Corolla Aestivation Research Articles

Seed morphology of Hamelieae with emphasis on the Deppea complex (Cinchonoideae, Rubiaceae)

Background and aims – The neotropical tribe Hamelieae currently includes 16 genera mainly characterized by raphides, ebracteolate inflorescences, and 4-merous flowers with contorted corolla aestivation. Within this tribe, the circumscription of Deppea has been particularly controversial, as depending on the authors, several morphologically closely related genera are either treated as synonyms or accepted as such. This generic group, hereafter referred to as the Deppea complex, consists of up to 10 genera. Within Rubiaceae, seed morphology has proved to have taxonomic value for generic circumscriptions, however, it remained unexplored for Hamelieae and the Deppea complex.Material and methods – We present a detailed study of the seed morphology of 37 species representing 15 out of the 16 genera recognized within Hamelieae, including all putative genera of the Deppea complex. Using scanning electron and light microscopy, we investigate 16 quantitative and qualitative seed characters that could have taxonomic value.Key results – Our results show that the combination of some seed characters, such as shape and colour, dorsiventral compression, hilum position, and the periclinal microrelief, helps to distinguish some genera and most species, supporting or refuting the current taxonomic circumscription.Conclusion – We conclude that the seed morphology within Hamelieae has taxonomic value but should be combined with other characters to achieve unequivocal delineation of the genera.

A Taxonomic Treatment of Rogiera (Guettardeae, Rubiaceae)

Abstract—Rogiera (Guettardeae, Rubiaceae) is a Neotropical genus distributed from Mexico to northern South America that includes shrubs, treelets, or trees, which were previously treated in the taxonomically controversial and confused Rondeletia complex. Rogiera can be recognized among other Rubiaceae by the combination of multiflowered inflorescences, heterostylous flowers, quincuncial corolla aestivation, a hairy ring at the corolla mouth, and capsular fruits with loculicidal dehiscence. Despite the recent taxonomic circumscription of Rogiera there is not a comprehensive taxonomic treatment to it. Moreover, regional floristic treatments disagree on the species circumscriptions, with discrepancies in the number of species of Rogiera from 11 to 20. Based on molecular and morphological evidence studied on field and herbarium specimens, we present a taxonomic revision of Rogiera. We recognize ten species; Mexico is the center of diversity with nine species, four of them endemic. An identification key, descriptions, distribution maps, nomenclatural history, phenological data, and illustrations of all the species in the genus are provided for the first time. Several names required lecto- or epitypifications designated here.

<p><strong><em>Perakanthus longipetalus </em></strong><strong>(Rubiaceae), a new combination, and the first record of the genus outside Peninsular Malaysia</strong></p>

Canthium longipetalum Y.H.Tan & S.S.Zhou in Yang et al. (2019: 197) is a species of Rubiaceae recently described from northern Myanmar. This species was identified as belonging to the Vanguerieae tribe, and was placed provisionally in the genus Canthium Lamarck (1783: 602) based on morphological characters including the presence of axillary inflorescences, valvate corolla aestivation, two-locular ovaries, and a two-lobed stigma (Yang et al. 2019). However, the suite of characters cited by the authors to support the placement of their species in Canthium define an overly broad and now-superseded concept of the genus.

It is not a disaster: molecular and morphologically based phylogenetic analysis of Rondeletieae and the Rondeletia complex (Cinchonoideae, Rubiaceae)

