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Structural and histochemical characterization of the osmophores in corollas of Asteraceae (tribes Onoserideae and Famatinantheae)
Abstract
Osmophores are engaged in scent production and differ from other secretory structures by their product, site, duration, and anatomical structure. Whereas osmophores have been well-documented in flowers of several families, they are barely mentioned in the Asteraceae. The aims of this study are to: 1) determine the occurrence of osmophores in corollas of 39 species of the tribe Onoserideae and the only species of Famatinantheae with histochemical methods; and 2) analyze the morphology and structure of osmophores in these groups. Histochemical and histological techniques revealed osmophores in the marginal and in the central corollas of Famatinanthus Ariza & S.E. Freire and Plazia Ruiz & Pav. at the apex and margin of the corolla lobes, and at the sinuses. Osmophores were confirmed following positive staining reactions for TIOFH and TIOFH3 (Neutral Red, Oil Red O, and Iodine-Potassium-Iodide); the samples reacted negatively for Benedict's test for detecting reducing sugars. The osmophores found in this study are constituted uniquely by a papillose or non-papillose epidermis, or they extend into the mesophyll forming scent glands. In both cases, they are associated to stomata and starch grains. The corollas of the other species of Onoserideae did not react positively for osmophores.
... In fact, mesophyll osmophores could contribute to detection of Ficus species by fig wasps, as has been suggested by the recognition behavior carried out around the ostiole by the pollinating wasps of F. burtt-davyi Hutch., F. sur, and F. thonningii Blume (Gibernau et al. 1998;van Noort 1989). Mesophyll osmophores have been reported in other plant families, such as Asteraceae (Katinas et al. 2020) and Fabaceae (Marinho et al. 2014), with similar functions in terpene secretion. Indeed, the location of the osmophores and the fact that they contained terpenes in our studied species are consistent with the hypothesis that they act as selective filters in the mutualistic interaction between Ficus-Agaonidae wasps. ...
... In fact, mesophyll osmophores could contribute to detection of Ficus species by fig wasps, as has been suggested by the recognition behavior carried out around the ostiole by the pollinating wasps of F. burtt-davyi Hutch., F. sur, and F. thonningii Blume (Gibernau et al. 1998;van Noort 1989). Mesophyll osmophores have been reported in other plant families, such as Asteraceae (Katinas et al. 2020) and Fabaceae (Marinho et al. 2014), with similar functions in terpene secretion. Indeed, the location of the osmophores and the fact that they contained terpenes in our studied species are consistent with the hypothesis that they act as selective filters in the mutualistic interaction between Ficus-Agaonidae wasps. ...
The syconium is the urn-shaped inflorescence shared by all species of the genus Ficus. The orifice at the apex of the syconium is called the ostiole, and it is covered by interlocking bracts. The ostiolar bracts can have different arrangements, which only allow the entry of mutualist wasps and promote reproductive isolation among Ficus species. Here, we analyze the ostiolar structures that could play a role as selective filter and therefore impact the fig-fig wasp mutualism in the neotropical Ficus sections Americanae and Pharmacosycea. Samples of syconia with pistillate flowers during the receptive phase of seven species of Ficus were examined using light and scanning electron microscopy. Tests for histolocalization of substances were employed to detect secretory activity throughout the ostiolar tissues. Our results indicated that the ostiole has two components: ostiolar bracts and the periostiolar zone. Interspecies variation in ostiolar bract arrangement in both sections studied was broader than previously reported. We report for the first time for Ficus: (i) two types of ostiolar osmophores (mesophyll and diffuse), that could be a source of volatile compounds for attracting fig wasps; (ii) colleters in the axil of ostiolar bracts, which probably lubricate and facilitate the entry of pollinating wasps into the syconial cavity; (iii) secretory trichomes around the ostiolar bracts, and (iv) syconium basal bracts (F. isophlebia) covering the ostiole, which are the first physical barrier that the fig wasps must overcome to access receptive pistillate flowers. We describe the zones that compose the ostiole, which support the hypothesis that the ostiole is a selective filter in the interactions of fig trees with Agaonidae fig wasps. We also suggest that ostiolar osmophores, colleters, the periostiolar zone, and the arrangements of the ostiolar bracts may be informative with respect to Ficus systematics.
