Lasiocephalus Willd. ex Schltdl. (Asteraceae-Senecioneae) present an diversity of growth forms, ranging from climbing to subcoriaceous subshrubs of narrow leaves, which all have a close relationship with the type of environment and...
moreLasiocephalus Willd. ex Schltdl. (Asteraceae-Senecioneae) present an diversity of growth forms, ranging from climbing to subcoriaceous subshrubs of narrow leaves, which all have a close relationship with the type of environment and habitat to which they belong. The subgeneric delimitation has historically been dependent on the biotype, however, currently reproductive morphological and molecular characters are proposed to define it. Anatomical characteristics of the leaf blade compared between species representative species of these biotypes, to define the infrageneric delimitation and so complement the new morphological proposals. The study was performed taking into consideration Lasiocephalus species present in Venezuela, L. cuencanus (Hieron.) Cuatrec., L. doryphyllus (Cuatrec.) Cuatrec., L. longipenicillatus (Sch. Bip. ex Sandwith) Cuatrec., L. otophorus (Wedd.) Cuatrec. (doubtful presence) and L. patens (Kunth) Cuatrec. The plant material was obtained from specimens collected in the field or fragments taken from herbarium exsiccatae, of which slides of cross sections and material macerated from the middle portion of the blade were prepared, subsequently observed, analyzed, and photographed. The taxonomic value for the subgeneric delimitation with the location of the stomata (amphistomatic or hipostomatic leaves) was verified. Interspecies relation is highlighted by trichome (number, size and relative thickness of the cells, in addition the shape of the basal cell), and the number of layers of palisade parenchyma and its relationship to the spongy parenchyma tissue. An artificial key for species determination is presented.
