ECONOMIC IMPORTANCE OF GRASSES 



127 



FIG. 51. Timothy (Phleum pratense). A, single spikelet; B, spikelet with glumes 

 removed; C, pistil. (Robbins.) 



groove 



PIG. 52. PIG. 53. 



FIG. 52. Diagram of A, lily flower, and B, grass flower showing homologous struc- 

 tures. A, f, bract; ax, axis; op, outer part ot perigonium; ip, inner part of perigonium; 

 5, stamens; c, tricarpellary 3-celled ovary. B, shaded structures are aborted; le, glume 

 (bract); ax, axis; p, palet, and p', lemma (outer perianth); I and I' lodicules (inner part 

 of perigonium); 5 and s', two whorls of stamens; c, tricarpellary i-celled ovary. (B. 

 Robbins after Schuster.) 



FIG. 53. Part of a median lengthwise section of a grain of wheat; much enlarged. 

 (Robbins after Strasburger.) 



