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SEM of variation in stigma morphology. Fig. 6, Dyckia ragonesei (Varadarajan 1218). Type II stigma at postanthesis, displaying the loosened stigmatic lobes. Note dissected areas (DL) of stigma lobes with pollen (P). Fig. 7, Navia splendens (Varadarajan 1215). Type III stigma during anthesis with convolute blades (CB); Fig. 8, Pitcairnia nuda (SEL 81-1979). Type II stigma during anthesis. Spiral folding involves mostly the individual lobes. Tubular papillate outgrowths (TP). Fig. 9, Pitcairnia heterophylla (Varadarajan 1171). Type II stigma during anthesis with noticeable spiral folding of individual lobes and entire stigmatic apparatus. Bulbous papillae (BP) are confined to edges of stigma lobes.
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Scanning electron and light microscopy observations of wet-preserved flowers of Bromeliaceae subfamily Pitcaimioideae yield new information on the stigma, petal scales, and septal nectaries. Variations of the stigma types are evident among several genera. The gross structural features of the stigma do not indicate definite pollination trends, but t...
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... Despite progressive floral senescence in D. dissitiflora and changes in stigma morphology, it remains receptive for a relatively long time. Several authors have noted that in Bromeliaceae, the peak of receptivity period coincides with the moment at which the flower becomes functional (Lenzi & Paggi, 2020;Queiroz et al., 2016;Souza et al., 2020;Varadarajan & Brown, 1988;Vosgueritchian & Buzato, 2006). The prolonged stigma activity and pollen viability observed in D. dissitiflora ensured its reproductive success, as those factors are crucial and directly affect mechanisms of reproduction. ...
The genus Dyckia (Bromeliaceae) is endemic to South America, and its species show important ecological roles in xeric environments. The flowering phenology as well as floral and reproductive biology were monitored monthly in Dyckia dissitiflora at two sites (Bela Vista:11º42'03.4"S 39º05'21.7"W and Barra do Vento:11º37'58.1"S 39º03'33.7"W) in the municipality of Serrinha, Bahia, Brazil. Flowering occurs in the early austral summer with a peculiar time of beginning of anthesis (10:00–11:00), offering resources 18 h after the first petal movements. Pollen viability was 98%, with a high production of pollen grains. Stigma receptivity is continuous from flower opening to senescence, and nectar production initiates at 04:00 and extends until 18:00. The species is self-compatible and autogamous, but not agamospermic. Pollen tubes developed and reached the micropyle within 24 h in all of the reproductive tests. The hummingbird Chlorostilbon lucidus was the only floral visitor and pollinator (frequency=0.82 ± 0.02). Fruiting occurs 3 days after anthesis, and the seeds are wind-dispersed. Self-compatibility and autogamy are essential strategies for the reproductive success of D. dissitiflora in light of the low number and visit frequency of its pollinators, and it is favored by slow floral movements and the position of the stigmas in relation to stamens.
... In Bromeliaceae, few works have evaluated the stigmatic surfaces and margins through detailed morphological and anatomical studies (e. g., Brown and Gilmartin, 1984;Varadarajan and Brown, 1988;Souza et al., 2020). Such studies have elucidated the morphological characteristics of Bromeliaceae stigmas and, as a result, increased taxonomic and phylogenic understanding of the family by the diversification of its stigmatic margins (Brown and Gilmartin, 1984), as well as reproductive biology (Heslop-Harrison, 2000). ...
... Moreover, as analyzed here, species of Brocchinia, Deuterocohnia, Fosterella and Pitcairnia lack epidermal appendages on stigmatic margins. This characteristic, when considered together with other features, such as reduction of stigmatic surfaces, favors pollination by insects, according to Proctor and Yeo (1972), Gardner (1986), and Varadarajan and Brown (1988). In addition to insect pollination, it is well know that most species of Bromeliaceae are pollinated by hummingbirds. ...
... Few studies in the literature have taken an evolutionary approach to stigmatic margins. Nonetheless, Varadarajan and Brown (1988) have commented on the relationship between pollinators and variations in the degree of stigmatic lobe compaction, the presence of trichomes on stigmas and petal scales, as well as septal nectaries. Mosti et al. (2013) have also suggested a relationship between ultrastructure and the secretion produced by septal nectaries with pollinators for Tillandsia species. ...
