Acta Botânica Brasílica (Sep 2009)
Anatomia de espécies anfíbias de Cyperaceae de lagoas do semi-árido, BA, Brasil Anatomy of amphibious Cyperaceae species from lakes in the semi-arid region of Bahia State, Brazil
Abstract
Foi estudada a anatomia de raízes, rizomas, folhas e escapos de Cyperus odoratus L., Oxycaryum cubense (Poep. & Kunth) Lye e Pycreus macrostachyos (Lam.) Raynal (Cyperaceae-Poales) de lagoas do semi-árido da Bahia visando caracterizar anatomicamente as espécies e levantar estruturas adaptativas à forma de vida anfíbia. As espécies apresentam raízes com epiderme unisseriada, córtex com exoderme e lacunas de ar. Os rizomas apresentam feixes vasculares anfivasais ou colaterais no cilindro vascular. As folhas apresentam epiderme unisseriada, com células de parede periclinal externa mais espessada que a interna, estômatos somente na face abaxial, parênquima clorofiliano alternado com lacunas de ar e feixes vasculares colaterais. Os escapos apresentam epiderme unisseriada, feixes de fibras distribuídos perifericamente alternados com parênquima clorofiliano, lacunas de ar e feixes vasculares colaterais. Oxycaryum cubense difere de Cyperus odoratus e Pycreus macrostachyos por apresentar raízes com pêlos longos, rizomas e estolões com feixes vasculares colaterais, folhas com bordo agudo, e ausência de estrutura Kranz nas folhas e escapos. Características anatômicas como: lacunas de ar observadas principalmente nas raízes, células buliformes na face adaxial da epiderme foliar, hipoderme, reduzido número de elementos xilemáticos e pouca lignificação nas paredes celulares dos tecidos nos diferentes órgãos estudados são consideradas importantes na adaptação dessas plantas anfíbias às lagoas temporárias do semi-árido da Bahia.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.
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