or represent a basal apomorphic tendency in the Ranunculanae.
Angiosperms are the dominant and most diverse plant group living today. They are also found in the greatest number of terrestrial ecosystems on Earth of any group of plants (Judd et al. 2002; Soltis and Soltis 2004). They provide human beings and other terrestrial animals, directly or indirectly, with the majority of their nutrition (e.g. Theissen and Melzer 2007). Much of these foods, such as fruits, nuts, seeds, and grains, are the direct products of flowers, and pollination is an essential step in their formation. Pollination biology has long been an interest of biologists and agricultural scientists (e.g. Faegri and van der Pijl 1979; Proctor et al. 1996; Aizen et al. 2009; Lonsdorf et al. 2009; Mitchell et al. 2009). However, our understanding of the early phases of the evolution of angiosperm pollination is still limited and attempts to reconstruct the history of the interactions between angiosperms and pollinators are challenging (Hu et al. 2008; Taylor and Hu 2010). Evolutionary biologists have attempted to deduce the possible histories of pollination syndromes (summarized in Taylor and Hu, 2010) based upon usually incomplete and limited early angiosperm flower fossil records (e.g. Dilcher 1979; Retallack and Dilcher 1981; Crane et al. 1986; Herendeen et al. 1995; Crepet and Nixon 1996; Friis et al. 1999, 2000, 2006; Crepet 2008), limited insect fossil records(e.g. Grimaldi 1999; Labandeira 2000, 2002; Grimaldi and Engel 2005; Ren et al. 2009), parsimony analysis (e.g. Hu et al. 2008; Friedman and Barrett 2008; Taylor and Hu 2010), investigation on pollination biology of the most basal angiosperms (e.g.Thien et al. 2009), and angiosperm pollen fossil records (e.g. Hu et al. 2008; Taylor and Hu 2010). Currently there are three hypotheses regarding early angiosperm pollination biology (Taylor and Hu, 2010).
Schisandra glabra (Schisandraceae) is a rare monoecious liana in forests of the southeastern United States. Both types of flowers are solitary in leaf axils and radially symmetrical, with eight to 13 greenish yellow to red tepals in the flower. Each male flower has five (four to seven) spirally arranged stamens forming a red pentagonal synandrous shield. Transitions between tepals and stamens occur occasionally. Each carpellate flower contains 25–30 free, spirally arranged carpels on a conical receptacle. Histological study shows that the floral apical meristem is more highly convex than the vegetative apex; both have tunica-corpus configurations. All primordia, starting with tepals, are initiated acropetally, in a continuous 2/5 phyllotaxis. Apical diameter increases greatly after tepal initiation, more so in carpellate than in staminate flowers. The apical residuum in staminate flowers expands to form the center of the staminal shield, with the stamen primordia projecting as flattened marginal extensions. The connective region of each stamen broadens markedly, resulting in wide separation of the sporangial pairs of each stamen. Just before anthesis, each connective arches outward so that the sporangia appear lateral. In carpellate flowers, the carpel primordia are initiated helically; the apical residuum forms a narrow, spinelike structure. Floral development in Schisandra is compared with that of other primitive angiosperms such as Illicium and Myristica.
Recent cladistic analyses of angiosperms based on both morphological and molecular sequence data recognize a major clade of dicotyledons defined by triaperturate or triaperturate-derived pollen (non-magnoliids/eudicots). Evidence from morphology, as well as the atpB and rbcL genes (cpDNA), indicates that extant Ranunculidae (e.g., Papaverales, Lardizabalaceae, Berberidaceae, Menispermaceae, Ranunculaceae) as well as “lower” Hamamelididae [e.g., Eupteleaceae (allied to Ranunculidae), Hamamelidaceae, Myrothamnaceae, Platanaceae, Trochodendraceae] and several other families (e.g., Gunneraceae, Nelumbonaceae, Proteaceae, Sabiaceae) are basal in this group. The earliest records of diagnostic eudicot pollen are of mid-late Barremian age (c. 126myr BP) and by around the latest Albian (c. 97 myr BP) several basal eudicot groups (e.g., Trochodendrales, Platanaceae, Buxaceae, and perhaps Circaeasteraceae, Myrothamnaceae, and Nelumbonaceae) are recognizable in the fossil record. Possible Hamamelidaceae and perhaps Proteaceae are present by the Turonian (c. 90 myr BP). Among basal eudicots, flowers are generally bisexual although unisexual flowers are also common. In some groups (e.g., Myrothamnaceae, Buxaceae, certain Berberidaceae), delimitation of the flower is not always clear and there is a more or less gradual transition between tepals and inflorescence bracts. Plasticity in floral form at this level of angiosperm evolution is predominantly encompassed by dimerous and trimerous cyclic floral organization and transitions from one to the other are common. Spiral floral phyllotaxis of numerous stamens and carpels is more or less restricted to the Ranunculaceae. The basic condition of the perianth in eudicots appears to lack differentiation into sepals and petals, and petals appear to have arisen independently numerous times from stamens. Based on the generality of its systematic distribution, cyclic floral architecture is probably basic for eudicots as a whole, and at this level of angiosperm evolution flowers with numerous, helically-arranged stamens and/or carpels (e.g., many Ranunculaceae) almost certainly reflect processes of secondary multiplication that have occurred independently many times.