The histochemical studies that search for osmophores differ in the protocol they follow for fixation and discoloration of the samples, and also in the type and number of stains utilized. Despite these differences, all the studies have one point in common: the use of fresh material either collected directly in the field or cultivated in botanical gardens and greenhouses. This is an obvious limitation for the studies of osmophores. Flower parts of herbarium specimens of different dates of collection and different plant families were exposed to variable times and percentages of discoloration agents and under different stains for finding if it is possible to positively test osmophores in this type of material. We obtained positive results discoloring the samples with ethyl alcohol 96° and sodium hypochlorite, and staining with Lugol, Oil Red O, and Neutral Red (TIOFH). A protocol (TIOFH3) for osmophore testing that combines these three stains into a single procedure is proposed.
The genus Aristolochia L. has a specialised pollination system based on flowers that represent traps for insects. The floral anatomy and micromorphology of the perianth were studied to detect structural characters and secretory cells that are essential for the pollination and reproduction in A. esperanzae, A. fimbriata and A. triangularis. Additionally, we identified the insects collected inside the flowers in natural populations of the north of Argentina. Our observations indicate the presence of osmophores in the limbs of A. esperanzae and A. triangularis, and in the tube of A. fimbriata, because in this last species the fimbriae probably play the first optical attraction role. The papillose cells and epicuticular waxes in the limbs and tube entrances, particularly in A. esperanzae and A. fimbriata, ensure that insects slip into the tube, and the non-secretory conical hairs of the tube, when turgid, guide the insects to the utricle. Idioblasts on the abaxial surfaces of the tubes and utricles were observed in A. esperanzae and A. fimbrita, and probably represent ethereal oil cells that protect flowers from predation. Secretion of sugar was confirmed on all internal surfaces of the utricle in the three species, and was more abundant at the entrance. The insects were diverse species of Diptera (Sarcophagidae, Muscidae, Ulidiidae, Drosophilidae and Anthomyiidae) and Coleoptera (Staphylinidae), although pollen loads on the body were only detected on specimens of Ulidiidae and Sarcophagidae.
Abstract Utricularia cornigera and Utricularia nelumbifolia
are giant, aquatic-epiphytic species of carnivorous bladderwort
from southeastern Brazil that grow in the central
‘urns’ of bromeliads. Both species have large, colourful
flowers. The main aim of our study is to ascertain whether
the prominent floral palate of U. cornigera and
U. nelumbifolia functions as an unguentarius—i.e. an organ
that bears osmophores. Floral tissues of both species
were investigated using light microscopy, scanning electron
microscopy, transmission electron microscopy and
histochemistry. Floral palates of U. cornigera and
U. nelumbifolia provide clear visual signals for pollinating
insects. In both species, the palate possesses diverse
micro-morphology, comprising unicellular, conical to villiform
papillae and multicellular, uniseriate, glandular trichomes
that frequently display terminal branching. The
most characteristic ultrastructural feature of these papillae
was the presence of relatively large, polymorphic plastids
(chromoplasts) containing many plastoglobuli. Similar
plastids are known to occur in the fragrance-producing
(osmophores) and oil-producing (elaiophores) tissues of
several orchid species. Thus, these palate papillae may
play a key role in providing the olfactory stimulus for
the attraction of insect pollinators. Nectariferous trichomes
were observed in the floral spurs of both species,
and in U. nelumbifolia, free nectar was also recorded. The
location, micro-morphology, anatomy and ultrastructure
of the floral palate of the two species investigated may
thus indicate that the palate functions as an unguentarius.
Furthermore, the flowers of these taxa, like those of
U. reniformis, have features consistent with bee
pollination
The anther osmophores of Cyphomandra diploconos Sendtner and C. hatwegii (Miers) Dunal revealed anatomical features related to the mode of secretion when studied with SEM and thin sections for OM. In both species a blister-like subcuticular space is formed on the cell summit. Volatiles are apparently released by spontaneous (and active?) rupture of the cuticle. An account on the osmophore features of Cyphomandra is presented.
The constitutive characters of plants can be structural or biochemical and play an important role in their defense against pathogens : Citrus postbloom fruit drop (PFD) caused by Colletotrichum spp. is one of the most important fungal diseases of citrus. The pathogen infects the flowers, leading to premature fruit drop and reducing citrus production. However, flower buds smaller than 8 mm long are usually not infected by Colletotrichum spp. Thus, this study investigated whether there are constitutive mechanisms in flower buds related to Colletotrichum spp. infection. We studied flower buds of 2, 3, 4, 8, 12 and 15 mm long and petals, after anthesis, of sweet orange 'Valência' using light and scanning electron microscopy and histochemistry. We evaluated the effect of volatile organic compounds (VOCs) in flowers (R-limonene and linalool) on the in vitro growth of Colletotrichum acutatum. We found that the arrangement of the epidermal papillae in the petal primordia, the occurrence of prismatic crystals and the distribution of oil glands are the main differences between buds smaller than 8 mm and buds 8-15 mm long. Osmophores at the tips of petals produced and accumulated phenols, terpenes and lipophilic compounds. Flower buds smaller than 8 mm long have constitutive structural and biochemical barriers to Colletotrichum spp infection. In addition, this is the first time osmophores are reported in citrus. Our study shows that natural terpenes of Citrus flowers inhibit the fungal growth in vitro, highlighting the potential use of terpenes for the chemical control of PFD in citrus.
