Anatomy of the xeromorphic leaves of Allamanda neriifolia, Thevetia peruviana and Vinca minor (Apocynaceae)

The histology of the xeromorphic leaves of Allamanda nerüfolia, Thevetia peruviana and Vinca minor have been examined by LM and SEM. The most important xeromorphic characters in the leaves are thick and cutinized outer cell walls of the upper epidermis, a thick and in A. nerüfolia highly sculptured cuticle and in V, minor a two–layered palisade chlorenchyma and fiber bundles in the veins. A considerable variation occurs in characters not considered xeromorphic. The oxalate crystals in A. nerüfolia and T. peruviana differ conspicuously from each other both in shape and location. The nonarticulated laticifers are branched and located on both sides of the vascular strands in A. nerüfolia and T. peruviana , while they are unbranched and confined to the abaxial side of thehveins in V. minor. In addition attention was paid to the petiole appendages observed in the three species. When young these formations are secretory in A. nerüfolia and T. peruviana and consequently constitute colleters. The histological differentiation of the leaves is also briefly described.     

Colleters in Turnera and Piriqueta (Turneraceae)

The anatomy of colleters was examined by light and scanning electron microscopy in 25 species of Turnera and nine species of Piriqueta. Based on morphology, four categories of colleters were recognized: standard, sessile, lachrymiform and trochleariform, all of which differ in shape and length/width ratio. They all have a similar anatomy: they consist of an axis of parenchymatous cells, sheathed by a palisade epidermis. The standard type is the most widespread in the studied taxa; the lachrymiform example was found in those species of Piriqueta with setiform glandular hairs; only one trochleariform example appeared in T: diffusa. The sessile type is considered to be a morphological transitional form between extrafloral nectaries and colleters. This is the first record of sessile, lachrymiform and trochleariform colleters. The anatomy of colleters is compared with other secretory structures such as glandular trichomes and extrafloral nectaries.     

Pollen morphology of Alstonia (Apocynaceae)

The pollen of Alstonia has been studied by light and scanning electron microscopy. The pollen grains are always colporate. Four distinct pollen types could be recognized. Type 1 (2‐aperturate) and type 2 (3‐aperturate) have rounded endopores, while type 3 (?<36 μm) and type 4 (?>49 μm) possess H‐endoapertures. Probably, all four types have harmomegathically inactive apertures and folding mesocolpia. Type 1 is found in five species of section Alstonia. The other species of this section and the monotypic section Winchia have type 2. The sections Dissuraspermum, Monuraspermum and Tonduzia have pollen type 3. This type may be subdivided on the basis of some minor (overlapping) features, which more or less segregate Dissuraspermum from Monuraspermum. Palynologically, the monotypic American section Tonduzia appears to be most related to the Malesian/Australian/Pacific sections Monuraspermum and Dissuraspermum, and not to the African species of section Alstonia.     

A systematic revision of Anechites (Apocynaceae)

Anechites Grisebach is a rarely collected genus of Apocynaceae indigenous to the Caribbean, Central America, and coastal northern South America. It is infrequent where it occurs and has a problematic taxonomic history. The genus is described and illustrated, its important morphological characters, history, and relationships are discussed, and a distribution map is provided.     

Pollen morphology and phylogeny of the Alyxieae (Apocynaceae)

The pollen of the tribe Alyxieae, including Alyxia , Chilocarpus , Condylocarpon , Lepinia , Lepiniopsis , Plectaneia and Pteralyxia , has been studied with light, scanning electron and transmission electron microscopy. It is characterised by relatively large, irregularly disposed and - unequal-sized pores. 2-porate grains are most common in the Alyxieae, and occur in all genera except for Condylocarpon . 1-, 3-, 4- and 5-porate pollen grains are less common. The orientation of the polar axis and the equatorial plane could not be determined in any of the genera. Within the Alyxieae, Chilocarpus and Plectaneia are the nearest to other Apocynaceae, showing an essentially similar exine ultrastructure. Alyxia , Lepinia , Lepiniopsis and Pteralyxia make up a derived group, characterised by large pollen grain size and a remarkable nexine structure. Pollen of Lepinia and Lepiniopsis might be derived on the basis of their fossulate-verrucate ornamentation. Condylocarpon pollen shows a deviating set of pollen features (tetrads, inaperturate, reduced exine) that suggest it to be neotenic. Pollen morphology supports preliminary results of cladistic analyses of chloroplast data, in which the tribe is a monophyletic group nested in a 3-colporate environment, Chilocarpus and Condylocarpon are sisters at the base of the tree, Plectaneia is sister to a clade made up by Alyxia , Pteralyxia , Lepinia and Lepiniopsis , of which Lepinia and Lepiniopsis are the most derived.     

