Style Head Research Articles

Style head in Apocynaceae: a very complex secretory activity performed by one tissue.

Nuptial glands are very diverse and associated with different pollination mechanisms. The greater the specificity in the pollen transfer mechanism from anther to stigma, the greater the morphological elaboration of flowers and functional complexity of the nuptial glands. In Apocynaceae, pollination mechanisms reached an extreme specificity, a fact that was only possible due to an extreme morphological synorganization and a profusion of floral glands. Although these glands are of different types, the vast majority have secretory cells only in the epidermis. In general, these epidermal cells produce many different compounds at the same time, and previous studies have demonstrated that in the style head, the functional complexity of epidermis has become even greater. Four types of style head are found in the family, which have different degrees of functional complexity in relation to the secretion produced and pollen dispersal mechanism. The secretion is fluid in types I, II and III, and the pollen is dispersed and adhered to the pollinator by the secretion produced by the style head. In type IV, the secretion hardens and acquires a specific shape, moulded by the spatial constraints of the adjacent floral organs. This evolutionary alteration is accompanied by changes in the structure and arrangement of the secretory cells, as well as in pollen aggregation and position of stigma. Histochemical analysis has shown that the secretion is mixed and highly complex, especially in the style head type IV, where the secretion, called translator, is formed by a rigid central portion, which adheres to the pollinator, and two caudicles that attach to two pollinia. The translator has a distinct composition in its different parts. Further studies are needed to answer the new questions that have arisen from the discovery of this highly functional complexity of the secretory tissue.

What keeps the style under tension? Experimental tests to understand the biomechanics of the explosive style movement in Marantaceae.

Pollination in Marantaceae is mediated by an explosive style movement. Before release, style tension is held by the hooded staminode. When a pollinator touches the trigger appendage of the hooded staminode the latter deforms and the style rapidly curls upwards. This movement has been interpreted as a turgor movement by some authors, but recent studies clearly indicate that setup, hold and release of tension are purely mechanical processes. However, in view of the high diversity of hooded staminodes, the question arises what keeps the tension in species with very thin staminodes. To test the holding mechanisms, we conducted mechanical and physico-chemical release experiments in four species with robust and four species with thin hooded staminodes in their natural tropical environment. We found almost the same response of all species to mechanical treatments, but species-specific reactions to different physico-chemical conditions. This indicates that style release follows the same mechanical principles in all species, but that the sensitivity of the explosive movement depends on material properties like tissue thickness and turgescence. As to the holding mechanisms, we found different degrees of floral synorganization. The hood of the hooded staminode formerly interpreted as an important holding structure does not play a noteworthy role. Instead, the basal plate of the hooded staminode antagonises the pressure of the style head against the holding point of the hooded staminode in species with robust hooded staminodes and well-developed basal plates. In some species with a thin hooded staminode, the latter is closely attached to the style and most likely stabilises tension by adhesive forces. In another species, a morphologically analogous structure adopts the function of the basal plate. We conclude that the holding mechanism of the style tension diversified during the evolution of Marantaceae whereas the release mechanism itself has been conserved throughout the family.

Polystemma stevensii (Apocynaceae, Asclepiadoideae), a new species from Michoacán, Mexico

Polystemma stevensii, a new species from Michoacán, Mexico, is described and illustrated. It grows in tropical deciduous forest in the Balsas Depression at elevations from 350 to 750 m. Polystemma stevensii is similar to P. viridiflorum but differs by having a gynostegial corona with five lobes fused at the base to form a discontinuous flat ring (vs. not forming a discontinuous flat ring), an internal corona with two deltate lobes (vs. with one ligulate lobe), and globose style head (vs. flat style head). A distribution map of the new species and a key to determine the Polystemma species of Michoacán are provided. Following IUCN Red List guidelines, it is assigned a preliminary category of endangered, EN B1ab(i,ii,iii)+2ab(i,ii,iii). Polystemma now includes eight species, of which five are endemic to Mexico.

