he Beech (Fig. 31-33), except
that the caulicle lengthens less, hardly raising the cotyledons out of
the ground. Nothing would be gained by elevating them, as they never
grow out into efficient leaves; but the joint of stem belonging to the
plumule lengthens well, carrying up its pair of real foliage-leaves.

26. It is nearly the same in the Bean of the Old World (Vicia Faba, here
called Horse Bean and Windsor Bean): the caulicle lengthens very little,
does not undertake to elevate the heavy seed, which is left below or
upon the surface of the soil, the flat but thick cotyledons remaining
in it, and supplying food for the growth of the root below and the
plumule above. In its near relative, the Pea (Fig. 34, 35), this use of
cotyledons for storage only is most completely carried out. For they are
thickened to the utmost, even into hemispheres; the caulicle does not
lengthen at all; merely sends out roots from the lower end, and develops
its strong plumule from the upper, the seed remaining unmoved
underground. That is, in technical language, the germination is
_hypogaeous_.

[Illustration: Fig. 26. Embryo of Pumpkin-seed, partly opened. 27. Young
seedling of same.]

[Illustration: Fig. 28. Embryo of Common Bean (Phaseolus vulgaris):
caulicle bent down over edge of cotyledons. 29. Same germinating:
caulicle well lengthened and root beginning; thick cotyledons partly
spreading; and plumule (pair of leaves) growing between them. 30. Same,
older, with plumule developed into internode and pair of leaves.]

27. There is sufficient nourishment in the cotyledons of a pea to make a
very considerable growth before any actual foliage is required. So it is
the stem-portion of the plumule which is at first conspicuous and
strong-growing. Here, as seen in Fig. 35, its lower nodes bear each a
useless leaf-scale instead of an efficient leaf, and only the later ones
bear leaves fitted for foliage.

[Illustration: Fig. 31. A Beech-nut, cut across. 32. Beginning
germination of the Beech, showing the plumule growing before the
cotyledons have opened or the root has scarcely formed. 33. The same, a
little later, with the plumule-leaves developing, and elevated on a long
internode.]

[Illustration: Fig. 34. Embryo of Pea, i. e. a pea with the coats
removed; the short and thick caulicle presented to view. 35. Same in
advanced germination: the plumule has developed four or five internodes,
bearing single leaves; but the first and second