The circumscription of Rondeletieae has changed considerably over time. Historically, 85 genera have been included, characterized by small trees, imbricate corolla aestivation and capsules. Molecular studies led to a narrower circumscription and stressed out that Rondeletieae is mainly an Antillean clade. As historically circumscribed, Rondeletieae is both polyphyletic (involving several tribes, including Condamineae, Sipaneeae, etc.) and paraphyletic with respect to Guettardeae. Uncertainties persist on the tribal circumscription, and its generic limits and relationships. We report results of phylogenetic analyses under parsimony, maximum likelihood and Bayesian analyses including 179 taxa, using concatenated datasets of three chloroplast DNA regions (petD, trnL–F and trnK–matK), their DNA microstructural characters as well as morphology. Our objectives are to: test the monophyly of Rondeletieae and evaluate phylogenetic relationships, evaluate potential characters for tribal and generic delimitation and propose a circumscription for Rondeletieae according to phylogenetic hypothesis using morphological characters. The tribes Guettardeae and Rondeletieae are strongly supported as sister: quincuncial aestivation and spathulate corolla lobes are proposed as a unique combination of characters supporting this relationship. We did not find synapomorphies for each tribe, but there is a set of character combinations that allows distinguishing both tribes that includes the corolla and pollen ornamentation as well as fruit and seed morphology. After evaluating other genera not included in the phylogenies, our proposal is that Rondeletieae contains approximately 120 species in 20 neotropical genera: Acrosynanthus, Acunaeanthus, Blepharidium, Donnellyanthus, Mazaea, Phyllomelia, Rachicallis, Roigella, Rondeletia, Rovaeanthus, Suberanthus, Tainus, plus one tentatively included and recently described (Jamaicanthus).

Phylogenetic relationships among species of Barleria (Acanthaceae, Lamiales): Molecular data reveal complex patterns of morphological evolution and support a revised classification

Barleria is a genus of ~300 species of herbs and shrubs in Africa and Asia, with highest diversity in tropical East Africa and southern Africa. The genus is part of Barlerieae (Acanthaceae), a lineage that is distinguished from other Acanthaceae by quincuncial corolla aestivation. Unequivocal synapomorphies have yet to be identified for Barleria. However, among Barlerieae, species of Barleria can be recognized by the combination of 4‐partite calyces with the anterior and posterior lobes usually larger than the two lateral lobes, pollen with a coarsely reticulate (honeycomb) exine and the corolla limb variously subactinomorphic to strongly zygomorphic but never markedly bilabiate with a hooded upper lip. All Barleria that we have observed also have filaments that twist through 180° and cross just distal to the synstapetal zone. Barleria species have previously been classified into two subgenera and seven sections based on differences in leaf axil spine systems; configuration of the corolla, androecium and stigma; and morphology of the capsule and seed. We tested the subgeneric classification of Barleria by sampling 53 Barleria species and 9 outgroup species for three plastid intergenic spacers (trnS‐G, ndhF‐rpl32‐trnL(UAG)) and the nuclear region nrITS. We found a monophyletic Barleria and support for the two currently recognized subgenera; four of seven currently recognized sections are monophyletic but one of these four, sect. Fissimura, is nested within other sections. Species of sect. Fissimura unexpectedly resolved in subg. Barleria with strong support, although previous classifications placed the section in subg. Prionitis. We propose recognizing two subgenera (i.e., Barleria, Prionitis), the latter comprising three sections (i.e., Prionitis, Somalia, Stellatohirta). Barleria encompasses remarkable morphological diversity; we used an ultrametric tree to examine the evolution of nine morphological traits used to define infrageneric taxa in previous classifications. All characters evolved homoplasiously, but a few states (e.g., woody capsule septa) are supported as synapomorphies, and combinations of characters can be used to delimit subgenera. Members of subg. Barleria have 4‐seeded capsules that lack a prominent beak, with a transition to 2‐seeded capsules in the clade that corresponds to sect. Fissimura. In contrast, members of subg. Prionitis have 2‐seeded capsules (reversed to 4‐seeded in most members of one clade of sect. Somalia) that generally have a prominent beak. Additionally, we surveyed pollen morphology for 15 species sampled from across the classification. Pollen is consistently tricolporate with a coarse honeycomb exine. We provide an infrageneric classification and key to infrageneric taxa of Barleria.

