CLASS TRIAJSTDKIA. 



133 



on account of the shajoe of their leaves, ^"'s- i^o. 



which are long, narrow, and pointed. 



Fig. 130 rejDresents the Ixia (black- 

 berry lilj) ; a is an entire flower ; 1) the 

 corolla cut lengthwise, showing the thi'ee 

 stamens. At c is the flower of the mat- 

 grass {jyardus)^ having but one pistil, and 

 therefore se2)arated from the grass family, 

 the greater part of which we shall meet 

 with in the next order of this class. 



173. Order Digynia^ tioo pistils. — We 

 find here the natural family of the grasses 

 {Graminacece)\ they are distinguished by 

 a straight^ liolloii\ and jointed stem, or cuhii ^ the long and 

 linear leaves are placed at each joint of the stalk, in alternate 

 order, inclosing it like a sheath ; flowers in spikelets formed 

 of an outer enveloj)e of one or two bracts, called glumes^ and 

 an inner envelope (corolla) of two bracts, called jpalece^ which 

 constitute the chaff of oats, rye, (fee. 



a. These little flowers are best observed in a mature stage of the plant when, then 

 bracts being expanded, three filaments appear, containing each a large double 

 anther ; the txm pistils have a reflexed, feathered stigma. They have no seed- 

 vessel ; each seed is contained within the bracts, which gradually open, and unless 

 the seed is gathered in season it falls to the ground. This facility for the distribu- 

 tion of the seed is one cause of the very general diffusion of grasses. The roots of 

 grasses are fibrous, and increase in proportion as the leaves are trodden down, or 

 consumed ; and the stalks which support the flower are seldom eaten by cattle, so 

 that the seeds are suffered to ripen. Some grasses which grow on very high 

 mountains, where the heat is not sufficient to ripen the seed, are propagated by 

 suckers, or shoots, which rise from the root, spread along the ground, and then take 

 root ; such grasses are called stolonlferous. Others are propagated in a manner 

 not less wonderful ; for the seeds begin to grow while in the flower itself, and 

 new plants are there formed, with little leaves and roots ; they then fall to the 

 ground, where they take root. Such grasses are called viviparous, which signifies 

 producing their offspring alive, either by bulbs instead of seeds, or by seeds 

 germinating on the plant. The seeds of the grasses have but one lobe^ or are 

 not naturally divided into parts like the apple-seed and the bean ; therefore these 

 are said to be monocotyledonous. The stems of gramineous plants, like those of all 

 the monocotyledons, are endogenous. With regard to the duration of the grass- 

 like plants, some are annual ; as wheat, rye, and oats, whose roots die after the 

 grain or seed is matured. The meadow grasses are perennial ; their herbage dying 

 in autumn, and the roots sending out new leaves in the spring. 



174. The family of grasses is one of the most natural of all the vegetable tribes: 

 the plants which compose it seem at the first glance to be so similar that it would 

 appear impossible to separate them into species, much less into genera ; but scien- 

 tific research presents us with differences sufticicut to form a basis for the estab- 

 lishment of a great number of genera. These genera are chiefly distinguished by 

 the different form of the corollas and the shape of the leaves. The essential charac- 

 ter of the oat consists in the jointed, twisted awn or beard, which grows from the 

 back of the blossom ; the oat is also remarkable for its graceful panicle. The rye 



173. Describe the grass family — a. Filaments — Pistils — Roots of grasses— Manner in which grasses 

 are propagated— Seeds— How do the stems of the grasses grow ?— Duration of gra.*s-like plants. — 

 171. What is remarked of the 6ei)aration of the grasses into genera and species ?— How are Uie genera 

 <li=Mngui8hed J 



