700 SYSTEMATIC BOTANY. 



Fig. 1081. Fig. 1082. 



Fig. 1081. A portion of the stem of the CaPs-tail Grass {Phleum pratense), 

 hearing a leaf withparallel veins, and a split sheath.— — Fig. 1082. Dia- 

 gram of a spikelet of an Oat (Aijctwi). (From Maout.) gl,gl. Twoglumes, 

 enclosing two perfect flowers, and one, a, abortive, b-. The outer palea. 

 h, b. The inner palea, wliich seems to he formed of two united, p, p. 

 Two scales {squamulce or glumeUulcs) ; the dotted curved line on the 

 right marks the position of a third abortive scale, e. Stamens, c. 



Ovary. Fig. 1083. A spikelet (locusta) of the Oa.t (^ Arena sativa). ge. 



Outer gUime. gi. Inner glume, pe. Outer palea of the fertile flower, pi. 

 Inner palea of the same. e. Stamens, o. Ovary, /a, and a. Abortive 

 flowers. 



hairy {Jigs. 587 and 1084). Fruit a caryopsis (fgs. 688 and 

 689). Seed witli mealy albumen (Jig. 689, a) ; cmhryo lenticular 

 {Jig. 1087), lying on one side at the base of the albumen {Jig. 

 689, c,g, r). 



Distribution, cf'c. — Grasses are universally distributed over the 

 globe. In temperate and cold climates they are herbaceous 

 and of moderate height, while in tropical countries they become 

 shrubby and arborescent, and sometimes grow to the height of 

 60 or 60 feet. Grasses usually grow together in large masses, 

 and thus form the verdure of great tracts of soil; and hence 

 have been termed social plants. Examples of the Genera : — 

 Phalaris, Stipa, Arundo, Avena, Festuca, Triticum, Hordeum, 

 Saccharum. There are about 4,000 species. 