Bromeliaceae is one of the most diverse families in terms of morphology, especially its floral structure and stigmatic variability. Nineteen different stigmatic types are observed in the family, the margins of which differ in shape and presence or absence of epidermal appendages. Although many studies have classified stigma types, those that report on stigmatic margins are rare. Therefore, in this work, we aimed to study in detail the morphology of stigmatic margins in Bromeliaceae, including micromorphology and histochemistry, characterizing the secretions produced. To accomplish this, we used both optical and electron microscopy. Stigmatic margins of the twenty-two species studied were described as crenate, laciniate, lobate, undulate, and entire. We also observed unicellular, bicellular and multicellular secretory trichomes, branched or unbranched, with two to five arms. Stigmatic secretions, such as mucilage, total lipids, starch, polysaccharide, alkaloid and essential oil, were found. By addressing the diversity of stigmatic margins, we have added to the systematics of Bromeliaceae, including the morphology and histochemistry of epidermal appendages.
... The key-importance of stigma morphology in generic delimitations and the recognition of monophyletic lineages was widely explored by Barfuss et al. (2016) and Leme et al. (2017b), but the existence of several intermediate structures and subtypes makes the use of stigma morphology in Bromeliaceae taxonomy challenging, requiring constant reevaluation mainly when the optimal condition for study is achieved. The precise interpretation of stigma morphology requires caution and some experience because the structures change during development (Varadarajan & Brown 1988): compaction, lobe position, interwining, twisting and spiral folding and length, as well as lobe and margin curvature and presence of papillae (Brown & Gilmartin 1989). Thus, determination of stigma type should ideally be based on flowers immediately before anthesis (Brown & Gilmartin 1989), as was done here to identify the stigma type of Siqueiranthus as simple-erect with a tendency to simple-patent (figs. ...
The continuous refinement of the morphological, anatomical, and molecular studies on the genera of the “Cryptanthoid complex”, mainly considering the recently discovered outlier species, gave rise to new interpretations of species relationships.
It reinforced the monophyly of the groups, and allowed the recognition of the new monotypic genus Siqueiranthus based on a morphologically unique endemic species from northeastern Brazil on the brink of extinction, as well as generic status
for Krenakanthus and Orthocryptanthus previously conceived as subgenera of Orthophytum, with readjustments in the positioning of some species. An integrative approach with the combination of multiple traits and the critical assessment of
the diagnostic characters proved to be useful for the establishment of the new monophyletic genera. A new unusual species of Orthophytum is also described and illustrated, and its phylogenetic relationships are discussed.
... Ramírez (1991) was the first to describe and illustrate in detail the stigma of Hylaeaicum, recognizing the presence of conduplicate-spiral (in H. margaretae, H. mooreanum, and H. tarapotoense), convolute-blade (in H. eleutheropetalum and H. stoloniferum), and simple-erect (in H. levianum, H. myrmecophilum, and H. pendulum) types. However, precise interpretation of stigma morphology requires caution because the structures change during development (Varadarajan & Brown 1988) in compaction, lobe position, interwining, twisting, and spiral folding and length, as well as lobe and margin curvature and presence of papillae (Brown & Gilmartin 1989). According to Leme et al. (2017), optimal stigma lobe conservation is also fundamental for studying most stigma types because very soon after anthesis impregnation by pollen obscures and hinders recognition of stigma lobes, their shape, and ornamentation. ...
Generic status for the Amazonian Hylaeaicum is proposed within the Aechmea alliance, excluding it from the “Nidularioid complex” in general and from Neoregelia in particular. The monophyly of this new genus is supported by molecular phylogenetic analyses. The taxonomic circumscription of Hylaeaicum is based on the combination of geographical range and morphological characters, such as clonal growth, inflorescence structure, petal and corolla conformation, petal appendages, ovary, ovule, stigma, pollen, fruit, and seed, as well as seed anatomy, thoroughly documented and illustrated from field-collected specimens that flowered in cultivation in the Rio de Janeiro Botanical Garden, the Marie Selby Botanical Gardens, and in Refúgio dos Gravatás. The presence of seeds with long bicaudate appendages on both chalazal and micropylar ends is reported for the first time in Bromelioideae and considered an important character to distinguish Hylaeaicum from the related genera in the Aechmea alliance. In order to support the morphological distinctness of Hylaeaicum, the most varied and complete documentation of stigmata, fruits, and seeds of Bromelioideae is also presented for the first time, covering 24 genera and 17 subgenera. Fourteen new combinations, including 12 species and two varieties, are proposed.