Published by Oxford University Press on behalf of the Annals of Botany Company.
histological and ultrastructural features of osmophores and nectary of Bulbophyllum wendlandianum (Kraenzl.) Dammer (B. section Cirrhopetalum Lindl., Abstract The species from Bulbophyllinae are generally regarded as fly-pollinated: myophilous or sapromyophil-ous. The section Cirrhopetalum is characterized by umbellate inflorescence and elongated lateral sepals. The aim of the floral anatomical investigation (micromorphol-ogy, histochemistry, ultrastructure) in Bulbophyllum wendlandianum (section Cirrhopetalum) was the detection of secretory activity. The appendages of dorsal sepal and petals function as osmophores. The exudation is trans-ported inside vesicles via granulocrine secretion. The cuticle stretches and forms swellings on the entire cell surface. Such swellings of cuticle on the appendages of dorsal sepal and petals were not previously described in Bulbophyllum species. The nectary is located in the central groove on the adaxial lip surface. It comprises epidermal epithelial cells and few subepidermal layers.
RLIBICUNDA Y BARNADESIA ODORATA (ASmRACEAE-MmISIEAE)" I ARISTRACT: Galetto, L. 1995 Studies on nectar and nectarips in H y a h s e r i ~ ruh~cnnda and Berriorlrsta adorata (Astcmceae-Mutisiene) Dnrmtniana 33: 127-133. F h'ectnl. chemical composition and nectary anatomy are studied in two Asgentinr species oT M u t i s ~ e c r ~ . I!ynloserrs rrrhrcrandn Griseb. and B n r t ~ n d e s z ~ o d o ~ n t n Griseb. The capitulunl of H. ruhtcunda has reddish bracts ~ n d it is composed of 5-6 perfect, red-orange, nectarifcrous flow-ers. On the other hand, B. odoroto capitulum has greenish bracts and whlte, perfect, dinlo]-phic flowers; only the 8-central flowers are nectnrrfcrous mhilr the several peripheral ones do not have nrctaries. Nectnr sugar composition is rich in hexose in I3 odorata and rlch in sucrose in 13. rrrh~crtndo. AlknloitIs, phenols, reducing acids, lipids and nmino acids were not detected in nny sampk. In both species, the nectnry is r ~ l o l e d to the upper portion of thc ovary. Its base is sup-plied with the ovarian vnsculor bundles Thc upper nectary pnrt~on surrounds the stvle base and shows many stomata ant! has na special vasctrlnr bundles. Hummingbirds S a p p h n .rynrganura (Lesson) and CIzlorostiEhnn nrireoventris (D' Orbigny e t Lafresnn,vc)-were seen visiting thr! capitul~ o f rJ. rrihrcanda i n t h r studied population. The white florvrrs of 3. odoratn prot!ucs a
A synopsis of Plazia Ruiz & Pav. (Onoserideae, Asteraceae) is presented, including the description of a new species, Plazia robinsonii M.O.Dillon & Sagást., from a locality c. 20 kms west of Huamachuco, Department of La Libertad in northern Peru. It most closely resembles Plazia conferta Ruiz & Pav., a narrow endemic from central Peru some 450 km to the south; however, the latter species has larger leaves and smaller capitula. Plazia is a small genus of four species confined to the Andean Cordillera of Peru, Bolivia, Chile, and Argentina. A distribution map of the four species, an illustration of the new species, a photograph of the holotype, and a key to species are provided.
Nine species of birds - seven hummingbirds (Trochilidae) and two Passeriformes - were observed visiting the flowers of Erythrina speciosa Andrews (Fabaceae), a hummingbird-pollinated species present on the campus of Londrina State University, Paraná State, Brazil. Nectar in bagged flowers bore little relationship with nectar in flowers opened to foragers either regarding quantity or diurnal pattern of availability. Birds were more frequent early in the morning and their activity on flowers further declined, apparently following the pattern of nectar availability. The manner to which birds probed the flowers and, in consequence, their role on pollination were greatly determined by morphological traits and approaching behavior of birds. E. speciosa seemed best suited for pollination by long-billed hummingbirds but some short to medium-billed species may play some role on its pollination.
