THE GRASS FAMILY 387 
are called exogenous 1 or outside-growing, because new wood 
when formed is added on the outside of an older ring. 
143. The grass family (Gramine). Examples: oat (Fig. 1- 
4, pages 12-14), rice (Figs. 5, 6, pages 16, 17), rye (Fig. 
7, page 18), wheat (Figs. 8, 9, pages 19, 20), barleys (Figs. 
10-12, pages 21, 22), maize (Figs. 13-15, pages 23, 24), 
sugar-cane (Fig. 114, page 106), broom-corn (Fig. 222, page 
236), and bamboo (Fig. 224, page 239). 
Formulas of Zea, Saccharmum, Andropogon, Oryza, Avena, 
Secale, Triticum, Hordeum, Bambusa, and Graminee are shown 
on pages 420-423. 
The grasses introduce us to a new sub-class, characterized 
partly, as we shall see, by having the leaf-veins running in a 
regular, more or less parallel system. Leaves with such a 
framework are said to be parallel-veined. Grass leaves always 
have the veins running lengthwise from base to tip. 
Other noteworthy features of grass leaves are that the base 
is wrapped about the stem so as to form a sheath the edges 
of which overlap as shown in Fig. 13; and the blades extend 
from only two sides of the stem, thus coming into two vertical 
ranks. 
Most grass stems are round and hollow like straws. Rarely, 
as in the stalk of maize, there is a solid cylinder of pith, 
through which run scattered bundles of firmer, more or less 
woody material, not forming true rings, but often so crowded 
toward the surface as to constitute a somewhat bark-like 
zone. From an erroneous idea that these scattered bundles 
originated near the center of the stem and were forced out- 
ward by new growth, all stems with scattered bundles were 
early described as “‘inside-growing”’ or endogenous —a term 
still used conveniently, however, by way of contrast for stems 
of seed-plants of the non-exogenous type. 
The bracts and bractlets of grasses in general are com- 
paratively thin and stiff, like the husks or chaff of grain, 
and have received the special name of glumes.* 
1 Bx-og’en-ous < Gr. exo, outside; genes, seadavitvag: 
2 En-dog’en-ous < Gr. endos, within. 
3 Glume <_ L. gluma, husk of corn. In our formulas the glumaceous 
character is denoted by the inverted exclamation mark as in Bj. 
