Foliar anatomy of Rhynchosia spp. (Leguminosae, Papilionoideae) from Roraima state, northern Brazilian Amazon

ABSTRACT Comparative studies on the structure of foliar anatomy in four species of Rhynchosia from Roraima state (northern Brazilian Amazon) were carried out to identify additional morphological characters to support the definition of the systematic boundaries among the species. Fully expanded leaves, including the petioles, were collected from the upper nodes of a plant’s stem. Anatomical characters were observed in cross-sections of the middle portion of leaflets and petiole segments. Presence and distribution of glandular trichomes, continuity of sclerenchyma around the vascular bundles in leaflet blades and the conformation of the area between the two ridges of petioles were important characters to distinguish among the species of Rhynchosia. For the first time we report a distinct multicellular gland-like structure which we found in the petioles of three species.摘要：针对巴西北部亚马逊地区罗赖马州的4种鹿藿属（Rhynchosia）植物的叶解剖结构开展比较研究，旨在挖掘额外的形态学特征，以辅助明确该类群物种间的系统分类边界。本研究采集了植株茎部上位节位上完全展开的带叶柄叶片，通过对小叶中部及叶柄切段的横切片进行观察，获取解剖学特征。腺毛的有无与分布、小叶叶片中维管束周围厚壁组织的连续性，以及叶柄两脊之间区域的构型，均为区分该属物种的重要鉴别特征。本研究首次报道了在3个该属物种的叶柄中发现的一种独特的多细胞类腺体结构。