Caryopsis Micromorphology of Eleusine Gaertn. (Poaceae) and Its Systematic Implications
穇属颖果微形态及其系统学意义

Caryopsis micromorphological characteristics of nine species of Eleusine were studied using the scanning electron microscopy (SEM). The results showed that there were three types of ventral shapes in caryopses including oval, lanceolate, and oblong, two types of compression including dorsiventral and lateral, two types of ventral faces including flat and concave. The embryo proportion ranged from 0.29 to 0.58, and hilum proportion from 0.10 to 0.24. There were two types of surface sculpture including the verrucate simple sculpture and the compound reticulate sculpture composed by the regular spread of verrucae. The mean diameter of caryopsis foveola ranged from 0.57 μm to 1.31 μm with a density from 30 to 200 in 100 μm2. It can be concluded that caryopsis ventral shape, sculpture, and foveola are very useful characteristics for the identification of species and the inference of interspecific relationships in Eleusine. Because of the flat and concave ventral face, caryopses of Eleusine have relatively small bulk, therefore possibly aiding rapid development and maturation. All characters seem to be particularly valuable in climates of East Africa seasonal drought.