CHAPTER I. 



Graminese (Grasses). 



GENERAL DESCRIPTION. 



Fibrous-rooted annual or perennial, herbaceous (rarely woody) 

 plants, with usually hollow, cylindrical (rarely flattened), and jointed 

 stems (culms) whose internodes for more or less of their length are 

 enveloped by the sheath-like basal portion of the two-ranked and 

 usually linear, parallel-veined leaves; flowers without any distinct 

 perianth, hermaphrodite or rarely unisexual, solitary or several to- 

 gether, in spikelets, which are arranged in panicles, racemes, or spikes, 

 and which consist of a shortened axis (the rachilla) and two or more 

 chaff-like, distichous, imbricated bracts (glumes), of which the first 

 two, rarely one or none or more than two, are empty {empty glumes) ; 

 in the axil of each of the succeeding bracts (excepting sometimes the 

 uppermost) is borne a flower (hence these are named flowering 

 glumes). Opposed to each flowering glume, with its back turned to- 

 ward the rachilla, is (usually) a two-nerved, two-keeled bract or pro- 

 phyllum (the palea), which frequently envelops the flower by its in- 

 folded edges. At the base of the flower, between it and its glume, are 

 usually two very small hyaline scales (lodicules) ; rarely there is a third 

 lodicule between the flower and the palea; stamens, usually three (rarely 

 two or one, or more than three) with very slender filaments and two- 

 celled, usually versatile anthers; pistil with a one-celled, one-ovuled 

 ovary, and one to three, usually two styles with branched, most fre- 

 quently plumose, stigmas ; embryo small, lying at the front and base of 

 the seed, covered only by the thin pericarp; fruit a caryopsis, rich in 

 albumen. (In Sporobolus and Eleusine the thin pericarp is free from 

 the seed.) 



There are about 3500 species of grasses. The number given by 

 Bentham & Hooker 1 is from 3100 to 3200, but Hackel 2 gives the num- 

 ber about 3500, the latter number probably being more nearly correct, 

 considering that new territory is being explored, and new species are 



'Gen. PI. 3: 1074. 



2 Nat. Pf lanz. Fam II. 2 : 16. 