... De acordo com Harms (1930), os apêndices ajudam a evitar a perda de néctar. Segundo Varadarajan & Brown (1988), os apêndices são vestígios e parecem não funcionais em alguns táxons de Pitcaimioideae e, em outras espécies de Pitcairnia funcionam como "escamas nectaríferas", que auxiliam na retenção de néctar. Outras funções para os apêndices são possíveis como guias, condução (retenção ou liberação) e proteção contra a dessecação do néctar (Brown & Terry 1992). ...
RESUMO— (O género Canistrum E. Morren (Bromeliaceae) no Estado do Paraná). Este trabalho é uni estudo taxonómieo das espécies do género Canistvum no Estado do Paraná. Canistrum cyathiforme
(Vell.) Mez e C lindenii (Regel) Mez são as únicas espécies pertencentes ao género, encontradas na flora paranaense. C. lindenii está restrita a três variedades e quatro fOrmas: C. lindenii (Regel) Mez var. lindenii f. lindenii; C. lindenii var- viride (E. Morren) Reitz f. magnum Reitz; C. lint/enii vara roseum (E. Morren) L. B. Sm. f. humile Reitz e C. lindenii var. roseum f. pocerum Reitz. São apresentadas chaves de identi ficaçüo, descrições, ilustrações e distribuição geográfica dos táxons estudados
... In all these subfamilies, the petal appendages have relatively simple and consistent morphology and appear as two small, non-vascular, protuberances that flank the antipetalous filament. In contrast, members of Bromelioideae have variable and elaborate petal appendages (Varadarajan & Brown, 1988;Benzing, 2000). ...
... The number of stigmas in Bromeliaceae can be correlated with the reproduction strategies and type of pollinators (Varadarajan & Brown, 1988;Benzing, 2000;Souza et al., 2016). To our knowledge, our results are the first to suggest a connection between conduplicatespiral stigma and the infra-or interlocular septal nectaries. ...
Aechmea (Bromeliaceae) is a large genus with controversial systematics and distinct flower shapes and pollinators. We explored floral anatomy and development in two Aechmea spp. belonging to different subgenera to contribute useful information on reproductive biology and taxonomy. We examined floral buds using scanning electron and light microscopy to characterize the development of septal nectaries, petal appendages, ovules, stamens and carpels. In A. gamosepala, we confirmed that the petal appendages develop late, whereas in A. correia-araujoi they develop earlier during floral development. Petal appendage formation included positional changes, possibly affecting floral attributes and visitation by insects, rather than vertebrates. Nectar is released through three basal orifices distally on the ovary, and here we document the link between the nectary region, through discrete canals, upward to the conduplicate lobes of the wet stigma. Improved understanding of the floral development and morphology of Aechmea may help to explain the existence of polymorphic flowers in this genus and may have implications for studies on interactions with pollinators and systematics.
... Bromeliaceae is a widely distributed Neotropical family with about 3600 species in 75 genera (Gouda et al. 2019). These plants are characterised by forming rosettes and having inflorescences with showy bracts and flowers in many of the species (Varadarajan & Brown 1988, Benzing 2000. Of the 321 species of Bromeliaceae in Bolivia distributed from the Andean paramo to the tropical lowlands, there are 146 endemics (Krömer et al. 2014). ...
