Diferenciação dos feixes vasculares e dos elementos traqueais no rizoma de algumas Cyperaceae

Abstract

Were analized the rhizomes of Bulbostylis paradoxa Ness, Cyperus giganteus Vahl, C. odoratus L., Fuirena umbellata Rottb. and Hypolytrum schraderianum Ness. The primary body results from activity of primary meristems and primary thickening meristem (PTM). Secondary growth occurs too, due to the activity of the secondary thickening meristem (STM). Collateral vascular bundles are formed from procambium and MEP in H. schraderianum, and amphivasal bundles in the other species. However, all of the vascular bundles having protophloem and protoxylem are originated from procambium. Phloem and xylem are formed from MES in a single vascular tissue. Vessel elements were present in the most of the stems in primary and secondary growth, exception to H. schraderianum that has only tracheids in the last one; this information supports the occurrence of secondary growth in Cyperaceae. The vessel elements show a great morphological variation; generally, vessel elements from the primary growth, are longer and tip of vessel elements are present. The vessel elements from secondary growth are shorter and show tip of vessel elements and branchings.