Bertilanthus scanicus, a New Asterid Flower from the Late Cretaceous (Late Santonian–Early Campanian) of Scania, Sweden

A new genus and species of fossil flowers, Bertilanthus scanicus, is described from the Late Cretaceous of southern Sweden. The flowers of B. scanicus are actinomorphic and bisexual with an inferior ovary. Perianth and androecium are pentamerous. The sepals are small and free, and calyx aestivation is apert; petals are larger, and aestivation of corolla is imbricate. The androecium consists of a single whorl of stamens opposite the petals. The anthers are dithecate, tetrasporangiate, sagittate, and dorsifixed. Pollen observed in the flower is minute and oblate to spheroidal with three colpi and a tectate-punctate pollen wall. The gynoecium is formed from two carpels, and there are two free and stout styles. The epidermal cells of the styles are palisade shaped and form a distinct radiating pattern. The ovary is unilocular with numerous anatropous ovules borne on two intruding parietal placentae. There is a distinct five-parted nectary disk inserted between perianth and styles. The fruit was probably dry and capsular with apical dehiscence between the styles. Bertilanthus scanicus shares the presence of the unusual radiating palisade cells of the styles with Silvianthemum suecicum, another taxon described from the Åsen locality based on fossil flowers. Other critical features shared between Bertilanthus and Silvianthemum, including minute, tectate-punctate pollen, papillate-spiny extension of the palisade cells, free and stout styles, unilocular ovary, parietal placentation with placentae extending almost to the center of the ovary, and numerous anatropous ovules with reticulate surface, indicate that the two genera are closely related and also link these fossils to extant Quintinia, currently placed in the Paracryphiaceae (Paracryphiales) in the asterid clade.

Comparative Floral Development and Structure of the Black Mangrove GenusAvicenniaL. and Related Taxa in the Acanthaceae

Phylogenetic relationships of Avicennia have been difficult to trace because of the presence of convergent characters related to the mangrove environment. Recent molecular data suggest a close relationship to Thunbergioideae, a subfamily within Acanthaceae (Lamiales), but morphological support for the new findings has been equivocal. Floral structure and development are comparatively studied here in three species of Avicennia, with special attention given to the ovary and the ovules, which are also studied in Thunbergioideae. The suggested sister group relationship of Avicennia and Thunbergioideae is supported by three synapomorphies: (1) collateral ovule arrangement, (2) vertical orientation of ovule curvature, and (3) an exposed nucellus that is contiguous with the ovary wall, at least during early stages of ovule development. We interpret the latter character as a neotenic feature that is retained in the anthetic ovules of Avicennia. We confirm that the apparently tetramerous flowers of Avicennia have a basically pentamerous floral ground plan. Additional floral characters shared between Avicennia and Thunbergioideae include left contort corolla aestivation, thickened filament bases with glandular hairs, presence of pollen sac placentoids, and various aspects of fruit morphology and embryology. However, these features are either symplesiomorphic or are not known well enough to allow for unequivocal conclusion on character evolution in Acanthaceae.

Molecular Confirmation on the Phylogenetic Position of the Genus <i>Clemensiella</i> Schltr. in Marsdenieae (Apocynaceae - Asclepiadoideae)

The Philippine Marsdenieae (Apocynaceae-Asclepiadoideae) comprises a total of seven genera including the imperfectly known Clemensiella Schltr. Due to its unique morphology, the position of the small genus in the tribe Marsdenieae of Asclepiadoideae was previously in question. In this first molecular study of Clemensiella , the internal transcribed spacer (ITS, nrDNA) region of three isolates were newly generated and analyzed together with previous published sequences. The present aims to assess the phylogenetic positon, monophyly and closely-related genera of Clememsiella . The three Clemensiella isolates yielded a total of 630 to 642 base pairs (bp) and the average GC content ranged from 63.21% to 63.86%. Based on the strict consensus tree, the monophyly of Clemensiella is highly supported with BS = 100% and nested within the tribe Marsdenieae with BS = 61%. This study confirms the phylogenetic position of Clemensiella in Marsdenieae and its close relation to Dischidia and Hoya . Although the three Marsdenieae are distinct in their seed structures, they share common features in habit, inflorescence and corolla aestivation. KEYWORDS: Clemensiella ; ITS, Marsdenieae; Apocynaceae; Asclepiadoideae DOI: 10.3860/pjsb.v4i0.1564 P hilippine Journal of Systematic Biology Vol. IV (June 2010) 55-66

Diversity and evolution of floral structure among early diverging lineages in the Ericales.