Taxonomic Considerations About the Anatomical Description of Gynecium Oxypetalum appendiculatum Mart. (Apocynaceae)

The flowers of Apocynaceae are considered as the most complex among the angiosperms, due to the occurrence of synorganization culminated in the origin of a new floral structure, the gynostege, formed by the union of androceu and gynecium, which guarantees an optimization in the reproduction process. The gynostegium is widespread in the genera of the subfamily Asclepiadoideae, being cited as an artifact of taxonomic significance in the group. Oxypetalum R.Br. It is the largest neotropical genus of Asclepiadoideae and is included in Clado MOOG, which presenting difficulties regarding the taxonomic positioning of its species. Few studies have investigated the floral anatomy of Oxypetalum and these did not address the taxonomic significance of the anatomy of the gynostegium in resolving the positioning of individuals in the group. This work seeks to investigate the anatomy of the gynecium and the gynecium of Oxypetalum appendiculatum in order to contribute to the group's taxonomy. With this, we seek to show key anatomical parameters for the easy identification of gaps in that group. Buds and flowers at pre-anthesis, anthesis, and post-anthesis were collected to analyze histologically. Material was fixed in karnovsky’s solution and gradually dehydrated in an ethanol series. Samples were infiltrated, and embedded in hydroxyethyl methacrylate. Circa 5 µm cross and longitudinal sections were cut using a rotary microtome, stained with Toluidine Blue O. All the slides were analyzed with optical and stereo microscopes and images were captured with a photomicroscope or a trinocular photo stereomicroscope. Gynoecium comprises two carpels fused at style and style head, with free ovaries. The five receptive parts of stigma are located on the gynostegium, more precisely behind the translators. At a higher level, the stigma begins to divide, appearing bifid, towards the apex. The gynoecium of Oxypetalum appendiculatum is an extremely complex structure due to the synorganization that occurred between the corona, the anthers and the gynecium itself. The result of this union is the gynostegium, which provides morphoanatomical characters that assist in delimiting this taxon and other species of this genus.

A fishing expedition to discover the pollinators of several subtropical Apocynaceae.

PremiseFlowers of the Apocynaceae (milkweed family) have complex structures and pollination mechanisms. Pollen removal and deposition in Angadenia, Pentalinon, and Echites are similar, with anthers releasing pollen onto the sterile style head. The mid‐style head excretes a glue that coats the mouthparts of vistors to aid in the transfer of pollen. Subsequent probes may deposit pollen on the receptive stigmatic surface on the lowest part of the style head, with fertilization resulting after pollination by compatible pollen.MethodsBy employing fishing line of different diameters, which reflected the diameters of the mouthparts of the different insect visitors, we determined the widths best able to remove and deposit pollen, thereby revealing which of the visitors could be effective pollinators, and which may be only nectar robbers.ResultsWe previously found that mouthpart (proboscis) width is correlated with pollen transfer effectiveness in Angadenia berteroi and confirmed this here in two other species, Pentalinon luteum and Echites umbellatus. Our data allowed the prediction of the most effective pollinators of these two other species.DiscussionThe simulation of flower visitor mouthparts using fishing line can provide useful data for evaluating the potential for effective pollen removal and deposition by different visitors.

Hoya amicabilis sp. nov. (Apocynaceae, Asclepiadoideae), from Java discovered on Facebook

A new species from Java, Hoya amicabilis S.Rahayu & Rodda is described and illustrated. It was first identified as a new species from pictures posted on social media in 2017. Hoya amicabilis is part of a small group of species that have an unusual shrubby habit, but it is the only one in that group with bright yellow campanulate flowers. Furthermore, Hoya amicabilis is a rather unusual species of Hoya since its staminal corona lobes are oblong, erect, while most species of Hoya have well‐developed generally spreading corona lobes, and its style head is umbonate, brightly coloured and extending above the anther appendages, while most species have a conical style head covered by anther appendages.

