4 Bulletin VII. 1. 



tion, the lowermost joints being bent or kneed; such culms are 

 said to h^. geniculate at base. The basal branches may lie flat upon 

 the ground and spread more or less extensively, taking root at the 

 usually numerous joints, and at definite points sending up erect 

 flowering branches, or branches bearing leaves only; such grasses 

 are said to have a creeping habit, or are stoloniferous. Again, one 

 or more of the lowermost branches may not come to the surface at 

 all, or only after it has extended through the soil for a greater or 

 less distance. These form the "creeping roots" {rhizomes) of 

 grasses, but they are true stems or branches, for they are always 

 distinctly jointed, and at the joints there are scale-like leaves — 

 characters never found in true roots. The joints of these under- 

 ground stems may be very short, and from each node may spring 

 a flowering branch. So condensed may this growth be that the 

 rhizome is entirely concealed, but in perennial grasses it is always 

 present, and in the best turf or sward-forming grasses it is sufli- 

 ciently manifest. In couch-grass, and especially in Johnson grass, 

 these rhizomes are greatly developed, penetrating the soil in all 

 directions, forming a sward that is exceedingly difficult to break. 



Grass stems are usually round or cylindrical, rarely flattened, 

 and generally hollow between the joints or nodes (solid or with 

 pith in the Andropogons, Indian Corn, and a few other grasses). 

 The nodes, familiarly termed the joints, are the points on the 

 culm or its branches from which the leaves originate; they are 

 usually somewhat swollen, the enlargement being either in the 

 culm or, as is very often the case, in the basal part of the leaf- 

 sheath. The space between two nodes is the internode. All 

 branches, excepting those of the general inflorescence, originate 

 in the leaf-axils, that is, within and at the base of the leaf-sheaths, 

 and between the branch and the main axis or stem there always 

 is a longer or shorter two-keeled prophyllum with its back turned 

 towards the main axis. The presence of this prophyllum always 

 indicates the presence of a branch, although the branch may be 

 very much shortened, as in the case of the true floral axis where 

 this prophyllum is the palea. 



The Leaves. — The leaves of grasses have two distinct parts: the 

 sheath and the blade. The sheath, or basal portion, usually closely 

 surrounds the stem, and is split or open upon the side opposite the 

 blade, or is entire, then forming a closed cylindrical sheath {vagina) 

 about the stem. When split, the free edges usually overlap each 

 other. At the top of the leaf-sheath, at the point where the blade 

 originates, there is upon the inside usually a thin and delicate 

 prolongation, often very short, called the ligule. Sometimes the 

 ligule takes the form of a fringe of hairs. The leaf-blade is gen- 

 erally narrow, usually many times longer than broad, with nearly 