Our knowledge of early angiosperm phylogeny and of flower evolution is rapidly expanding. New evidence comes from different directions, and it seems important to constantly synthesize new results from these fields. (1) Palaeobotany brought two major developments, first comparative structural and stratigraphie pollen studies (since Brenner 1963 and Doyle 1969), followed by the discovery of excellently preserved Cretaceous flowers (since Friis & Skarby 1981). (2) Development and biology of extant flowers and structure of modern pollen was studied in many living conservative groups during the same period. Application of the SEM for comparative floral development was especially helpful (since Endress 1972). The comparative study of pollen with combined SEM and TEM techniques provided a powerful approach to link extant and fossil material (since Walker 1976). Comparative pollination biology of primitive flowers in relation to floral structure brought another new dimension (since Gottsberger 1974). (3) The application of cladistic techniques facilitated the rigorous discussion on the origin of the angiosperms from other seed plants and on early angiosperm diversification (since Crane 1985, Doyle & Donoghue 1986). (4) More recently comparative molecular studies with DNA and RNA became possible due to new techniques, applied for macro-systematics of angiosperms (since Jansen & Palmer 1987).
In the flowers of many Magnoliidae, the androecium consists of numerous, spirally arranged stamens (e.g., Illicium). The androecia in the Aristolochiaceae and the monocofy-ledonous Alismatales, with paired arrangement of the first six stamens (additional stamens arising collateral-centrifugally, or collaterally, or centrifugally, or centripetally), seem to be quite different from spiral androecia. Comparative ontogenetic studies, however, reveal that the paired arrangement of stamens can be derived from the early stages of a spiral androecium following a perianth consisting of trimerous whorls. In Magnolia denudata, with whorled perianth, this pattern of six stamens is caused by a break in the basic ontogenetic spiral (precocious inception of the eighth stamen), whereas in Annonaceae (e.g., Artabotrys hexapetalus, Annona montana) the first six stamen primordia are formed simultaneously. — Based on the androecial pattern (and other features), we may perhaps assume that Annonaceae-like dicotyledons were the ancestors of the Aristolochiaceae as well as of the monocotyledonous Alismatales.
Recently discovered fossil flowers of Magnoliidae from Atlantic Coastal Plain deposits of Turonian age are considered in the context of the overall fossil record of magnoliid reproductive remains. The assemblage of fossils from these Turonian localities is diverse and affects our understanding of the history of reproductive structures in the Magnoliidae (and in the angiosperms in general). Within Piperales (sensu Cronquist 1981), they include the earliest stamens similar to those of modern Chloranthus. Turonian fossil Magnoliales document early diversity of complicated flowers with numerous spirally arranged organs and laminar stamens and also reveal diversity in Magnoliales with cupulate floral receptacles. In Laurales, there are two taxa of fossil flowers of Lauraceae, and a fossil flower sharing some, but not all, characters with Calycanthaceae. In the context of the overall Cretaceous record of angiosperms, these fossils have important implications with respect to the sequence of appearance of disparate types of floral morphology in Magnoliidae. They also reveal diversity in character complexes now associated with several different modes of insect pollination and suggest that during the Turonian, passive (e.g., wind) dispersal of seeds was important in magnoliid taxa.
John Ray in his Historia Plantarum (1686–1704) was the first botanist to recognize cotyledon number as a useful means of subdividing flowering plants (Bancroft 1914). Although Linnaeus in his Philosophia Botanica (1751) did not explicitly mention this distinction between monocotyledons and dicotyledons, it was taken up by all later botanists. In most angiosperm classifications from Jussieu (1789) to Engler and Prantl (1887–89), monocotyledons were arranged in a position intermediate between nonangiosperms and dicotyledons, indicating a lower level of organization for monocotyledons than dicotyledons. However, with the spread of phylogenetic thinking, a ranalean origin for the monocotyledons was suggested (e.g., Bessey 1893), and Wettstein’s (1901–1907) textbook was the first to acknowledge a derived position for monocotyledons by treating them after the dicotyledons.
A number of floral features of Ceratophyllum conform with the present view on primitive angiosperm flowers and may therefore support the hypothesis of molecular systematists and palaeobotanists that the genus represents the basal clade of extant angiosperms: the flowers are minute; the organ number and phyllotaxis are highly variable — spiral (Fibonacci or Lucas pattern) or whorled (3–4-merous whorls) — but there is a single carpel; the stamens are not differentiated into anther and filament; the organs surrounding the stamens or the carpel are not closely integrated into the floral architecture and they may be interpreted either as bracts or tepals. However, other simple features may still be seen as apomorphies in the context of underwater pollination, especially the lack of lignified tissues in floral organs (except for two horns on each anther).
The exploration of the origin and diversification of angiosperms has entered an exciting new era. Fresh insights and new results are rapidly accumulating from paleobotany and a wide spectrum of botanical disciplines, and an increasing number of phylogenetic models for seed plant and angiosperm relationships are being developed. Current phylogenetic hypotheses broadly support previous views that the most basal angiosperm taxa fall within a grade of organization corresponding to the subclass Magnoliidae; however, there are divergent views on the resolution of relationships within the magnoliid grade. In part, discrepancies among the results from different analyses reflect difficulties in the polarization of critical reproductive characters, which arise because of the substantial morphological gap between angiosperms and other seed plants and the absence of important angiosperm features (e.g., carpel) in their closest seed plant relatives. These problems are also compounded by the extreme floral diversity among extant Magnoliidae, which ranges from the minute and naked, unisexual, unistaminate/unicarpellate flowers of Hedyosmum (Chloranthaceae) to the large bisexual and multipartite flowers of Magnolia (Magnoliaceae).
ResearchGate has not been able to resolve any references for this publication.