Mandevilla

Abstract: (1) Dispersal of pollen by hummingbirds in two plant species, Mandevilla hirsuta (Apocynaceae) and Justicia secunda (Acanthaceae), was investigated on Trinidad, a large continental island, and Tobago, a smaller island with fewer species of hummingbirds. (2) Frequencies of hummingbird visits to flowers of each species (and, in Justicia, to flowers at different densities) on each island were quantified over a 13-month period. (3) During February 1978, pollen dispersal on each island was monitored with fluorescent powders, and fruit-set of Mandevilla was recorded. (4) In Justicia, which has a relatively open corolla accessible to many hummingbirds, frequencies of bird visits were similar on both islands. Patterns of total pollen dispersal, relating to labelled pollen deposited on any flower part, were also similar on both islands. Patterns of pollen deposition on reproductive parts were affected by feeding behaviour of the hummingbirds. (5) On Trinidad, Justicia pollen was dispersed less far from flowers defended by territorial hummingbirds than from undefended flowers. (6) Mandevilla, which has a long corolla accessible to only a few hummingbird species, received consistent visits from two hummingbirds 'constant' to that species at one Trinidad site. (7) On Tobago, where these 'constant' hummingbird species were absent, visits to Mandevilla were sporadic and were made only by species that fed on many plant species, and were not 'constant' on Mandevilla. (8) Accordingly, pollen dispersal of Mandevilla on Trinidad was extensive, with dye from marked flowers reaching most other flowers in the population on a given day, whereas on Tobago dye was dispersed only very short distances. (9) Fruit-set in Mandevilla on Tobago was significantly lower than on Trinidad. (10) These results support the prediction that a generalized plant such as Justicia would be affected less by an island-induced reduction in pollinatordiversity than would a specialized plant such as Mandevilla.

Abstract: Development, structure and distribution of colleters in Mandevilla illustris and M. velutina (Apocynaceae)). Colleters of Mandevilla illustris and M. velutina are present on the cotyledons, shoot apices, mature leaves and on the nodal region, where they are interpetiolar and intrapetiolar. In M. velutina there are two colleters on the adaxial basal part of the leaf blade, and in M. illustris, this number varies. The differentiation of the colleters occurs in the early stages of leaf development. When colleters are mature, they consist of a long head on a short stalk. The central core of the colleter is made up of parenchymatous cells that may exhibit phenolic compounds and is surrounded by radially elongated epithelial cells. The foliar and intrapetiolar colleters can exhibit vascularization. The colleters produce a translucient sticky substance that reacts positively to polysaccharides and, before senescence, they produce lipophilic substances. The Mandevilla colleters data can give support to the taxonomy and phylogeny of the Apocynaceae. RESUMO - (Desenvolvimento, estrutura e distribuicao de coleteres em Mandevilla illustris e M. velutina (Apocynaceae)). Coleteres de Mandevilla illustris e M. velutina estao presentes nos cotiledones, apices caulinares, folhas maduras e na regiao nodal, onde estes sao interpeciolares e intrapeciolares. Em M. velutina existem dois coleteres na face adaxial da base da lâmina foliar, porem, em M. illustris este numero varia. A diferenciacao dos coleteres ocorre nos estagios iniciais do desenvolvimento foliar. Quando os coleteres estao maduros, eles consistem de uma longa cabeca sobre um curto pedunculo. A porcao central do coleter e constituida de celulas parenquimaticas que podem apresentar compostos fenolicos e e envolvida por celulas epiteliais radialmente alongadas. Os coleteres foliares e intrapeciolares podem exibir vascularizacao. Os coleteres produzem uma substância pegajosa e translucida que reage positivamente para polissacarideos e, antes da senescencia, eles produzem substâncias lipofilicas. As informacoes obtidas sobre os coleteres das Mandevilla podem fornecer subsidios aos estudos taxonomicos e filogeneticos das Apocynaceae.

Abstract: The Neotropical tribe Mesechiteae (Apocynaceae) is currently considered to include nine genera: Allomarkgrafia, Galactophora, Macrosiphonia, Mandevilla, Mesechites, Quiotania, Secondatia, Telosiphonia, and Tintinnabularia. Tribal and intergeneric relationships, however, are in dispute. To test the monophyly of the tribe and evaluate intratribal relationships, a maximum parsimony analysis was conducted based on DNA sequences from the plastid rpl16 intron, rps16 intron, and trnS-G intergenic spacer region as well as morphological data for 23 taxa of Mesechiteae and 11 taxa from other tribes of Apocynoideae. Mesechiteae, as currently circumscribed, was found to be polyphyletic. Only removal of Secondatia and Galactophora and inclusion of Forsteronia rendered the tribe monophyletic. Thus defined, Mesechiteae forms a strongly supported clade including seven genera in three subclades: the Mesechites subclade (comprising Tintinnabularia, Allomarkgrafia, and Mesechites), the Forsteronia subclade (containing only Forsteronia) and the Mandevilla subclade (comprising Macrosiphonia, Mandevilla, and Telosiphonia). Allomarkgrafia is nested in Mesechites. Macrosiphonia and Telosiphonia form two distinct monophyletic clades. Both, however, are nested in Mandevilla. Results suggest upholding the following genera in Mesechiteae: Allomarkgrafia, Forsteronia, Mandevilla, Mesechites, and Tintinnabularia. The status of Quiotania could not be evaluated.

Abstract: The developmental anatomy of the subterranean system in Mandevilla illustris (Vell.) Woodson and M. velutina (Mart. ex Stadelm.) Woodson (Apocynaceae)). Two species of Mandevilla from the savanna area of Sao Paulo State, Brazil were studied. These species have been prescribed as folk medicine as infusions or alcoholic extracts of the underground system for treatment of venomous snake bites. To explain the morphological nature of such a system, its ontogeny was described to determine which parts are involved in its formation. In both Mandevilla species examined, the underground system consists of a xylopodium whose basal region joins a tuberous root. RESUMO - (O desenvolvimento anatomico do sistema subterrâneo em Mandevilla illustris (Vell.) Woodson e M. velutina (Mart. ex Stadelm.) Woodson (Apocynaceae)). Foram estudadas duas especies de Mandevilla que ocorrem em areas de campos cerrados do Estado de Sao Paulo, Brasil. Essas especies tem sido prescritas na medicina popular como extrato alcoolico ou infusoes do sistema subterrâneo para o tratamento de picadas de cobras venenosas. Para explicar a natureza morfologica de tal sistema a sua ontogenese e descrita visando determinar quais partes estao envolvidas na sua formacao. Em ambas as especies examinadas, o sistema subterrâneo consiste de um xilopodio cuja regiao basal une-se a uma raiz tuberosa.