The family Compositae has ca. 25,000 species and is estimated to have diverged approximately 45 Ma. Within the family, the small subfamily Barnadesioideae (91 spp.) is the sister group of the rest of Compositae. Four of its nine genera have only one species; one of these, Fulcaldea, is restricted to northern Peru and Ecuador as is its sister group, Arnaldoa (3 spp.). A new species, Fulcaldea stuessyi, is described from the Chapada Diamantina of Bahia, Brazil, a remarkable 4000 km disjunction. The new species is clearly a member of Fulcaldea sharing a number of important characters with the type, F. laurifolia, including a single-flowered capitulum, "plumose" pappus, shrubby habit, and style with a unique swelling. It is distinguished from that species by its red corolla and pappus, greater number of series of phyllaries, and much greater length of the corolla, style, and pappus. The location of the new taxon may be the result of vicariance or long-distance dispersal; it is named in honor of Professor Tod Stuessy.
The once prevalent view that the evolution of extreme ecological
specialization is accompanied by a loss of potential for adapting to new
conditions, and thus is irreversible, has been challenged by several
recent examples,,. However, we know of no modern phylogenetic studies
showing reversal in pollination relationships from extreme
specialization to generalization, although such reversals are
theoretically expected,. Here we present molecular phylogenetic evidence
for an evolutionary shift in Dalechampia (Euphorbiaceae) vines from a
highly specialized relationship (pollination by one or a few animal
species,) with resin-collecting bees to generalized pollination by a
variety of pollen-feeding insects. This shift was associated with
dispersal from Africa to Madagascar, where the specific resin-collecting
pollinators are absent. These results show that plants dispersing beyond
the range of their specific pollinators may succeed by evolving more
generalized pollination systems.
Floral evolution has often been associated with differences in pollina-tion syndromes. Recently, this conceptual structure has been criticized on the grounds that flowers attract a broader spectrum of visitors than one might expect based on their syndromes and that flowers often diverge without excluding one type of pollinator in favor of another. Despite these criticisms, we show that pollination syndromes provide great utility in understanding the mechanisms of floral diversification. Our conclusions are based on the importance of organizing pollinators into functional groups according to presumed similarities in the selection pressures they exert. Furthermore, functional groups vary widely in their effectiveness as pollinators for particular plant species. Thus, although a plant may be visited by several functional groups, the relative se-lective pressures they exert will likely be very different. We discuss various methods of documenting selection on floral traits. Our review of the literature indicates over-whelming evidence that functional groups exert different selection pressures on floral traits. We also discuss the gaps in our knowledge of the mechanisms that underlie the evolution of pollination syndromes. In particular, we need more information about the relative importance of specific traits in pollination shifts, about what selective factors favor shifts between functional groups, about whether selection acts on traits inde-pendently or in combination, and about the role of history in pollination-syndrome evolution.
The perfume syndrome and pollination by fragrance-collecting euglossine bees in the neotropic solanaceous genusCyphomandra was confirmed by field observations. In SE Brazil,C. sciadostylis was visited byEufriesea violaceae, andC. diploconos byEuglossa mandibularis; C. hartwegii was pollinated byEulaema meriana in Costa Rica. The primary attractant, fragrant droplets that ooze from the dorsally bulged connectives, is mopped up by the males with the forebasitarsi. Thereby, the poricidal thecae are inadvertently pushed causing the dry pollen to dust the bee''s sternum. The number and direction of the pollen jets are related to pollinator size and stigma structure. The flowers are homogamous, selfsterile, and last three days. The androecium is optically non-contrasting or has cryptic colour. Flowers ofC. sciadostylis andC. diploconos undergo a colour change and an almost three-fold increase in corolla size when scent production and visits cease. The dorsal papillar epidermis of the connective is underlain by a glandular parenchyma typical of osmophores. GC techniques revealed germacrene D as the main component in the mentholic scent ofC. sciadostylis, ipsdienol, heneicosane, and tricosane as dominant in the nutmeg-like scent ofC. diploconos, and benzyl acetate and benzyl alcohol in the sweet fragrance ofC. hartwegii. In all cases, these were accompanied by numerous minor components of heterogeneous chemical nature.—Pollen release by means of a peculiar pneumatic bellows mechanism appears as a necessary and probably ubiquitous feature ofCyphomandra. Even a slight pressure exerted upon the thin, elastic thecal walls blows pollen jets through the pores. Unusual anatomic changes accompany anther maturation. Initially voluminous parenchymatic locular intumescences (placentoids) contract completely during meiosis, then expand once more when the pollen is ripe, pushing the grains against the locular wall, and contract a second time, allowing air to enter the thecae.—Cyphomandra pinetorum was found to be exceptional in exhibiting a pollen flower syndrome, and not cryptical but optically contrasting yellow anthers, as known forSolanum.
