Also bears tubers; the D, Spore showing the two spiral vegetative shoots have bands of the perinium.
6), the tubers being partly radical partly budlike in their character.
The tubers of Ipomaea Batatas are rich in starch and sugar, and, as the "sweet potato," form one of the most widely distributed foods in the warmer parts of the earth.
All plant life has a remarkably large proportion of subterranean growth, because of the necessity of getting moisture from the earth and not from the air; hence roots and tubers are unusually well developed.
It should be remembered that a single complete defoliation of a herbaceous annual may so incapacitate the assimilation that no stores are available for seeds, tubers, &c., for another year, or at most so little that feeble plants only come up. In the case of a tree matters run somewhat differently; most large trees in full foliage have far more assimilatory surface than is immediately necessary, and if the injury is confined to a single year it may be a small event in the life of the tree, but if repeated the cambium, bud-stores and fruiting may all suffer.