GENERA OF GRASSES OF THE UNITED STATES. 5 



Any forage grass may be preserved in a silo, but corn is the one 

 most commonly used for this purpose. 



The most important lawn grasses are (1) in the North, bluegrass, 

 Rhode Island bent, and creeping bent; (2) in the South, Bermuda 

 grass, carpet grass, and St. Augustine grass. 



The ornamental grasses include the reeds, such as pampas grass 

 and eulalia ; border grasses, such as fountain grass and blue fescue ; 

 and variegated grasses, such as ribbon grass. 



Soil-binding grasses are species having vigorous rhizomes which 

 hold sand or other loose soil and prevent erosion by water or wind. 

 Banks are secured against water erosion by a covering of redtop or 

 Bermuda grass. The most important sand binder in use in this coun- 

 try is beach-grass (AimnophUa arenaria). This is planted upon 

 sand dunes to prevent wind erosion. 



The two sugar-producing grasses are sugar cane and the saccha- 

 rine varieties of sorghum. No textile grasses are cultivated in the 

 United States. The esparto grasses (Spartina tenacissima and 

 Lyyeum spartum) of Spain and Algeria furnish fiber for the 

 manufacture of paper and cordage. 



All these grasses are mentioned in the text under the proper genus. 

 (See index.) 



POACEAE, THE GRASS FAMILY. 



Flowers perfect (rarely unisexual), small, with no distinct peri- 

 anth, arranged in spikelets consisting of a shortened axis (rachilla] 

 and 2 to many 2-ranked bracts, the lowest two being empty (the 

 glumes, rarely one or both .of these obsolete), the one or more succeed- 

 ing ones (lemmas] bearing in their axils a single flower, and, between 

 the flower and the rachilla, a second 2-nerved bract (the palea), the 

 lemma, palea, and flower together constituting the floret; stamens 1 

 to 6, usually 3, -with very delicate filaments and 2-celled anthers; 

 pistil 1, with a 1-celled 1-ovuled ovary, 2 (rarely 1 or 3) styles, and 

 usually plumose stigmas; fruit a caryopsis with starchy endosperm 

 and a small embryo at the base on the side opposite the hilum. 



Herbs, or rarely woody plants, with usually hollow stems (culms) 

 closed at the nodes, and 2-ranked parallel-veined leaves^ these con- 

 sisting of 2 parts, the sheath, enveloping the culm, its margins over- 

 lapping or sometimes grown together, and the Made, usually flat; 

 between the two on the inside, a membranaceous hyaline or hairy 

 appendage (the liguZe) . 



The spikelets are almost always aggregated in spikes or panicles 

 at the ends of the main culms or branches. The perianth is usually 

 represented by 2 (rarely 3) small hyaline scales (the lodicules) at 

 the base of the flower inside the lemma and palea. The grain or 