This is a combination of review and original data on floral structure and diversity in the two earliest diverging lineages of the Ericales, i.e. the balsaminoids, comprising Balsaminaceae, Marcgraviaceae and Tetrameristaceae, and the polemonioids, comprising Fouquieriaceae and Polemoniaceae. Each clade is strongly supported in molecular studies, while structural synapomorphies have largely been lacking. For the balsaminoid families, we compare floral morphology, anatomy and histology among selected taxa and find that the entire clade is strongly supported by the shared presence of nectariferous tissue in the floral periphery, thread-like structures on anthers, truncate stigmas, secretion in the ovary, as well as mucilage cells, raphides and tannins in floral tissues. A possible sister group relationship between Balsaminaceae and Tetrameristaceae is supported by the shared presence of post-genital fusion of filaments and ovary and a star-shaped stylar canal. For polemonioids, we document unexpected diversity of floral features in Polemoniaceae, partly providing structural links to Fouquieriaceae. Features include cochlear and quincuncial corolla aestivation, connective protrusions, ventrifixed anthers and nectariferous tissue in the base of the ovary. In addition, we outline future directions for research on floral structure in the Ericales and briefly discuss the general importance of structural studies for our understanding of plant phylogeny and evolution.

Comparative Floral Structure and Systematics of Fouquieriaceae and Polemoniaceae (Ericales)

Floral morphology, anatomy, and histology are comparatively studied in Fouquieriaceae and Polemoniaceae, and previous studies are reviewed. In recent molecular phylogenetic analyses, the two families form a strongly supported clade within the asterid order Ericales, while they were generally placed far from each other in premolecular classifications. This study documents unexpectedly diverse floral features for Polemoniaceae, including various corolla aestivation patterns, different types of anther attachment and anther morphology, as well as two types of nectary structure. Prominent features shared by the two families include determinate‐terminal inflorescences, hyaline sepal margins, similar patterns of floral vasculature, late sympetalous corolla development, similar degrees of sympetaly, sterile connective protrusions, short thecal septa, endothecium‐like cells in the connective, trimery in the gynoecium, a stylar canal, parietal, and axile and placentation in the same ovary, similar patterns of ovule arrangement and ovule orientation, distally curved micropylar canals, mesophyll‐type nectaries with stomata, winged seeds, and seed coat epidermal cells with helical or annular wall thickenings. Several of these features represent potential synapomorphies for the clade with Fouquieriaceae and Polemoniaceae. In addition, potential synapomorphies are also identified for the individual families. While the results of this investigation further support the close relationship of Polemoniaceae and Fouquieriaceae, they also emphasize that it is necessary to abandon preconceptions about the “systematic importance” of certain characters that turn out to be more homoplasious than previously thought.

Taxonomic revision of the tribe Hymenodictyeae (Rubiaceae, Cinchonoideae)

The palaeotropical tribe Hymenodictyeae Razafim. & B. Bremer, belonging to the otherwise predominantly Neotropical subfamily Cinchonoideae s.s. (coffee family or Rubiaceae), is revised here. The tribe as presently circumscribed contains two genera, Hymenodictyon Wall. and Paracorynanthe Capuron ex J.-F. Leroy, and is distinct from the other Cinchonoideae tribes with capsular fruits in having stipules bearing large, deciduous colleters on the margins, valvate corolla aestivation, and lenticellate capsular fruits that contain elongate, bilaterally flattened, and accrescent placentae. We recognize 22 Hymenodictyon species, including four new species (H. antakaranensis sp. nov., H. epiphyticum sp. nov., H. madagascaricum sp. nov., and H. tsingy sp. nov.), and the two described species of Paracorynanthe. Hymenodictyon is distinguished from its sister genus, Paracorynanthe, by simple or compound spicate, racemose or thyrsoid inflorescences and corolla lobes without any appendages, rather than compound umbelliform inflorescences and corolla lobes prolonged by ciliate appendages. A full taxonomic treatment, keys, and distribution maps of all recognized Hymenodictyon and Paracorynanthe species are provided. Five lectotypes and one neotype are designated. Finally, six Hymenodictyon species are illustrated for the first time. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 152, 331–386.