Hummingbirds and bromeliad species of the genus Puya occur exclusively in the Neotropics. Their interaction is important for the reproduction and genetic variability of these plants. To understand this relationship, it is important to study the phenology of Puya species, their floral characteristics, and their floral visitors. In this work, we studied the floral ecology of the Bolivian endemic Puya atra, which grows in the montane cloud forests of the Yungas. We made monthly visits to the study area for two years to record phenology data, to collect nectar samples, and to make direct observations of floral visitors (539 observation hours) during its three-months of flowering. In this period, P. atra produced 8.09 ± 1.59 μL of nectar per flower, which contains fructose and glucose. We confirmed that P. atra is visited by two species of longed-bill hummingbirds: Coeligena violifer and Pterophanes cyanopterus, being males of both species the main visitors. The morphology of both visitors allows contact with the reproductive parts of its flowers and the transfer of pollen, while the plant rewards hummingbirds with nectar. It seems that P. cyanopterus showed a tight synchronisation with the plant's phenology and visited more frequently with a greater abundance of flowers, showing a positive interaction with P. atra. However, it is necessary to continue with different studies on the breeding system and sugar production throughout the day of this Puya species as well as the behavioural response of these hummingbirds in its presence.
Resumen Los colibríes y especies de bromeliáceas del género Puya se distribuyen exclusivamente en el Neotrópico. Su interacción es importante para la reproducción y la variabilidad genética de dichas plantas. Para comprender esta relación, es importante estudiar la fenología de las especies de Puya, sus características y visitantes florales. En este estudio analizamos la ecología floral de la especie endémica boliviana Puya atra, que crece en el bosque nublado montano de los Yungas. Visitamos el área de estudio mensualmente durante dos años para registrar datos de fenología, colectar muestras de néctar y hacer observaciones directas de visitantes florales (539 horas de observación) durante tres meses de su floración. En este periodo, P. atra produjo 8.09± 1.59 μL de néctar por flor, el cual contenía fructuosa y glucosa. Confirmamos que P. atra es visitada por dos especies de colibríes de pico largo: Coeligena violifer y Pterophanes cyanopterus, siendo los machos los principales visitantes para ambas especies. La morfología de ambos visitantes permite el contacto con las partes reproductivas de las flores y la transferencia de polen, mientras que la planta ofrece a los colibríes néctar. Al parecer P. cyanopterus mostró una estrecha sincronización con la fenología de la planta y la visitó con mayor frecuencia cuando hay mayor abundancia de flores, mostrando una interacción positiva con P. atra. Sin embargo, es necesario continuar con diferentes estudios sobre su sistema de reproducción y la producción de azúcar a lo largo del día de esta especie de Puya, así como la respuesta comportamental de estos colibríes en su presencia.
... Bromeliaceae is a widely distributed Neotropical family with about 3600 species in 75 genera (Gouda et al. 2019). These plants are characterised by forming rosettes and having inflorescences with showy bracts and flowers in many of the species (Varadarajan & Brown 1988, Benzing 2000. Of the 321 species of Bromeliaceae in Bolivia distributed from the Andean paramo to the tropical lowlands, there are 146 endemics (Krömer et al. 2014). ...
Hummingbirds and bromeliad species of the genus Puya occur exclusively in the Neotropics. Their interaction is important for the reproduction and genetic variability of these plants. To understand this relationship, it is important to study the phenology of Puya species, their floral characteristics, and their floral visitors. In this work, we studied the floral ecology of the Bolivian endemic Puya atra, which grows in the montane cloud forests of the Yungas. We made monthly visits to the study area for two years to record phenology data, to collect nectar samples, and to make direct observations of floral visitors (539 observation hours) during its three-months of flowering. In this period, P. atra produced 8.09 ± 1.59 μL of nectar per flower, which contains fructose and glucose. We confirmed that P. atra is visited by two species of longed-bill hummingbirds: Coeligena violifer and Pterophanes cyanopterus, being males of both species the main visitors. The morphology of both visitors allows contact with the reproductive parts of its flowers and the transfer of pollen, while the plant rewards hummingbirds with nectar. It seems that P. cyanopterus showed a tight synchronisation with the plant's phenology and visited more frequently with a greater abundance of flowers, showing a positive interaction with P. atra. However, it is necessary to continue with different studies on the breeding system and sugar production throughout the day of this Puya species as well as the behavioural response of these hummingbirds in its presence.