TRANSFORMATIONAL LEADERSHIP IN CHARACTER EDUCATION MANAGEMENT IN MADRASAH ALIYAH PROVINCE JAMBI

This study aims to describe the transformational leadership style in managing character education in MAN Jambi Province. This study used a qualitative approach with case study design. Research result; Transformational leadership factors have not been optimal in managing character education in MAN Jambi Province due to two factors; First, internal factors are; 1). Some heads and teachers do not fully understand the nature of character education 2). There is no guidebook that becomes guide 3). Students are not boarded up, so they are not full in character. Both external factors are; 1) Ministry of Religion Office has not yet instructed concretely about the management system of character education in Madrasas 2) Many parents of students still do not care about children's character education.
 Transformational leadership style Head of MAN 3 Jambi Province, can be seen from several indicators 1). Madrasah head who always brings change, 2). Communicate effectively, 3). Encourage subordinate performance, (d). Harmonize the work environment, (e). Improve ability continuously. The management model is planned, implemented, evaluated in an integrated manner with the management of the madrasah, its application through three main channels, namely (1) integrated through learning activities, (2) integrated through extracurricular activities, and (3) integrated through civilizing or habituation activities.
 Research conclusion; Transformational leadership of the head of Jambi Province madrasah madrasah has not been optimal in managing character education, but the content of planting character values goes naturally along with the learning system at the madrasa which is based on Islamic character.

Taxonomic implications of floral morphology in the subfamily Asclepiadoideae (Apocynaceae s.l.) in Korea

We examined the floral morphology of 15 taxa of five genera (Cynanchum, Marsdenia, Metaplexis, Tylophora, and Vincetoxicum) in Korean Asclepiadoideae using a stereoscopic and scanning electronic microscope to clarify and describe the floral characteristics. In this study, the corolla and corona types, the types of corona lobes, appendages on the corona lobes, and the apex shape of the style head are considered as diagnostic characteristics at the generic level. The genus Vincetoxicum, which is treated as a synonym of the genus Cynanchum in Korea, is distinguished from Cynanchum by the interstaminal part on the corona, fleshy and mainly triangular or ellipsoid corona lobes, and various corolla colors. In Cynanchum, various corona types have been observed, while Vincetoxicum have similar corona types among the taxa. In addition, the main floral characteristics at the species level were as follows: flowering time, inflorescence, corolla color, trichomes on the corolla surfaces, apex shape of the corona lobe, and trichomes on the ovary. This study presents the taxonomic importance of floral morphology by providing descriptions and diagnostic characteristics among the genera and species investigated.

Kindia (Pavetteae, Rubiaceae), a new cliff-dwelling genus with chemically profiled colleter exudate from Mt Gangan, Republic of Guinea.

A new genus Kindia (Pavetteae, Rubiaceae) is described with a single species, Kindia gangan, based on collections made in 2016 during botanical exploration of Mt Gangan, Kindia, Republic of Guinea in West Africa. The Mt Gangan area is known for its many endemic species including the only native non-neotropical Bromeliaceae Pitcairnia feliciana. Kindia is the fourth endemic vascular plant genus to be described from Guinea. Based on chloroplast sequence data, the genus is part of Clade II of tribe Pavetteae. In this clade, it is sister to Leptactina sensu lato (including Coleactina and Dictyandra). K. gangan is distinguished from Leptactina s.l. by the combination of the following characters: its epilithic habit; several-flowered axillary inflorescences; distinct calyx tube as long as the lobes; a infundibular-campanulate corolla tube with narrow proximal section widening abruptly to the broad distal section; presence of a dense hair band near base of the corolla tube; anthers and style deeply included, reaching about mid-height of the corolla tube; anthers lacking connective appendages and with sub-basal insertion; pollen type 1; pollen presenter (style head) winged and glabrous (smooth and usually hairy in Leptactina); orange colleters producing a vivid red exudate, which encircle the hypanthium, and occur inside the calyx and stipules. Kindia is a subshrub that appears restricted to bare, vertical rock faces of sandstone. Fruit dispersal and pollination by bats is postulated. Here, it is assessed as Endangered EN D1 using the 2012 IUCN standard. High resolution LC-MS/MS analysis revealed over 40 triterpenoid compounds in the colleter exudate, including those assigned to the cycloartane class. Triterpenoids are of interest for their diverse chemical structures, varied biological activities, and potential therapeutic value.

