Ch. XXI.] CLASSES AND ORDERS. 125 
531. Orper 2, Dieynia, two pistils. We here find the 1mpor- 
ant family of orasses, of shite there are many different gene- 
ra. They are distributed throughout the globe, and furnish 
many of the most useful vegetables for man and beast. 
532. Among the most useful of the grass family, are wheat, 
rye, barley, oats, Indian corn, and rice, besides meadow-grass 
and those kinds which are eaten by cattle. — 
533. Indian corn, though it is ranked with the grasses on ac- 
count of its long and linear leaves, its fibrous roots, and some 
other particulars, yet it is not placed in the third class, because 
its stamens and pistils are not in the same flower. Rice is 
placed in the sixth class on account of the number of its sta- 
mens. You see that natural families are sometimes separated 
by the artificial classification ; as in the second class two grass- 
es were mentioned, which were placed there on account of hav- 
ing two stamens. 
534. Grasses have fibrous roots, their stems are of that kind 
called culms, being long, slender, and hollow, and having knots 
from which arises a long linear or lanceolate leaf surrounding 
the stem like a sheath. 
535. The stems of grasses grow internally, or from the centre 
outwards ; this is the reverse of what appears in the oak, the 
new wood of which encircles the old. 
536. The flowers of the grasses are found in what is called 
the ear or head; and consist of a calyx of two green husks 
called a glume ; within this calyx is the blossom, consisting of 
a husk of two pieces; these husks are the chaff, which is sepa- 
rated from the seed by threshing. If you observe a blossom ot 
wheat, or of common meadow grass, you wiil see three sta- 
mens with large anthers, and two pistils with feathered stig- 
mas. 
537. The grasses have no seed vessel, but the seed is con- 
tained within the husks, which gradually open and throw out 
their contents; this scattering of the seed is the cause of the 
very general distribution of grasses. 
538. Wheat, rye, and oats, are annual plants; that 1s, their 
roots die every year, and the plant is renewed by means of the 
631. What important family do we find in the 2d order of the class 
Triandria ? 
532. Which are some of the most useful of the grass family ? 
533. Why are not Indian-corn and Rice classed with the ac 
534. What is said of the roots of grasses ? 
535. What of their stems ? 
536. What of their flowers ? 
537. Have the grasses a seed vessel ? 
538. What erste are annual, and what are perennial ? 
Lae 
