130 A TEXT-BOOK OF GRASSES 
protection, germination or dispersal. In the present discussion the 
term fruit is used in both senses. 
The fruit of Panicum and allied genera consists of 
the hard, tightly closed fertile lemma and palea within 
which is the caryopsis (Fig. 21). Not infrequently the awn 
of the lemma is involved in the fruit and performs an 
important function in dispersal or in connection with 
germination. This is the case with Stipa (Fig. 36), 
Aristida (Fig. 35), Heteropogen and many Avenez. 
The fruit may include the surrounding sterile branchlets 
forming a bur, as in Cenchrus (Fig. 27); a greatly har- 
dened inclosing bract, as in Coix (Fig. 12); the joints of 
the rachis in which the spikelet is partially inclosed, as in 
Tripsacum; or a combination of rachis joint and long- 
awned sterile spikelets, as in Sitanion and Hordeum. 
Rarely the ovary ripens into some form other than a 
caryopsis. In a few genera such as Sporobolus and EHleu- 
sine, it becomes an utricle, the pericarp being thin and not 
grown to the seed. In many species of Sporobolus, for 
example S. airoides Torr. and S. indicus (L.) R. Br., the 
pericarp tends to split vertically into 2 valves, thus being 
dehiscent. The pericarp of Eleusine breaks away irregu- 
larly. The fruit becomes a nut or a berry in certain 
bamboos. 
163. The seed consists of an embryo at the base on 
one side and of endosperm occupying the remaining por- 
tion. If the surface of a caryopsis is examined, the posi- 
tion of the embryo is outlined as a depressed usually oval 
area at the base on the front side, that is, on the side 
facing the lemma. On the opposite side, next the palea, 
is the mark called the hilum, which indicates the place 
where the seed was attached to the wall of the ovary 
(pericarp). The hilum may be elongated if the seed is 
