EPIDERMAL CHARACTERISTICS OF THE CALLUS IN ERIOCHLOA (POACEAE)

A callus or cup at the spikelet base in Eriochloa is a diagnostic character for this genus. In an investigation of Eriochloa and related genera, the callus epidermis of 19 taxa of Eriochloa and the basal portion of Axonopus, Brachiaria, Digitaria, Leptoloma, and Panicum spikelets were examined with a scanning electron microscope. Eriochloa taxa were divided into three types based on callus epidermal characteristics. The callus of E. polystachya more closely resembled the reduced first glume in other panicoid genera than the callus in other taxa of Eriochloa. Bicellular microhairs, silica bodies, and interlocking long cells support the concept that the callus in Eriochloa is in part a remnant of the first glume.