A synopsis of the genus allomarkgrafia (Apocynaceae)

The nine species of the genusAllomarkgrafia are treated synoptically, with a review of their systematics and nomenclature. Two new species,Allomarkgrafia ecuatoriana andA. insignis, and a new combination,Allomarkgrafia campanulata, are proposed here.     

Development, Structure and Cytochemistry of Resin-secreting Colleters of Gardenia gummifera (Rubiaceae)

The structure, ontogeny and cytochemistry of stipular colletersof Gardenia gummifera are described. The repeated division ofa few adaxial protodermal and subprotodermal cells of the youngstipule and the subsequent elongation by the latter resultsin the formation of a standard-type colleter. A developed colleterhas outer palisade-like glandular cells covered by a continuouscuticle and inner layers of elongated columnar cells. Enzymelevels in the palisade-like epidermal cells in the colletersindicate their active role in secretion. The secretion is resinous,occurs in the young colleters, and accumulates between the cellsand the cuticle. The cuticle later ruptures and releases thesecretory product, which drenches the young shoot apex. Gardenia gummifera L, stipule, colleters, resin, ontogeny, cytochemistry     

Floral morphology and late-acting self-incompatibility inApocynum cannabinum (Apocynaceae)

Scanning electron and fluorescence microscopy were used to clarify some aspects of the floral morphology ofApocynum cannabinum. Insects are required for pollination, since the floral morphology prevents autogamy and minimizes intrafloral self-pollination. Flowers hand-pollinated with self-pollen never set fruit, but 10.6% of cross-pollinations produced fruit. Self-pollen did germinate, however, and produced abundant tubes that grew through the pistil and entered the ovule micropyles. The proportion of ovules penetrated by self- and outcross-pollen tubes was not statistically significantly different. These results suggest thatA. cannabium possesses late-acting self-incompatibility, similar to that in the closely related Asclepiadaceae.     

鸡骨常山属三个种的核形态

研究了鸡骨常山属（Alstonia）3个种的核形态,其中盆架树（A.rostrata）的核型属首次报道,3个种的体细胞染色体数目均为2n=42,且糖胶树（A.scholaris）和鸡骨常山（A.yunnanensis）的染色体数目同前人报道的2n=44不同。盆架树的间期核和有丝分裂前期染色体分别为棒状前染色体型和中间型,核型公式为2n=42=3M＋21m＋18sm,核型不对称性类型为2A型。糖胶树的间期核和有丝分裂前期染色体分别为球状前染色体型和中间型,核型公式为2n=42=14m＋24sm＋4st,核型不对称性类型为3A型。鸡骨常山的间期核和有丝分裂前期染色体分别为复杂染色体中央粒型和中间型,核型公式为2n=42=5m＋37sm,核型不对称性类型为3B型。根据核形态结果,结合形态学特征和已有的细胞学资料,初步讨论了该属几个种的系统位置及演化趋势。     

Anatomy and histochemistry of colleters in Roupelia grata (Apocynaceae)

The colleters of Roupelia grata are present on the petiole of the leaf, bract, bracteole and calyx. A mature colleter has a distinct head and a stalk. The parenchymatous central core is surrounded by epithelial cells. The senescence of the colleter occurs at its apex first and then proceeds towards the base.     

The Development, Structure and Function of Dendroid Colleters in Psychotria kirkii Hiern (Rubiaceae)

The dendroid colleters of the leaf nodulated Rubiaceous shrubPsychotria kirkii Hiern. have been studied with respect to theirdevelopment, structure and function. The colleters, which arisefrom the adaxial surface of stipules of apical and lateral shoots,secrete a protein/carbohydrate mucilaginous substance in whichis maintained a colony of leaf nodule bacteria. The colletersare multicellular and multiseriate, consisting of a two to fourcell thick stalk from which radiate up to 70 elongate secretorybranch cells. Cuticle envelops both stalk and branch cells inearly developmental stages and as secretory activity increasesthis cuticle is largely lost in two different ways. The majorpart is forced off the branch cell surface through the passageof a largely carbohydrate component of the mucilage which surroundsthe colleters: a second method of cuticle loss involves thepassage from the cell of small electron-translucent bodies whichbecome coated with cuticle as they exit the cell. The mucilagein which the bacterial cells are found provides a vehicle wherebythe bacteria are able to enter the leaves, thus leading to theinitiation of leaf nodules. Psychotria kirkii Hiern., secretory dendroid colleters, symbiosis, ultrastructure, trichome development     