Nectar and floral odor are frequently associated with the presence and maintenance of specialized pollination systems in Orchidaceae.
We studied flowers of four Acianthera species, a genus of myophilous orchids belonging to the largest fly-pollinated orchid group Pleurothallidinae, in order to
characterize the secretory structures related to their pollination mechanism. Flowers at anthesis were sampled to detect volatile
compounds and nectar; samples were fixed for light microscopy and scanning and transmission electron microscopy. The labellum
presents epidermal cells and the first mesophyll layer involved with secretory processes. Cellular characteristics of these
regions associated with the occurrence of sugars allowed us to recognize them as nectaries. Some portions of the sepals also
shown to be involved with secretory processes and the presence of nitrogenated volatile compounds characterize them as osmophores.
The production of nectar in these species makes the occurrence of sapromyophily questionable, even though these flowers present
characteristics of this floral syndrome. The presence of osmophores on the sepals reinforces that this localization is common
among the Pleurothallidinae, whilst they occur in a different region (labelum) in the other major fly-pollinated orchid group
(Bulbophyllum).
Keywords
Acianthera
-Cell ultrastructure-Myophily-Nectaries-Orchidaceae-Osmophores
The subfamily Mutisioideae (74 genera, ca. 865 species), which comprises three tribes, Mutisieae (43 genera, ca. 500 species), Nassauvieae (25 genera, ca. 315 species), and Stifftieae (six genera, 48 species), is analyzed at the generic level. A total of 87 genera traditionally related to Mutisioideae were studied. The genera of Mutisioideae are described and illustrated, and keys to tribes and genera are given. Corollas, anthers, styles, and pollen, are analyzed and discussed. The styles (smooth, rugulose to papillose, papillae short and rounded) constitute the main characters for delimiting the subfamily. The presence and distribution of the style papillae support the recognition of three tribes, although other characters as corolla shape contribute to their definition. The pollen of Nassauvieae can be clearly differentiated from the pollen of Mutisieae and Stifftieae. The morphology supports the exclusion of Brachylaena, Cloiselia, Dicoma, Duseniella, Erythrocephalum, Gladiopappus, Hesperomannia, Macledium, Moquinia, Pasaccardoa, Pleiotaxis, Tarchonanthus, and Warionia but not the exclusion of other taxa, for example, Hecastocleis, the Gochnatia complex, or the Ainsliaea group members.
We elucidated scent components, daily emission patterns, and the localization of floral scent release of Mirabilis jalapa. Volatiles emitted by the whole plant as well as by detached flowers were investigated using dynamic headspace analysis and gas chromatography/ mass spectrometry. Among several constituents including (Z)-3-hexenyl acetate, β-myrcene, (Z)-ocimene, and benzyl benzoate, the monoterpene (E)-β-ocimene was the major fragrance component. Fragrance release occurred in a time-dependent manner. The emission of volatiles, including (E)-β-ocimene, showed an evening-specific maximum (1700-2000 pm). The emission of (Z)-3-hexenyl acetate reached its maximum 3 h later. Histological (neutral red staining) and morphological studies (electron and light microscopy) of the flower surface and tissues of M. jalapa revealed differences in surface structures and tissue characteristics. The flower could be divided into four main sections, including the tube, the transition zone between tube and limb, a star-shaped center of the limb, and petaloid lobes of the limb. These petaloid lobes are the site of (E)-β-ocimene release. Stomata and trichomes found on the abaxial flower surface were not directly involved in fragrance release. Clear indications of osmophores involved in scent release could not be found. Thus, the results indicate that floral volatiles probably are released by diffuse emission in M. jalapa.
We studied gland morphology, anatomy and the chemical composition of the floral fragrance in the sweat bee-pollinated orchid Cyclopogon elatus. This is apparently the first such analysis for any Cyclopogon species, and one of very few studies in which both odour and osmophore are characterised in a nectar-rewarding orchid. Structures responsible for floral scent production were localised with neutral red staining and histochemical assays for lipids and starch. Their morphology and anatomy were studied with scanning electron microscopy and light microscopy thin sections, respectively. Fragrance samples were collected using SPME fibres and analysed with GC-MS. Anatomical evidence suggests that two parallel oval-shaped patches of unicellular trichomes on the abaxial surface of the labellum are osmophores. These are rich in stored lipids, while the parenchyma surrounding the vascular bundles contains starch. Only freshly opened flowers produced odours, while buds and withered flowers lacked scent. The chemical composition of the odour was dominated (>99.8%) by a single compound, trans-4,8-dimethyl-nona-1,3,7-triene (DMNT). Gland anatomy and position on the outside of the perianth are unusual for scent glands in general. The presence of DMNT, a nearly ubiquitous compound in herbivore-induced vegetative emissions and one of the major floral volatiles of Yucca, is not surprising in view of hypotheses on the evolutionary origin of flower scents, suggesting that wound volatiles are utilised as kairomonal attractants by florivores whose activities result in pollination.
