Anatomy, macro- and micromorphology of Lathyrus sect. Nissolia (Fabaceae) and their taxonomic significance

Abstract

The present paper reports the results of studies on the macromorphological, anatomical, seed-coat surface, petal and sepal epidermal micromorphological characteristics of L. nissolia L., the only one member of the genus Lathyrus L. sect. Nissolia (J.Mill.) Dumort (Fabaceae) using light and scanning electron microscopy. The amended and expanded macromorphological description of the species is provided. According to the results, anatomical characters such as size of pith cells in the root, the presence/absence of wings on the stem, the presence of large parenchymatic cells in the center of the stem and mesophyll structure could provide information of taxonomic significance. Seeds were mainly globose, brown, 1.54–2.61 mm in length and 1.38–1.94 mm in width. Hilum was elliptic or ovate, 0.29–0.62 in length and 0.12–0.30 mm in width. The seed surface was falsifoveate–colliculate. Three types of petals (dorsal, lateral and ventral) had tabular rugose cells with longitudinal striations (TRS), but differed in cell size, cell shape, the pattern of anticlinal cell walls and density of striations on the surface. Sepals had irregular epidermal cells with a granulose sculpture. Three main types of trichomes (peltate, capitate glandular and non-glandular) were recognized on the sepals. The peltate and capitate glandular trichomes were rarely found while the non-glandular trichomes were abundantly distributed. The presence/absence, types, density and size of the trichomes and sculpturing pattern on the sepal could be potentially useful in separating different species of Lathyrus.