灯台树根的止咳活性成分

灯台树(Alstonia scholaris)属夹竹桃科(Apocynace-ae)鸡骨常山属植物,主要分布于台湾、湖南、广东、广西和云南。在西双版纳地区傣族人民将其作为止咳药而广泛应用(赵世望和刀正员,1980)。灯台叶曾收载于《陆川本草》、《云南中草药选》、《中华人民共和国药典》(1977年版一部     

Corona and anther skirt in Hoya (Apocynaceae, Marsdenieae)

The so called revolute margins of the corona in the genus Hoya (Marsdenieae) are homologous to the anther skirt. The anther skirt is primarily formed of two latero-basal lobes of the anther. In Hoya these lobes are fused with the underside of the basal process of the staminal corona and have evolved into a dominant structure of the gynostegium. Embedded in the anther skirt is the nectar tube, formed by the basal elongation of the guide rail. In many species, however, the function of nectar secretion for pollinator reward has been transferred to the anther skirt beneath the basal process of the corona. A survey of the Marsdenieae shows that the potential for developing an anther skirt is present in several other genera as well, though nowhere has it evolved into such elaborated structures as in Hoya.     

Neoteny, evolution and the New Zealand Parsonsia hybrids (Apocynaceae)

The striking diversification of leaf shape in juveniles of the hybrids between Parsonsia heterophylla A. Cunn. and P. capsularis (Forst. f.) R. Br. is described and illustrated. The applicability of Turing's diffusion reaction theory of morphogenesis was tested, and it was found that the diversity could be explained as a result of interactions between sine-wave-like gradients of morphogens in the leaf primordia. Precession in the onset of sexual maturity leads to the fixation of juvenile leaf characters. This neotenic process combined with natural selection may then lead to speciation and adaptive radiation, as in the Australian Parsonsia spp. The operation of these processes in other New Zealand genera and in Australian Proteaceae is discussed in relation to adaptive radiation and evolution.     

First record of simuliidae (Diptera) with pollinaria of asclepiadoideae (Apocynaceae) attached

The presence of pollinaria of two species of Asclepiadoideae (Apocynaceae), possibly Tassadia cf. martiana Decne. and T. cf. obovata Decne., attached to the mouth parts of simulid black flies [Cerqueirellum amazonicum (Goeldi), C. argentiscutum (Shelley & Luna Dias), C. oyapockense (Floch & Abonnenc), and Cerqueirellum sp.] are reported for the first time. The frequency and distribution of simulids recorded with pollinaria suggest that removal of pollinaria by these flies is not casual. Simulids probably use nectar in flowers of Asclepiadoideae as source of sugar, being able to remove their pollinaria. This finding demonstrates that simulids are not only vector of pathogenic parasites, but also carry pollinaria, and thus may represent a group of pollinators for species of Asclepiadoideae with small flowers.     

Generic delimitations in tuberous Periplocoideae (Apocynaceae) from Africa and Madagascar

BACKGROUND AND AIMS: The number of genera included in Apocynaceae subfamily Periplocoideae is a matter of debate. DNA sequences are used here as an independent dataset to clarify generic relationships and classification of the tuberous periplocoid genera and to address the question of the phylogenetic interpretation of pollinia formation in Schlechterella. METHODS: Representatives of nearly all African and Malagasy genera of Periplocoideae possessing root tubers were analysed using ITS and plastid DNA sequence characters. RESULTS: Sequence data from non-coding molecular markers (ITS of nrDNA and the trnT-L and trnL-F spacers as well as the trnL intron of plastid DNA) give support for a broad taxonomic concept of Raphionacme including Pentagonanthus. Together with Schlechterella, which is sister to Raphionacme, all Raphionacme-like taxa form a derived monophyletic group of somewhat diverse species. Sister to the Schlechterella/Raphionacme clade is a clade comprising Stomatostemma and the not truly tuberous vine Mondia. In the combined analysis, sister to these two clades combined is a clade formed by Petopentia natalensis and Periploca. CONCLUSIONS: The recent inclusion of the monotypic South African Petopentia in the monotypic Malagasy endemic Ischnolepis is to be rejected. The Malagasy Camptocarpus is sister to the remainder of Periplocoideae in the ITS and combined analyses, and a Malagasy origin for the subfamily is discussed.