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

Ae roots, stems, scapes and leaves anatomy of species of Paepalanthus subse ct. Aphorocaulon were studied, The plants showed short stems with rosulate leaves and possessed an aerial axis branching, the paraclades. These specie s had roots with uniseriate epidermis and cortex with isodiametric cells. S hort stems and paraclades presented a thickening resulting from the activit y 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 leave s showed epidermis with elongated cells in the longitudinal orientation, ce ll walls slightly thickened, stomata present only on the abaxial surface, w ith special leaf substomatal chambers, collateral vascular bundles with a d ouble sheath. Those anatomical characteristics are common to Aphorocaulon s pecies and are those typical of plants that grow in the rupestrian field ha bitats.