CRYOSTAT MICROTOME SECTIONS OF BIRCH WOOD DEGRADED BY WHITE ROT FUNGI WERE EXAMINED BY LIGHT MICROSCOPY AFTER TREATMENT WITH TWO STAINS: astra-blue, which stains cellulose blue only in the absence of lignin, and safranin, which stains lignin regardless of whether cellulose is present. The method provided a simple and reliable screening procedure that distinguishes between fungi that cause decay by selectively removing lignin and those that degrade both cellulose and lignin simultaneously. Moreover, morphological characteristics specific to selective delignification were revealed.
A thorough morphological circumscription of the tribe Mutisieae (Asteraceae) was established in 1977 by Angel L. Cabrera (1908–1999), who made fundamental worldwide contributions to the taxonomy of the family Asteraceae. The advance of molecular phylogenetic studies resulted in portrayals of relationships that have impacted the classification of the whole family and particularly of the Mutisieae. The publication of the book Systematics, Evolution and Biogeography of the Compositae in 2009, with the collaboration of the main worldwide specialists in the family, represented another fundamental milestone in the classification of the tribe. Mutisieae, which was previously thought to be nested far up in the phylogenetic tree of the family, is now known to be a basal grade, becoming a focus of attention for synantherologists. Traditional Mutisieae, or Mutisieae sensu Cabrera, is now split into numerous new subfamilies, tribes and subtribes. As a result of these changes, genera within the tribe have been reduced from 89 to 48 through new synonymisations, transfers to other tribes, and partly offset by description of 23 new genera. The remaining genera of Mutisieae sensu Cabrera have been placed in tribes of different subfamilies. A synthesis of these changes is presented in tables, in an illustrated key, and in a synopsis of the subfamilies with keys to tribes within the subfamilies.
Species of the Neotropical orchid genus Stanhopea produce a fragrance comprising terpenoids and aromatics which attracts euglossine bee pollinators. The secretory tissue, called an osmophore, is located in the adaxial region of a sac formed near the proximal portion of the floral lip. This region is easily recognized in Stanhopea oculata and S. wardii because it is papillate. The osmophore in these two species includes all the cells of the papillae and those directly below, that grade into fundamental tissue. Osmophore cells are more densely cytoplasmic than cells in the adjacent tissue. Numerous amyloplasts and mitochondria are seen in these cells from the earliest bud stages we examined through anthesis. Smooth and rough endoplasmic reticulum are abundant, but dictyosomes are uncommon. Mitochondria of osmophore cells appear to be distributed with no apparent pattern during bud stages, although they tend to be aligned near the plasmalemma at anthesis. Osmophore cells are highly vacuolate after anthesis.
Floral morphology, stages in floral development and insect visitation in Z. aethiopica are reported. Floral development can be divided into five phases: pre-female, female, male, fruit development and fruit ripening. Plants are self-incompatible and separation of sexes is achieved by marked protogyny. Z. aethiopica is the only member of the genus in which the basal part of the spathe turns green during fruit maturation while the apical part withers away. This species is further unique in that the berries turn orange, soft and mucilaginous on ripening. Both Z. aethiopica and Z. odorata have staminodes present amongst the ovaries and a faint scent is evident. Several insects, especially beetles, were seen visiting the inflorescence. Observations on Z. aethiopica are compared with other members of the genus, notably Z. albomaculata subsp. albomaculata.
Abstract—
A revision of the genus Stomatanthes (Asteraceae, Eupatorieae) is presented. A cladistic analysis of 43 qualitative and eight quantitative morphological characters resulted in one tree that suggests a narrower delimitation of the genus relative to previous
circumscriptions. Stomatanthes thus comprises three species, one widespread in sub-Saharan Africa and the other two endemic to restricted areas in central Africa. A cluster analysis and a non-metric multidimensional scaling were also performed. Of the 25 quantitative traits originally
measured for the analysis, eight (blade length and width, involucre length, corolla length, corolla limb width, corolla tube width, thecae length, anther apical appendage length) provided clustering information and indicated the same groupings as the cladistic analysis. This revision also
includes full descriptions of species, photographs, illustrations, and distribution maps.
