Vill] FRUITS OF GRASSES 123 
Thirdly, the outermost layer or layers of cells of the 
endosperm are filled with proteids, and are known as 
the Aleurone layer. (Fig. 38, A.) 
The embryo consists of the folded embryonic leaves in 
bud (plumule) above, which will grow up on germination 
as the shoot or “spear,” the short primary root (radicle) 
below, with in many cases two or more secondary rootlets 
already showing in its tissues, and 
from the common “collar” uniting 
these a more or less prominent 
‘shield-shaped organ (scutellum) 
standing out laterally in contact 
with the endosperm, the dissolved 
contents of which it absorbs on 
gerinination. (Fig. 38, s.) 
Although typical grasses form a 
caryopsis as described, exceptions 
occur. In the exotic Sporobolus, 
Hleusine, Crypsis and Heleochloa the 
Fig. 40. Triodia decum- 
bens. a, ‘‘seed,” nat, 
seed being loose in the fruit, and the size; b, ditto, x 6. 
Note the basal hair- 
; : tuft and rachilla, and 
and in many Bamboos the seed is fe ciliate, foothed 
loose in the achene, while in a few _— outer palea with a 
short awn-point, en- 
closing the inner more 
fleshy and may be as big as a delicate palea. Be- 
tween the two lies the 
caryopsis. Nobbe. 
fruit becomes truly dehiscent, the 
latter opens and allows it to fall out ; 
cases—e.g. Melocanna—the fruit is 
walnut. 
Returning to the typical grasses. 
When the fruit ripens in the spikelet, several events may 
happen. 
