Anatomy of amphibious Cyperaceae species from lakes in the semi-arid region of Bahia State, Brazil

(Anatomy of amphibious Cyperaceae species from lakes in the semi-arid region of Bahia State, Brazil). We examined the anatomy of roots, rhizomes, leaves, and scapes of Cyperus odoratus L., Oxycaryum cubense (Poep. & Kunth) Lye, and Pycreus macrostachyos (Lam.) Raynal (Cyperaceae-Poales) from temporary lakes in the semi-arid region of Bahia in order to characterize the anatomy and examine structural adaptations to amphibious lifestyle. All species had roots with uniseriate epidermal cells, cortex with exoderm and air canals. The rhizomes had amphivasal or collateral vascular bundles in the vascular cylinder. The leaves had uniseriate epidermal cells with external periclinal cell walls thicker than the inner walls. stomata on the abaxial leaf surface, chlorenchyma alternating with air canals, and collateral vascular bundles. The scapes had uniseriate epidermal cells, fibrous groups distributed peripherally, alternating with chlorenchyma, air canals, and collateral vascular bundles. Oxycaryum cubense differs from Cyperus odoratus and Pycreus macrostachyos by having roots with long hairs; rhizomes and stolons with collateral vascular bundles; leaf blades with acute margins, and lacking Kranz structures in leaves and scapes. Anatomic characters such as the presence of large air canals principally in the roots, bulliform cells on the adaxial face of the leaf epidermis, hypodermis, reduced numbers of xylem vascular elements and little lignification of the cell walls of the different plant organs are considered important features in the adaptation of these amphibious plants that inhabit temporary lakes in the semi-arid region of Bahia state.