A backbone phylogeny that fully resolves all subfamily and deeper nodes of Asteraceae was constructed using 14 chloroplast DNA loci. The recently named genus Famatinanthus was found to be sister to the Mutisioideae-Asteroideae clade that represents more than 99% of Asteraceae and was found to have the two chloroplast inversions present in all Asteraceae except the nine genera of Barnadesioideae. A monotypic subfamily Famatinanthoideae and tribe Famatinantheae are named herein as new. Relationships among the basal lineages of the family were resolved with strong support in the Bayesian analysis as (Barnadesioideae (Famatinanthoideae (Mutisioideae (Stifftioideae (Wunderlichioideae-Asteroideae))))). Ancestral state reconstruction of ten morphological characters at the root node of the Asteraceae showed that the ancestral sunflower would have had a woody habit, alternate leaves, solitary capitulescences, epaleate receptacles, smooth styles, smooth to microechinate pollen surface sculpturing, white to yellow corollas, and insect-mediated pollination. Herbaceous habit, echinate pollen surface, pubescent styles, and cymose capitulescences were reconstructed for backbone nodes of the phylogeny corresponding to clades that evolved shortly after Asteraceae dispersed out of South America. No support was found for discoid capitula, multiseriate involucres or bird pollination as the ancestral character condition for any node. Using this more resolved phylogenetic tree, the recently described Raiguenrayun cura + Mutisiapollis telleriae fossil should be associated to a more derived node than previously suggested when time calibrating phylogenies of Asteraceae.
Onoseris (Asteraceae, Mutisieae) is a genus of 31 species distributed from Mexico to Argentina through the Andes with its center of diversity in Peru. A phylogenetic analysis based on a detailed morphological study is provided. Urmenetea is used as the outgroup. Three most parsimonious cladograms are obtained based on the complete data set using Paup* 4.0b8. Two monophyletic groups are recognized: 1. Species with petiolate leaves, palmately veined blades with hastate base, and few-headed capitulescences, rarely thyrsoid capitulescences (O. acerifolia, O. alata, O. brasiliensis, O. cabrerae, O. castelnaeana, O. costaricensis, O. donnell-smithii, O. drakeana, O. fraterna, O. hastata, O. macbridei, O. onoseroides, O. peruviana, O. purpurea, O. sagittata, O. silvatica, and O. speciosa). 2. Species with sessile or subsessile leaves, elliptic and pinnately veined blades with attenuate base, and solitary capitula (O. albicans, O. amplexicaulis, O. annua, O. chrysactinioides, O. cumingii, O. gnaphalioides, O. humboldtiana, O. hyssopifiolia, O. linearifolia, O. lopezii, O. minima, O. odorata, O. salicifolia, and O. weberbaueri). These monophyletic groups are recognized as subgenera Onoseris and Hipposeris respectively. Onoseris salicifolia is chosen as the lectotype of Onoseris subg. Hipposeris. Corolla polymorphism within Onoseris shows that corolla morphology alone cannot be used to distinguish between subtribes Mutisiinae and Gochnatiinae. Biogeographically, Onoseris has a continuous distribution from the Southern Andes to Northern Andes and Central America, but no individual species is distributed on both sides of the Huancabamba Zone. A group of species in subgenus Onoseris distributed in Central America and Brazil are regarded as phylogenetically derived (e.g., O. brasiliensis, O. costaricensis, O. onoseroides).
A previous molecular study showed that Chucoa ilicifolia, the type species of the genus
Chucoa, is within the genus Onoseris clade. A new genus, Paquirea Panero & S.E. Freire, is
proposed and described to accommodate the other species of Chucoa, C. lanceolata, as Paquirea
lanceolata (H. Beltrán & Ferreyra) Panero & S.E. Freire, comb. nov. The new genus differs from
Onoseris in having actinomorphic corollas with lobes of equivalent size and discoid capitula.
Paquirea shares with other Onoserideae a shrubby habit, solitary capitula, epaleate receptacles, fivelobed
corollas, anthers with long tails, style branches dorsally papillose with rounded apices, and
heteromorphic pappi in three series. Among the Onoserideae, Paquirea, because of its solitary
capitula and shrubby habit, is most similar to Plazia and Aphyllocladus. Paquirea can be
distinguished from these genera by its conspicuously leafy stems (vs. leaves soon deciduous in
Aphyllocladus), alternate leaves (vs. spirally-arranged leaves in Plazia), discoid capitula (vs. radiate
capitula in Plazia), cream-colored corollas (vs. lilac to purple corollas in Aphyllocladus and white to
pink in Plazia), and glabrous achenes (vs. long-pilose achenes in Aphyllocladus). A key and a
comparative table to the seven genera of Onoserideae are also provided.
