Structure of the Apices of Rhizomes and Aerial Shoots of some Temperate Range Grasses

In all eight species of range grasses studied, the cellular architecture of the apex tip of the young aerial (vertical) shoots is subject to variation. In any given species, the range of cellular patterns encountered probably largely depends on the number of apices examined Parallel variations can be found from species to species. Similar alternatives of construction can be found in the rhizome apices, and there is nothing to distinguish their architecture from that of aerial shoots. The variations in apical structure of both rhizomes and aerial shoots are not plastochronic. The number of leaf primordia "carried" on the apex can vary considerably in both aerial shoots and rhizomes, even of the same species However, despite wide variation in actual numbers, on the average, rhizome apices appear to "carry" about one primordium fewer than aerial shoots. It is evident that the use of apical architecture as a basis for classification in the Gramineae needs considerable caution.