938 THE GRASS FAMILY. 



ing glume and palea. Many botanists restrict the name of glume to 

 the outer empty pair, calling both the flowering glumes and their palea, 

 paleas or glumellas, and giving the name of sterile florets to all other 

 empty glumes in the spikelet, or even to a small prolongation of the 

 axis which is often observable at the outer base of the palea of the 

 terminal flowers. The leaves of Grasses are frequently described as 

 convolute, that is, rolled inwards on the edges, but this character is 

 often very deceptive in dried specimens, for in many species the leaves 

 are perfectly flat when growing, but roll inwards in drying immediately 

 on being gathered. 



Grasses are abundantly diffused over the whole world, from the 

 utmost limits of phsenogamous vegetation towards the Poles or on 

 alpine summits, to the burning plains of the Equator. In temperate 

 regions they form the principal mass of the green carpeting of the soil, 

 whilst in tropical regions some species (the Bamboos) attain the height 

 of tall trees. They supply us with one of the most important articles 

 of food for man, in the shape of grain, and for cattle as constituting the 

 chief portion of meadows and pastures. 



., f Spikelets 1-flowered 2 



I Spikelets containing 2 or more flowers 24 



f Spikelets arranged along one side of a slender, simple, linear spike . . 3 

 I Spikelets arranged along one side of the simple linear branches of the 



. J panicle 5 



I Spikelets arranged in a close, cylindrical or ovate spike or spike-like 



panicle 7 



L Spikelets arranged in a loose, branching panicle 16 



Spikelets 1-jloivered, in one-sided linear spikes. 



I^Gmme 1 only, ending in a fine point, and enclosing the palea and flower 

 3-{ 24. Naed. 

 (JTwo outer empty glumes and a flowering one 4 



{Outer glumes 1 line long, thin and obtuse. Axis not jointed. 

 10. Chamageostis. 

 Outer glumes 2 lines long, stiff, and strongly ribbed. Axis jointed. 

 23. Lepttteus. 

 k f Spikelets in pairs or clusters along the branches .... 3. Panicum. 



I Spikelets single along the branches 6 



r Spikelets half an inch long, laterally flattened. Glumes all strongly 



6 { keeled, erect 22. Spaetina. 



I Spikelets about a line long. Outer glumes spreading . .21. Cynodon. 



Spikelets 1-Jlowered, in a dense spike or spike-like panicle. 



J* f Outer glumes without awns. Flowering glumes with or without awns 8 

 I All the glumes awned 13 