A Revision of the Imbricate Group of Styrax Series Cyrta (Styracaceae) in Asia

Several taxonomic treatments of Styrax (Styracaceae) exist in regional floras of Asia, but the Asian species of the genus have not been comprehensively revised since 1907. To help rectify this, we conducted a taxonomic revision of the Asian species of Styrax series Cyrta with imbricate corolla aestivation. Our revision comprises 17 species with a combined distribution from Japan south to Sumatra and west to Nepal. The circumscriptions of the heretofore poorly defined species S. hookeri and S. serrulatus are clarified. Styrax agrestis var. curvirostratus is elevated to the species level, and lectotypes are selected for S. duclouxii, S. floribundus, S. hemsleyanus, S. hookeri, S. hookeri var. yunnanensis, S. hypoglaucus, S. japonicus, S. limprichtii, S. macranthus, S. obassia, S. perkinsiae, S. serrulatus var. latifolius, S. shiraianus, S. supaii, and S. wilsonii. Keys, descriptions, and distribution maps are provided for all species.

Ontogeny and morphology of the fertile flowers of Hydrangea and allied genera of tribe Hydrangeeae (Hydrangeaceae)

The monophyletic Hydrangeeae (Hydrangeaceae) consists of the cladeCardiandra +Deinanthe and its sister, the Hydrangea clade, which includes the paraphyleticHydrangea as well as Broussaisia, Decumaria, Dichroa, Pileostegia,Platycrater and Schizophragma. The plesiomorphic imbricate corolla aestivation and polystemony ofCardiandra and Deinanthe distinguish these two genera from most members of the Hydrangea clade.Deinanthe has postgenitally fused styles and cushion-like, dorsally positioned stigmas. The Hydrangea clade is notable because most species of Hydrangea share a floral morphology characterized by small size; tetramerous-pentamerous perianths; inconspicuous sepals; reflexed petals; diplostemony; stamens that are longer than the styles; completely inferior ovaries; separate styles; terminal, papillate stigmas; and dimerous-tetramerous gynoecia. This suite of states is termed the «Hydrangea floral syndrome» (HFS). Various members of the Hydrangea clade lack the HFS, including (1)Platycrater ; (2) Hydrangea anomala; (3) H. paniculata+H. heteromalla; (4) theSchizophragma clade (Schizophragma, Pileostegia and Decumaria); and (5) the macrophylla clade (H. macrophylla, H. scandens, H. hirta, Dichroa and Broussaisia). The meristic uniqueness of Decumaria reflects mutations observed in Arabidopsis (clavata) and Lycopersicon (fasciated) that cause organ number increases because of changes in meristem capital. The modification of early perianth development to form a prominent corolline torus at a point when sepals are diminutive is present in H. anomala andHydrangea section Cornidia and may be synapomorphic for them. Various transformations in the perianth, androecium, and gynoecium lie behind the floral diversity of Hydrangeeae. Some morphological transformations have been homoplastic, including shifts to polystemony, calyptrate corollas, and synstyly.

