XVI International Botanical Congess

The leaf epidermis of Roegneria are very similar to Elymus by their common characters: 1). micro-hairs absent, 2). stomata with parallel-sided or low dome-shaped subsidiary cells, 3). silica bodies over the veins, sometimes tall, narrow, more or less rectangular, but more frequently round, elliptical, or sometimes horizontally elongated with sinuous outlines, 4). with short cells between long cells in abaxial surface, 5). costal zone narrow than the intercostal zone, 6). same shape and arrangement of long cells (margin entire, thin) between the veins etc. According to these same characters of leaf epidermis, Roegneria C. Koch should be referred to Elymus L. connected with their other same characters: chromosome number (x=7), genome(StH, StY, StHY), gross morphology [inflorescence spikelike, spikelet 1-2(-9) per node], distribution etc. According to the rule of priority (Intern. Code Bot. Nomencl.), Roegneria C. Koch should be referred to Elymus L.