Estudo Anatômico de Três Espécies do Gênero Ipomoea L. ocorrentes Na Restinga da Ilha de Algodoal/Maiandeua (P.A.)

Abstract

The family Convolvulácea Juss. contains about 51 genera and more than 1200 species (Barroso, 1986). In the Amazon, Austin & Cavalcante (1982) cite 132 taxa of this family. On the island of Maiandeua/PA, the family is represented by 2 genera and 9 species (Bastos, 1988). Among them, Ipomoea asarifolia (Desr.) Roemer & Schultes, Ipomoea pes-caprae (L.) R. Brow, and Ipomoea setifera Poir. were studied with the objective of providing information about the leaf anatomy to help in their botanical identification. The individuals were collected in the restinga of the Maiandeua Island, PA, and submitted to the usual techniques in a plant anatomy laboratory. In frontal view, the epidermis of the three species, in both surfaces, present heterodimensional epidermal cells, with a straight anticlinal wall in I. asarifolia and slightly sinuous in I.pescaprae and I. setifera. In all three species the stomas are paracitic and the leaves are amphistomatous. The cuticle on the epidermis is striated. Uni and pluricellular tector trichomes are observed in all species. The glandular trichomes are of the peltate type. In transverse section, the leaves of I. asarifolia, I. pes-caprae and I. setifera present collateral vascular bundles. The vascular elements present in the mesophyll are surrounded by a sheath of parenchymatic tissue without apparent content, organized radially. Conspicuous substomatic chambers are also observed in the mesophyll of I. asarifolia and I. pes-caprae, relative to those of I. setifera. The three species of Ipomoea present a dorsiventral mesophyll type. In I. pes-caprae and I. setifera the mesophyll is apparently homogeneous, due to the compactness of the lacunose tissue. The palisade tissue of I. asarifolia is formed by 3 to 5 layers of tightly packed cells, and the lacunose parenchyma consists of layers of 4 to 5 cells separated by intercellular spaces. In I. setifera the palisade parenchyma has 2 to 5 layers, while the lacunate parenchyma has 3 to 5 cell layers. We can point out as differentiating anatomical characteristics between the species: the anticlinal wall of the epidermal cells straight in I. asarifolia and sinuous in I. pes-caprae and I. setifera; the compactness of the lacunose tissue in the mesophyll of I. pes-caprae and I. setifera; and the presence of conspicuous substomatal chambers in I. asarifolia and I. pes-caprae.