Pollen transfer efficiency of <i>Apocynum cannabinum</i> (Apocynaceae): a comparative perspective

Pollen transfer efficiency (PTE), the percentage of removed pollen delivered to conspecific stigmas, has been implicated in the morphological evolution, population dynamics, and lineage diversification of flowering plants. Pollinia, the aggregated contents of pollen sacs, present in Apocynaceae subfamilies Asclepiadoideae (milkweeds), Secamonoideae, and Periplocoideae and orchids (Orchidaceae), are the pre-eminent example of a plant trait that elevates PTE (to ca. 25%). However comparison of species with pollinia to “average” flowers (PTE ca. 1%) may over-estimate the gains from pollinia. We hypothesize that elevated PTE evolved in Apocynaceae prior to pollinia. We measured PTE and pollen to ovule ratio, a possible correlate of PTE, in Apocynum cannabinum, a milkweed relative with pollen tetrads (instead of pollinia) and simple bands of style head adhesive (instead of complex pollinium-carrying translators), comparing them to reports of other species collated from the literature. PTE of A. cannabinum is 7.9%, in the 24th percentile of reports for 35 milkweed species, but more than twice the highest PTE reported for a species with monads (3.4%). The bands of style head adhesive are functionally equivalent to the translators of milkweeds. The pollen to ovule ratio of A. cannabinum, at 19.8, is in the 94th percentile of ratios reported for milkweeds (mean 9.6). Our results are consistent with the hypothesis that floral novelties of Apocynaceae that evolved prior to pollinia also promote aggregated pollen transport and elevated PTE.

Systematics and character evolution of Vinceae (Apocynaceae)

AbstractVinceae comprises 9 genera and about 153 species. The genera differ greatly in a number of morphological traits, especially those relating to fruit and seeds, which resulted in their placement in different tribes and/or subtribes by earlier taxonomists. Here, 378 new chloroplast DNA sequences from 98 species from 5 tribes of the rauvolfioid grade were analyzed phylogenetically to test the monophyly of Vinceae, its 6 subtribes, and constituent genera, as well as the sectional treatments of Rauvolfia, and to find morphological synapomorphies for major clades. Vinceae, as currently circumscribed, was found to be monophyletic as were four of the six subtribes. Kopsia and Ochrosia were confirmed as successive sister groups to the rest. All nine genera currently recognized in the tribe were resolved as monophyletic, Laxoplumeria and Tonduzia for the first time. The broad circumscription of Petchia and Ochrosia proposed by previous authors was supported. The pantropical genus Rauvolfia is divided into two major lineages: one comprised entirely of paleotropical species, and the other the neotropical species, a recurring geographic pattern in the family. Surprisingly, the Hawaiian species of Vinceae have probably arisen by two different trans‐oceanic routes, either by long‐distance dispersal from Australasian (Ochrosia spp.) or Caribbean (Rauvolfia sandwicensis) ancestors. Within Rauvolfia, most of the sections, series and subseries recognized in previous classifications are paraphyletic. Only 2 of the 14 sections of Rauvolfia proposed by Pichon and 1 of the 11 sections proposed by Rao that are not monospecific were found to be monophyletic. Mapping of 30 morphological characters onto the molecular tree identified an unlobed upper wreath on the style head as an unambigous synapomorphy characterizing the tribe as well as synapomorphies for each of its genera. The two earliest‐branching genera, Kopsia and Ochrosia, have dextrorse corolla lobe aestivation, in contrast to the sinistrorse corollas of the other Vinceae and the great majority of genera throughout the rauvolfioid grade. Drupes have arisen in parallel at least three times within Vinceae. The adaptations of the endocarp for water dispersal are possibly ancestral in the tribe, and the observed morphological differences between the drupaceous fruits of Kopsia/Ochrosia versus Petchia and Rauvolfia may be due to their abiotic versus biotic dispersal mode, respectively.