Gradient odour emissions in the inflorescence of the Araceae Sauromatum guttatum aim to attract a wide range of insects into the floral chamber. The volatiles are emitted from the spadix appendix, as well as the club-shaped organs located directly above the female flowers. Volatile analysis of various regions of the appendix and the club-shaped organs led to the identification of 163 compounds emitted by the appendix top, 124 by the appendix bottom and 105 by the club-shaped organs. The dominant compounds in all investigated tissues were monoterpenes and sesquiterpenes that were accompanied by numerous aliphatic, aromatic, sulphur- and nitrogen-containing compounds of other biosynthetic origins. Within the appendix, levels of one monoterpene, β-citronellene, showed considerable variation; it constituted the major compound in the appendix top and gradually decreased in the lower regions, being undetectable in the base. The other prominent monoterpenes, α-pinene, β-pinene, limonene, α-phellandrene and β-phellandrene, showed no changes along the appendix. The club-shaped organs located at the base of the floral chamber also emitted volatiles, though of different composition: the monoterpenes α-terpinolene and linalool constituted major amounts, instead of β-pinene and β-citronellene. These qualitative differences and the absence of methanethiol in the club-shaped organs result in them having a pleasant flowery odour, in contrast to the foul-smelling appendix. The quantitative spatial variation of β-citronellene within the appendix and the existence of a second osmophore within the floral chamber, emitting a different scent, suggest that both phenomena might participate in creating an odour gradient for efficient pollinator attraction. Apart from β-citronellene, nearly all major components of the appendix have already been identified as specific attractants to a broad range of insects that have been observed to be lured to the odour-emitting inflorescence. Most likely, the club-shaped organ odour serves to induce the insects attracted by the appendix to move towards the floral chamber. A comparison of the relative emission rates demonstrated that performance of the club-shaped organs equals or even exceeds the appendix. In the club-shaped organ tissues, multivesicular bodies, originating from lipid droplets, are the most notable organelles before and during odour production. They fuse with the plasma membrane, releasing their content to the exterior of the cell. The exit route for the volatiles is an extensive intercellular channel system that extends to the surface of the club-shaped organs. Thus, chemical and ultrastructural analyses suggest, in contrast to previous studies, that the club-shaped organs function as an osmophore rather than a food source for insects.
The genus Lycoseris is revised to include eleven species of dioecious subshrubs with mostly scrambling branches. It is distributed from Guatemala to northwestern and western South America, reaching south to Bolivia and southern Brazil. Three new species are described, viz. L. colombiana, L. minor, and L. peruviana. One new combination is made, viz. L. trinervis ssp. altissima.
To improve our understanding of the floral biology, pollination, and systematics of the genus Narcissus, a comparative study was made of flower volatiles from nine species native to southern Spain using headspace collection and GC-MS analysis. The species fell into three fragrance types based on the identity of their major volatiles. In all but one species the fragrances consisted mainly of monoterpene isoprenoids mixed with benzenoids: in six species trans-ß-ocimene occurred in high proportions, in two others it was lacking; the last species had a fragrance dominated by fatty acid derivatives, mixed with terpenoids. Two of the species showed marked intraspecific variation in many of their volatiles. When the volatile data matrix of all species was subjected to cluster analyses and the resulting phenetic trees compared with currently recognized taxonomic groups, there was no congruence at the subgeneric level. However, there was considerable agreement at the sectional level, although in most sections we studied only a single species. This apparent agreement was stronger when the volatiles were analyzed according to shared biosynthetic pathways rather than treated individually, pointing to the higher value of using biosynthetic pathways for uncovering and confirming phenetic, and probable evolutionary, relationships among species. In terms of possible selective pressures from pollinators in shaping fragrance chemistry, available information on the pollination of our species suggested an association between fragrance and types of pollinators. Two pollinator-fragrance groups were apparent: (1) species pollinated by insects that include butterflies and moths displayed fragrances containing volatiles typical of moth-pollinated flowers, most particularly indole combined with high amounts of esters, and (2) species visited exclusively by insects other than butterflies and moths, especially by bees and flies, had fragrances lacking this combination of volatiles. Narcissus assoanus was unusual among our species in having both fragrance chemotypes. Future pollination studies of Narcissus in the field are needed to test the reliability and predictability of the proposed fragrance-pollinator associations.
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