Comparative anatomy of the vegetative organs of species of Bulbophyllum sect. Didactyle (Lindl.) Cogn. and Bulbophyllum sect. Xiphizusa Rchb.f. (Orchidaceae)

Bulbophyllum sect. Didactyle and B. sect. Xiphizusa are monophyletic and sister groups, inserted in the neotropical clade of the genus. The species occur as epiphytes or rupicolous in mountainous areas with predominance of rocky fields. This study aimed to comparatively describe the anatomy of the vegetative organs of 13 species of these sections. This work highlights for the first time the lipophilic secretion of trichomes in young leaves; uniform xeromorphic characters between species of the two sections as thick cuticle, presence of idioblasts, aquifer parenchyma, and fibers along the vascular bundles; absence of prismatic crystals in the root and pseudobulb in B. sect. Didactylespecies and absence of idioblast with spiral thickening in root, epidermis with thickening wall in pseudobulb and predominance of heterogeneous mesophyll leaves of species of B. sect. Xiphizusa, could be considered synapomorphic character state to the sections, showing the importance of the anatomy in systematic studies.

epiphytes; leaf anatomy; monocots; pseudobulb; root anatomy