Floral development of Condylocarpon isthmicum (Apocynaceae)

Apocynaceae is one of the largest families of angiosperms. Its representatives have flowers with relatively simple morphology, ranging from anthers free from the style head to more complex flowers in which the anthers are postgenitally united with the style head, forming a gynostegium, and those with a style head that is vertically differentiated into distinct functional regions. The aim of this study is to understand the morphology and secretory structures of Condylocarpon isthmicum (Vell.) A.DC. at different stages of development. This species, which is in the family Apocynaceae, has morphologically simple flowers. Flowers at four different stages of development were collected and processed for anatomical and histochemical analysis; floral anatomy was examined using light and scanning electron microscopy. The simplicity of the C. isthmicum flower morphology was contrasted with the complexity observed in the secretory structures at different stages of flower development. Four secretory structures were identified in this species: colleters, style head epidermal cells, nectariferous tissue, and an obturator. The colleters were observed in the bracts and bracteoles of the young inflorescences. The style head began the secretory phase in the pre-anthetic stage and remained in this phase until anthesis. The nectariferous tissue was secreted during anthesis, and the obturator was present only in post-anthetic flowers. We identified a nectary in the wall of the ovary, and we verified and described a new structure in the Apocynaceae, the obturator.

Secretory Tissues and the Morphogenesis and Histochemistry of Pollinarium in Flowers of Asclepiadeae (Apocynaceae)

Premise of research. Flowers of some Apocynaceae present an unusual synorganization among parts and organs, which has led to the origin of new organs and a type of pollen dispersal and pollination unique to eudicots. The synorganization of androecium and gynoecium allowed the evolution of the pollinarium, a very complex and species-specific structure composed of pollen grains (pollinium) and secretions produced by the style head (translator). The aim of this study was to investigate the structure and activity of the secretory system related to the morphogenesis of pollinaria and the composition of their secretions in flowers of Asclepiadeae.Methodology. Flowers and buds of Asclepias, Gonioanthela, Matelea, and Oxypetalum were fixed, embedded in Paraplast, and sectioned in a rotary microtome for analysis under light microscopy. SEM was performed for additional structural data, and histochemical tests were carried out to reveal the main chemical composition of the secretions involved in pollinaria morphogenesis.Pivotal results. In the four species of Asclepiadeae studied, the style head possesses a palisade secretory epidermis that is responsible for the secretion of the translator, which is composed of a corpusculum and two caudicles. Mucilage, fatty acids, phenolic compounds, and proteins were detected in the corpusculum, whereas only neutral lipids and mucilage were present in the caudicles. In the anthers, tapetal cells are involved in the secretion of lipids that cover the whole pollinium. Just before anthesis, anthers dehisce, and the pollinia from adjacent anthers contact and adhere to the caudicles of the translator, forming the pollinarium.Conclusions. The translator shape is due to the differential activity of the secretory cells, which are spatially and temporarily coordinated, as well as the amount and composition of the secretion and the undulated outline of the secretory surface. The corpusculum and caudicles are composed of different chemical substances, and these features are related to the processes of removal and insertion of pollinia.

High specialisation in the pollination system of Mandevilla tenuifolia (J.C. Mikan) Woodson (Apocynaceae) drives the effectiveness of butterflies as pollinators

Butterfly pollination in the tropics is considered somewhat effective or solely effective in a few plant species. In the present study, we tested the hypothesis that Mandevilla tenuifolia (Apocynaceae), which has floral attributes associated with psychophily, has strategies adapted to pollination by butterflies, restricting other floral visitors and making these insects act as efficient pollinators. We analysed the floral and reproductive biology of M.tenuifolia, as well as the frequency and efficiency of its flower visitors. M.tenuifolia is an herb whose flowers have strong herkogamy and secondary pollen presentation on the style head, which corresponds to 60.4% of pollen on the anthers. Flower longevity and the long period of receptivity of the stigmatic region associated with the large amount of pollen removed in the first visits suggest that flowers remain functionally female during part of anthesis. Butterflies, mainly of the families Nymphalidae and Pieridae, are the only pollinators of M.tenuifolia. Despite being self-compatible, M.tenuifolia depends on biotic vectors for fruit production. A non-significant difference in fruit set between controlled treatments and natural conditions suggests that the pollinators are efficient. The inclination resulting from the landing of butterflies on flowers, together with flower morphology, guiding the insect proboscis inside the floral tube, as well as the frequency and efficiency of butterfly visits, are evidence of the close relationship between butterflies and M.tenuifolia, and also of the efficiency of these insects as pollinators.

