374 
PLANT STUDIES 
leaves expanded to the air and sunlight, the plantlet has 
become independent (Fig. 331). 
It must not be supposed that all of the details just 
given apply to the germination of all seeds, for there are 
certain notable variations. For ex- 
ample, in the pea and acorn the 
cotyledons, so gorged with food as 
to have lost all power of acting as 
leaves, are never extricated from 
the seed-coats, but the stem tip, 
which lies between the cotyledons, 
is pushed out by the elongation of 
the cotyledons at base into short or 
sometimes long stalks. In the ce- 
reals, as corn, wheat, etc., the em- 
bryo lies close against one side of 
the seed, so that it is completely 
exposed by the splitting of the thin 
skin which covers it. In such a 
case the cotyledon is never un- 
folded, but remains as an absorbing 
organ, while the root extends in 
one direction, and the stem, with 
its succession of unsheathing leaves, 
develops in the other. 
248. Summary from Angiosperms. 
At the beginning of this chapter 
FIG. 331. seedling of hornbeam ( 237) the characters of the Gym- 
(Carpinus), showing pri- nos p e rms were summarized which 
mary root (Jiw) bearing root- * . . 
lets (gw) upon which are distinguished them irom Angio- 
numerous root hairs (r), h y - S p e rms, whose contrasting charac- 
pocotyl (h), cotyledons (c), , , ,, 
young stem (>, and tot (/> ters may be stated as follows : 
and second (f) true leaves. (1) The Hlicrospore (pollen- 
-After SCHIMPEB. grain), chiefly by insect pollination, 
is brought into contact with the stigma, which is a recep- 
tive region on the surface of the carpel, and there de- 
