Diversity of leaf epidermal structures used in biosystematics of rice species

Abstract

The rice genus contains 24 annual or perennial species, including two cultivated rice species, i.e., the Asian rice ( Oryza sativa L.) and African rice ( O. glaberrima Steud), and 22 wild species in the tropics. In this study, morphological features of the leaf epidermis of 22 rice species (see table) were observed by light microscopy to find characters for identifying species and to assess systematic relationships in the genus. For example, O. schlechteri, O. ridleyi, O. longiglumis, O. granulata, O. brachyantha, O. officinalis, O. minuta, O. sativa, O. nivara, and O. meyeriana have elliptic stomatal complexes, whereas in other species they are rhombic. The size of papillae on most epidermal surfaces ranged from small (1.5-4.4 μm diam) to medium (9-18 μm) to large (21-30 μm), and their size and distribution were very useful in identifying species. In addition, the number and location of the small papillae in stomatal complexes differed between species.