Morphology and anatomy of the vegetative organs and scapes from Aphorocaulon (Paepalanthus, Eriocaulaceae)

Abstract

The roots, stems, scapes and leaves anatomy of species of Paepalanthus subsect. Aphorocaulon were studied. The plants showed short stems with rosulate leaves and possessed an aerial axis branching, the paraclades. These species had roots with uniseriate epidermis and cortex with isodiametric cells. Short stems and paraclades presented a thickening resulting from the activity of the pericycle named prymary thickening meristem (PTM). They presented a similar anatomical feature. The scapes presented discontinuous endodermis, sinuous pericycle, and the cortex had proeminent ribs (5-6) and the leaves showed epidermis with elongated cells in the longitudinal orientation, cell walls slightly thickened, stomata present only on the abaxial surface, with special leaf substomatal chambers, collateral vascular bundles with a double sheath. Those anatomical characteristics are common to Aphorocaulon species and are those typical of plants that grow in the rupestrian field habitats.