31 
Sheath. The short axis terminates in a single radicle. Among the 
peculiarities noticed in this tribe is the genus Stipa. Stipa pennata has 
a well-marked epiblast more than half the length of the plumule, while 
S. tenacissima (figs. 30 and 31, Pl. IV) has a very small epiblast. In 
fig. 31 the opening of the plumule-sheath is apparent. In Stipa richard- 
sont (figs. 36 and 37 A and B, PI. V) the epiblast extends more than 
half the length of the plumule, and the radicle is directed obliquely 
outward. Although S. viridula (figs. 32 and 33, Pl. IV) has a very 
small fruit, yet its embryo has proportionately the largest epiblast. 
Eriocoma cuspidata (figs. 34 and 35, Pl. IV).—The fruit of Eriocoma 
resembles that of Oryzopsis, but has a very large epiblast which extends 
the whole length of the plumule. The scutellum differs from Oryzopsis 
in having a groove at its base. This character, together with the long, 
densely hairy, flowering glumes, would warrant its being placed as a 
separate genus Hriocoma, which is regarded as a subgenus by Hackel. 
Oryzopsis micrantha (figs. 38 A and B, Pl. V), Phleum pratense (fig. 
41, Pl. V), Cinna arundinacea (figs. 39 and 40, Pl. V), and Brachyely- 
trum erectum (fig. 43, Pl. V) all have a well-marked epiblast. The last 
named ean easily be recognized by a long, pointed projection proceeding 
from the pericarp. This projection contains no starch, and its presence 
is remarkable from the fact that it is the only fruit in which such a 
structure has been found. Ammophila arenaria (fig. 42, Pl. V) presents 
a peculiar appearance. Its cotyledonary sheath extends down to the 
apex of the plumule. The seutellum also branches into three in the 
upper part. 
Tribe AVENE. 
The Avene resemble the Hordec in the structure of fruits. The 
embryo is usually small compared with the amount of endosperm. 
Lateral roots oceur in Avena. The scutellum-bundle is inserted at the 
base of the plumule and continues down into the axis in the form of a 
loop. 
doen sativa (figs. 44, 45, 46 A-B, 47 A-G, 48, Pls. V and VI)—Fig. 
47 A-G, Pl. V, represents a series of transverse sections through the 
embryo from the plumule to the radicles. At A one sees the peculiar 
shape of the scutellum, with its vascular bundle, while within is the 
plumule-sheath, with its bundles, inclosing the first true leaf. B repre- 
sents a section taken somewhat lower down in the plumule and shows 
the position of the second leaf directly opposed to the first. The scu- 
tellum-bundle branches at the base of the plumule, as may be seen at 
C, to form the bundles of the plumule-sheath. Part of the plumule- 
sheath is still present, while within is the axis with the first leaf and 
its bundles just beginning to differentiate. Figs. D, E, and F show 
the axis, and the epiblast which becomes larger toward the base. At 
E only one radicle is present while at F there are three. G shows the 
position of the four radicles. The main radicle is in the center with 
one on each side to the right and left, and a fourth smaller one in front. 