Ontogeny and morphology of the fertile flowers of Hydrangea and allied genera of tribe Hydrangeeae (Hydrangeaceae)

The monophyletic Hydrangeeae (Hydrangeaceae) consists of the cladeCardiandra +Deinanthe and its sister, the Hydrangea clade, which includes the paraphyleticHydrangea as well as Broussaisia, Decumaria, Dichroa, Pileostegia,Platycrater and Schizophragma. The plesiomorphic imbricate corolla aestivation and polystemony ofCardiandra and Deinanthe distinguish these two genera from most members of the Hydrangea clade.Deinanthe has postgenitally fused styles and cushion-like, dorsally positioned stigmas. The Hydrangea clade is notable because most species of Hydrangea share a floral morphology characterized by small size; tetramerous-pentamerous perianths; inconspicuous sepals; reflexed petals; diplostemony; stamens that are longer than the styles; completely inferior ovaries; separate styles; terminal, papillate stigmas; and dimerous-tetramerous gynoecia. This suite of states is termed the «Hydrangea floral syndrome» (HFS). Various members of the Hydrangea clade lack the HFS, including (1)Platycrater ; (2) Hydrangea anomala; (3) H. paniculata+H. heteromalla; (4) theSchizophragma clade (Schizophragma, Pileostegia and Decumaria); and (5) the macrophylla clade (H. macrophylla, H. scandens, H. hirta, Dichroa and Broussaisia). The meristic uniqueness of Decumaria reflects mutations observed in Arabidopsis (clavata) and Lycopersicon (fasciated) that cause organ number increases because of changes in meristem capital. The modification of early perianth development to form a prominent corolline torus at a point when sepals are diminutive is present in H. anomala andHydrangea section Cornidia and may be synapomorphic for them. Various transformations in the perianth, androecium, and gynoecium lie behind the floral diversity of Hydrangeeae. Some morphological transformations have been homoplastic, including shifts to polystemony, calyptrate corollas, and synstyly.

Phylogeny of Styrax Based on Morphological Characters, with Implications for Biogeography and Infrageneric Classification

It has been suggested that the characters on which the current infrageneric classification of the genus Styrax is based are not reliable. However, to date no alternative classification for the genus has been proposed. To address this problem, a phylogenetic analysis of Styrax was conducted using 34 morphological characters. Parsimony analysis suggested that none of the currently recognized subdivisions of Styrax are monophyletic except section Pamphilia. This section has traditionally been considered a distinct genus but the analysis placed it in a highly nested position, consistent with its recent transfer into Styrax. The biogeographical history of Styrax was inferred with Fitch parsimony analysis and dispersal-vicariance analysis. Results suggest that 1) the presence of Styrax in South America is the result of migration from southern North America; 2) back-migration from South America to North America has occurred in both montane and lowland tropical lineages; and 3) a migration from Eurasia to North America has occurred in four lineages. The phylogeny provides evidence for a single origin of morphological gynodioecy within the genus, a floral reduction series among the gynodioecious species, and a host shift by gall-forming aphids (tribe Cerataphidini) that parasitize Styrax. Included is a revised infrageneric classification based on the phylogeny with a key and descriptions, and the establishment of two new combinations (Styrax series Cyrta and Styrax series Benzoin). The genus Styrax L. consists of approximately 130 species of trees and shrubs distributed in eastern and southeastern Asia, the New World (mainly tropical), and the Mediterranean region (Fig. 1). Styrax is delimited from the other ten genera of Styracaceae by a stamen tube that is attached high on the petals, ovules with two integuments, and a thick, indurate seed coat. Traditionally the Styracaceae have been placed in the Ebenales (Cronquist 1988; Thorne 1992; Takhtajan 1997) but recent molecular data suggest affinities of at least part of the family (including Styrax) to the Ericales (Morton et al. 1996; Soltis et al. 1997). The most recent comprehensive taxonomic treatment of Styrax is that of Perkins (1907). In this treatment, Styrax was divided into section Foveolaria (Ruiz & Pav.) Perkins, comprising taxa with 3-5 ovules per ovary (two species, Greater Antilles and Peru) and section Styrax, with about 16-24 ovules per ovary (remaining species). Section Styrax was in turn divided into series Styrax (= Imbricatae [Giirke] Perkins; about 35 species) and series Valvatae (Giirke) Perkins (about 95 species). According to Perkins' (1907) infrageneric key, the species of series Styrax possess imbricate corolla aestivation, whereas the species of series Valvatae and section Foveolaria possess valvate corolla aestivation. Pamphilia Mart. ex A.DC., a strictly South American genus of six species, was maintained as a separate genus in Perkins (1907). However, it has recently been transferred to Styrax by Wallnofer (1997) as a section on the basis of its overall similarity to other species of Styrax from South America, particularly S. foveolaria Perkins and S. nui B.Walln. Section Pamphilia differs from the other members of Styrax by the possession of five (vs. ten or more) stamens and near-basal (vs. axile) placentation, and by the lack of placental obturators. Perkins' (1907) classification of Styrax has been used as a basis foI most regional treatments of Styracaceae (e.g., Hwang 1987; Svengsuksa and Vidal 1992; Hwang and Grimes 1996) despite suggestions in the literature that some of the infrageneric taxa may not be monophyletic (van Steenis 1932; Fritsch 1997). Perkins (1907) acknowledged a number of anomalous species within ser. Valvatae that were often polymorphic for aestivation type. This was affirmed by van Steenis (1932, 1949), who consequently did not recognize the two series in studies of the Malesian species of the genus. Wallnofer (1997) has documented infraspecific variation in the number of ovules per carpel in sections Pamphilia and Foveolaria. Although it is clear that corolla aestivation and ovule number are not likely to serve as a definitive basis for the infrageneric classification of Styrax, a comprehensive revision based on an alternative set of criteria has not been attempted. The objective of