Breeding system and fruit set in African Marantaceae

Marantaceae are a pantropically distributed family of perennial herbs and lianas in the understory of tropical rainforests. They are characterized by a unique pollen transfer mechanism. To understand its functional significance and evolution, field investigations have been conducted in Gabon.Data from 28 (of 35) species from Central Africa are achieved. The pollen–ovule ratio (34–140:1; exception Sarcophrynium 2.5:1) falls into the range of facultative autogamous species. All investigated species were proven to be self-compatible; however, only two were autogamous. Natural fruit set was generally low (10.9±10%). The highest natural fruit set was found in Marantochloa purpurea (29.7%), Ma. grandiflora (33.5%) and the two autogamous species Halopegia azurea (31%) and Marantochloa leucantha (35%). Considerable higher fruit set could be reached in all species by hand-self-pollination.We conclude that autogamy is generally avoided through herkogamy based on secondary pollen presentation on the back of the style head – a central component of the specific pollen transfer mechanism. However, with respect to the consecutive visit of pollinators to several flowers of the same individual geitonogamy cannot be excluded. The aggregated pollen transfer via the explosive pollination mechanism might be interpreted as an adaptation to low pollinator visitation rate, pollen limitation might explain the low fruit set.

Floral biology and a pollinator effectiveness test of the diurnal floral visitors of Tabernaemontana undulata Vahl. (Apocynaceae) in the understory of Amazon Rainforest, Brazil

In this paper we examined the floral biology, per-visit effectiveness, frequency of visits and relative abundance of the diurnal floral visitor taxa of T. undulata (Apocynaceae) at two populations located in the primary forest and in a disturbed area connected to the continuous forest. Its hermaphrodite flowers show a long and narrow floral tube and introrse anthers form a cone around the apex of the style head where the pollen is deposited. The stigmatic head has three functional regions, in a complex pollination mechanism favoring cross-pollination. In the pollinator censuses conducted in the primary forest population we registered Eulaema bombiformis. In the disturbed area Euglossa sp. was responsible for visits on T. undulata fl owers. Eulaema bombiformis was not absent in the disturbed area, but preferred to forage on pollen and nectar-rich flowers of two neighboring flowering species. In the primary forest, T. undulata was the only fl owering treelet at the end of the dry season. Signifi cant differences were not observed regarding the frequency of visits and relative abundance among the diurnal flower visitors at both sites. In the per-visit effectiveness experiment among flower visitors, we observed one fruit produced aft er E. bombiformis' visits. Due to the complex breeding system of T. undulata in that it is characterized by very low fruit production even under natural conditions, an indirect measure of pollinator effectiveness is needed in at a future stage of this study in order to clarify the role of these bee species as pollinators of T. undulata.

Fenologia reprodutiva, biologia floral e polinização de Allamanda blanchetii, uma Apocynaceae endêmica da Caatinga

(Fenologia reprodutiva, biologia floral e polinizacao de Allamanda blanchetii, uma Apocynaceae endemica da Caatinga). A fenologia reprodutiva, a biologia floral, o mecanismo de polinizacao e o sistema reprodutivo de Allamanda blanchetii A.DC. foram analisados em populacoes naturais na Fazenda Almas, Paraiba, Brasil. Allamanda blanchetii e uma especie arbustiva, endemica da Caatinga, com floracao de fevereiro a julho e pico nos meses de marco e abril. A frutificacao acompanhou a floracao e estendeu-se ate o mes de setembro. As flores sao tubulares e de coloracao rosa, cuja forte hercogamia evita a autopolinizacao. O polen e depositado na parte superior da cabeca do estilete (regiao nao receptiva), ainda na fase de botao em pre antese (anteras deiscentes), caracterizando a apresentacao secundaria de polen. As flores produzem uma media de 36,6 µL de nectar, o qual e o unico recurso para os visitantes florais. Allamanda blanchetii e auto-incompativel e os resultados sugerem mecanismo de incompatibilidade de acao tardia. Seus atributos florais estao relacionados com as sindromes de melitofilia e psicofilia e, de fato, os polinizadores registrados foram a abelha Eulaema nigrita Lepeletier como principal polinizador e quatro especies de borboletas que atuam como polinizadores secundarios. A ocorrencia de forte hercogamia, apresentacao secundaria de polen e mecanismo de auto-incompatibilidade indicam o elevado grau de especializacao dos sistemas de polinizacao e reproducao de A. blanchetii.