... clade (seven switches), in Bromelia L. (two switches) and in Deuterocohnia Mez (one switch) (Aguilar-Rodríguez et al., 2019). Finally, in Puya Molina, bat pollination is reported for four species (Vogel, 1969;Varadarajan & Brown, 1988;Aguilar-Rodríguez et al., 2019), and generalist songbird pollination is reported for at least five species (Johow, 1898;Scogin & Freeman, 1984;González-Gómez et al., 2004;Hornung-Leoni, González-Gómez & Troncoso, 2013), whereas Givnish et al. (2014) reconstructed the genus as being purely hummingbirdpollinated based on eight out of 214 species. ...
At least half of the 3600 species of Bromeliaceae are pollinated by hummingbirds. There is little doubt that the four to 12 evolutionary shifts towards and c. 32 shifts away from hummingbird pollination opened new evolutionary spaces for bromeliad diversification, and that hummingbird pollination has led to increased bromeliad diversification rates. However, the mechanisms leading to these increased rates remain unclear. We here propose that there are four main types of mechanisms that may increase diversification rates of hummingbird-pollinated bromeliad clades: (1) bromeliad speciation through adaptation to different hummingbird species; (2) increased allopatric speciation in hummingbird-pollinated clades due to lower pollen transfer efficiency compared with other pollinators; (3) differential speciation rates in hummingbird-pollinated clades dependent on of flowering phenology and hummingbird behaviour; and (4) higher speciation rates of bromeliads in montane environments (where hummingbird pollination predominates) due to topographic population fragmentation. To date, none of these hypotheses has been appropriately tested, partly due to a lack of data, but also because research so far has focused on documenting the pattern of increased diversification in hummingbird-pollinated clades, implicitly assuming that this pattern supports an underlying mechanism while ignoring the fact that several competing mechanisms may be considered. The aim of the present review is to increase awareness of these mechanisms and to trigger research aimed at specifically testing them. We conclude that much additional research on the roles of hummingbird behaviour and gene flow between bromeliad species is needed to elucidate their contribution to the evolution of diversity in bromeliads and other plant families.
... clade (seven switches), in Bromelia L. (two switches) and in Deuterocohnia Mez (one switch) (Aguilar-Rodríguez et al., 2019). Finally, in Puya Molina, bat pollination is reported for four species (Vogel, 1969;Varadarajan & Brown, 1988;Aguilar-Rodríguez et al., 2019), and generalist songbird pollination is reported for at least five species (Johow, 1898;Scogin & Freeman, 1984;González-Gómez et al., 2004;Hornung-Leoni, González-Gómez & Troncoso, 2013), whereas Givnish et al. (2014) reconstructed the genus as being purely hummingbirdpollinated based on eight out of 214 species. ...
At least half of the 3600 species of Bromeliaceae are pollinated by hummingbirds. There is little doubt that the four to 12 evolutionary shifts towards and c. 32 shifts away from hummingbird pollination opened new evolutionary spaces for bromeliad diversification, and that hummingbird pollination has led to increased bromeliad diversification rates. However, the mechanisms leading to these increased rates remain unclear. We here propose that there are four main types of mechanisms that may increase diversification rates of hummingbird-pollinated bromeliad clades: (1) bromeliad speciation through adaptation to different hummingbird species; (2) increased allopatric speciation in hummingbird-pollinated clades due to lower pollen transfer efficiency compared with other pollinators; (3) differential speciation rates in hummingbird-pollinated clades dependent on of flowering phenology and hummingbird behaviour; and (4) higher speciation rates of bromeliads in montane environments (where hummingbird pollination predominates) due to topographic population fragmentation. To date, none of these hypotheses has been appropriately tested, partly due to a lack of data, but also because research so far has focused on documenting the pattern of increased diversification in hummingbird-pollinated clades, implicitly assuming that this pattern supports an underlying mechanism while ignoring the fact that several competing mechanisms may be considered. The aim of the present review is to increase awareness of these mechanisms and to trigger research aimed at specifically testing them. We conclude that much additional research on the roles of hummingbird behaviour and gene flow between bromeliad species is needed to elucidate their contribution to the evolution of diversity in bromeliads and other plant families.