Floral structure, development and diversity in Thunbergia (Acanthaceae)

Floral structure and development of 18 species of Thunbergia (Thunbergioideae s.l. , Acanthaceae) were studied comparatively. The flowers of Thunbergia are highly diverse and show a wide range of pollination syndromes. In general they are large and showy. Their pollination apparatus is highly elaborate, floral organs are often synorganized, and floral architecture is complex. In contrast to the high diversity of the anthetic flowers, their bauplan is uniform and their early development shows no major differences, i.e. in all species studied, the calyx arises as a ring primordium, the corolla is «late sympetalous», and petals and stamens are initiated more or less simultaneously. Some differences are found in further calyx development, where several developmental patterns are present. More significant differences arise only later during development and mainly concern the structures of the calyx, the anthers, the stigma, and corolla aestivation. In the anthetic flowers there are many special characters that are present in all or the majority of the species studied, e.g. the calyx is reduced, the corolla tube is subdivided into two compartments and the anthers lack an endothecium. The present results on development and morphology of the flowers of Thunbergia are compatible with an earlier subdivision of the genus into eight subgenera.

Floral structure, development and diversity in Thunbergia (Acanthaceae)

Abstract Floral structure and development of 18 species of Thunbergia (Thunbergioideae s.l. , Acanthaceae) were studied comparatively. The flowers of Thunbergia are highly diverse and show a wide range of pollination syndromes. In general they are large and showy. Their pollination apparatus is highly elaborate, floral organs are often synorganized, and floral architecture is complex. In contrast to the high diversity of the anthetic flowers, their bauplan is uniform and their early development shows no major differences, i.e. in all species studied, the calyx arises as a ring primordium, the corolla is «late sympetalous», and petals and stamens are initiated more or less simultaneously. Some differences are found in further calyx development, where several developmental patterns are present. More significant differences arise only later during development and mainly concern the structures of the calyx, the anthers, the stigma, and corolla aestivation. In the anthetic flowers there are many special characters that are present in all or the majority of the species studied, e.g. the calyx is reduced, the corolla tube is subdivided into two compartments and the anthers lack an endothecium. The present results on development and morphology of the flowers of Thunbergia are compatible with an earlier subdivision of the genus into eight subgenera.