Systematics and character evolution of Tabernaemontaneae (Apocynaceae, Rauvolfioideae) based on molecular and morphological evidence

AbstractTabernaemontaneae (Rauvolfioideae, Apocynaceae) are small trees with mainly animal–dispersed fleshy fruits and arillate seeds represented in the tropics of Africa, Asia, the Pacific and America. The tribe is characterized by complex indole alkaloids, thus its species play a prominent role in traditional medicine. Taxonomically, the Tabernaemontaneae have a convoluted history fraught with contention as to tribal, subtribal, generic and sectional delimitation, with some authors recognizing Ambelanieae and Macoubeeae as separate tribes and others including them in an expanded Tabernaemontaneae s.l. In the species–rich pantropical genusTabernaemontana, seven sections and up to 30 segregate genera have been described during the past 100 years, giving it the dubious distinction of being the most disputed genus in Apocynaceae s.str. Here 420 new chloroplast DNA sequences from 104 species, including representatives of all satellite genera ever recognized in the Tabernaemontaneae, were analyzed phylogenetically to evaluate previous circumscriptions of Tabernaemontaneae and test the sectional treatment ofTabernaemontana. The Tabernaemontaneae s.l. as currently circumscribed was shown to be monophyletic. Of the 19 genera recognized in the most recent classification, 15 are maintained. The generaBonafousia, Stemmadenia, StenosolenandWoytokowskiaare nested withinTabernaemontana. Of the seven current sections ofTabernaemontana, the four that included taxa from more than one continent were found to be para– or polyphyletic. All natural groups recovered withinTabernaemontanawere found to correspond to geographic areas. Mapping of 29 selected morphological characters onto the molecular tree recovered recurrent suites of co–occurring character states and identified three synapomorphies characterizing the Tabernaemontaneae s.l.: (1) specialized anthers with massive lignified guide–rails; and a differentiated style–head with (2) a five–lobed upper crest and (3) a thickened basal flange. A new combination for the subtribe Ambelaniinae and the necessary new combinations resulting from mergingStemmadeniaintoTabernaemontanaare made.

The gynoecium of male Anchietea pyrifolia (Violaceae): Preserved structure with a new function

Structure of inflorescences and flowers and flowering behaviour are reported for the woody liana Anchietea pyrifolia (Violaceae) from Brazil. The specimen studied is grown for some decades now in the greenhouses of Halle Botanical Garden and turned out unisexually male, which adds a further example of dioecism to the family Violaceae, in which this type of sex distribution is rarely encountered. The flowers are exceptional also for the strongly asymmetric anterior petal, which represents a rare case of a species with enantiomorphic flowers pollinated by Lepidoptera. They have a fully developed gynoecium with a complicated architecture comparable to the pistil of bisexual Violaceae flowers, though without ovules. The style head is capable to release viscose liquid on tactile stimulation or pressure, which is known to act as pollen-gathering mechanism in bisexual Violaceae species with usually dry pollen and buzz-pollination. This function has switched in male A. pyrifolia to a mechanism for efficient pollen release mediated by insect pollinators from its short-lived flowers.

Gynostegium Morphology of Mesechiteae Miers (Apocynaceae, Apocynoideae) as It Pertains to the Classification of the Tribe

In order to investigate morphological patterns in Mesechiteae and test the new circumscription of the tribe, the gynostegium structure of nine species belonging to Forsteronia, Mandevilla, and Mesechites, with two species from Secondatia as outgroup, were comparatively studied. Our results support the most recent circumscription of Mesechiteae, including Forsteronia, Mandevilla, and Mesechites and excluding Secondatia. The gynostegia of Forsteronia, Mandevilla, and Mesechites have the same basic organization: a proliferation of parenchyma cells in the style head forms five projecting ribs that are adnate to an expanded portion of the connective below the thecae, here named the “staminal retinacle.” This adnation is very tenuous in Forsteronia (few cells of the staminal retinacle are effectively connected to the style head) but much stronger in Mandevilla and Mesechites (several cells of the staminal retinacle are connected to the style head). The observed differences in the size of the style head ribs and...