RESUMO
It appears that up to now the inflorescence and flower morphologies of Atriplex halimus have been described incompletely. This species has been classified as monoecious or dioecious. Numerous observations and ontogenic studies have pointed to types of flowers morphologically and functionally hermaphroditic, never described until now. One specimen of this species presents both unisexual, male and female flowers and bisexual flowers, so Atriplex halimus is polygam and more precisely trimonoecious. Observation of inflorescences reveals a structure based on the spike and the dichasium. The sex distribution along the inflorescence axis was studied and the existence of a physiological gradient controlling its expression is discussed.
Assuntos
Magnoliopsida/classificação , Magnoliopsida/fisiologia , Magnoliopsida/ultraestrutura , Caules de Planta/ultraestrutura , Pólen/ultraestrutura , Reprodução , Sementes/ultraestruturaRESUMO
The family Asclepiadaceae (Dicotyledones) was created by Brown in 1810 by splitting in two the family Apocynaceae of Jussieu established in 1789. The morphological characters used to make this distinction were mainly palynological, such as presence of tetrads or pollinia and number and orientation of pollinia. Those characters, still used in higher taxonomic delimitation (families, subfamilies, and tribes), are here critically reexamined and compared to a molecular phylogeny obtained with one of the more variable plastid genes (matK) of 46 species in the order Gentianales. In this molecular phylogeny, Asclepiadaceae form a monophyletic group derived from within Apocynaceae. Each of the subfamilies of Asclepiadaceae is monophyletic and based on reliable palynological characters, but palynological characters are not useful to delimit tribes of the subfamily Asclepiadoideae. Based on the molecular data, these tribes have undergone parallelisms in several reproductive traits.