New Species and Notes on the Natural History of Markea (Solanaceae) from Colombia and Ecuador

New Species and Notes on the Natural History of Markea (Solanaceae) from Colombia and Ecuador

Trends in Evolution of Floral Ontogeny in Cassia Sensu Stricto, Senna, and Chamaecrista (Leguminosae: Caesalpinioideae: Cassieae: Cassiinae); A Study in Convergence

Distinctions in floral ontogeny among three segregate genera (Cassia sensu stricto, Chamaecrista, and Senna) of Cassia L. support their separation. In all species studied, the order of floral organ initiation is: sepals, petals, antesepalous stamens plus carpel, and lastly antepetalous stamens. Sepal initiation is helical in all three genera, which however differ in whether the first sepal is initiated in median abaxial position (Senna), or abaxial and off-median (Cassia javanica), a rare character state among legumes. Order of petal initiation varies: helical in Senna vs. unidirectional in Cassia and Chamaecrista. Both stamen whorls are uniformly unidirectional. Intergeneric ontogenetic differences occur in phyllotaxy, inflorescence architecture, bracteole formation, overlap of initiation among organ whorls (calyx/corolla in Cassia; two stamen whorls in Chamaecrista), eccentric initiation on one side of a flower, anther attachment, anther pore structure, and precocious carpel initiation in Senna. The asymmetric corolla and androecium in Chamaecrista arise by precocious organ initiation on one side (left or right). The poricidal anther character can result from differing developmental pathways: lateral slits vs. sealing of lateral sutures; clasping hairs vs. sutural ridges; terminal pores (one or two) vs. none; and clamp layer formation internally that prevents lateral dehiscence. Genera differ in corolla aestivation patterns and in stigma type. Convergence is shown among the three genera, based on intergeneric dissimilarities in early floral ontogeny (floral position in the inflorescence, bracteole presence, position of the first sepal initiated, order of petal initiation, asymmetric initiation, overlap between whorls, anther morphology, and time of carpel initiation) resulting in similarities at anthesis (showy, mostly yellow salverform flowers, heteromorphic stamens, poricidal anther dehiscence, bee pollination, and chambered stigma).

Trends in evolution of floral ontogeny in Cassia sensu stricto, Senna, and Chamaecrista (Leguminosae: Caesalpinioideae: Cassieae: Cassiinae); a study in convergence

Distinctions in floral ontogeny among three segregate genera (Cassia sensu stricto, Chamaecrista, and Senna) of Cassia L. support their separation. In all species studied, the order of floral organ initiation is: sepals, petals, antesepalous stamens plus carpel, and lastly antepetalous stamens. Sepal initiation is helical in all three genera, which however differ in whether the first sepal is initiated in median abaxial position (Senna), or abaxial and off‐median (Cassia javanica), a rare character state among legumes. Order of petal initiation varies: helical in Senna vs. unidirectional in Cassia and Chamaecrista. Both stamen whorls are uniformly unidirectional. Intergeneric ontogenetic differences occur in phyllotaxy, inflorescence architecture, bracteole formation, overlap of initiation among organ whorls (calyx/corolla in Cassia; two stamen whorls in Chamaecrista), eccentric initiation on one side of a flower, anther attachment, anther pore structure, and precocious carpel initiation in Senna. The asymmetric corolla and androecium in Chamaecrista arise by precocious organ initiation on one side (left or right). The poricidal anther character can result from differing developmental pathways: lateral slits vs. sealing of lateral sutures; clasping hairs vs. sutural ridges; terminal pores (one or two) vs. none; and clamp layer formation internally that prevents lateral dehiscence. Genera differ in corolla aestivation patterns and in stigma type. Convergence is shown among the three genera, based on intergeneric dissimilarities in early floral ontogeny (floral position in the inflorescence, bracteole presence, position of the first sepal initiated, order of petal initiation, asymmetric initiation, overlap between whorls, anther morphology, and time of carpel initiation) resulting in similarities at anthesis (showy, mostly yellow salverform flowers, heteromorphic stamens, poricidal anther dehiscence, bee pollination, and chambered stigma).