8 | - ELEMENTARY BOTANY 
Comparing the germination of sunflower with that of bean, 
there is this difference to note: the two cotyledons do not remain 
Fics. 10 anD 11.—SUNFLOWER. 
pr, wall of seed-vessel; 2, attach- 
ment of parts of flowér; 7, radicle 
c, cotyledons ; m, micropyle ; 7h, root- 
hairs. 

in the ground as they do 
in the bean, but are borne 
upwards by the growth in 
length of the stem beneath 
the cotyledons, generally 
carrying the seed- vessel 
with them. This soon 
falls off; the cotyledons 
then expose their inner 
surfaces to the sunhght, 
turn green, and begin to 
make food for the seedling. 
The plumule emerges 
from between the cotyle- 
dons, and grows into the 
shoot. 
The portion of the stem 
beneath the cotyledons is . 
called the hypocotyle- 
donary stem (Gk. hypo= 
under). 
COMPARISON OF GERMINATION. 
BEAN. 
1. A seed. 
2. The brown skin is the seed 
coat. 
{ radicte. 
plumule. 
liwo cotyledons. 
4. Cotyledons remain in the 
ground, and do not turn 
green. 
5. One main root with lateral 
branches. 
38. Embryo 
SUNFLOWER. 
A seed + seed-vessel, the brown _ 
shell being wall of seed- — 
vessel. 
The seed coat isthe thin, white 
skin within the brown 
shell. 
radicle. 
Embryo; plumule. 
two cotyledons. 
Cotyledonscomeabove ground 
and turn green. 
One main root with lateral 
branches. 
