THE VEGETATIVE ORGANS OF PLANTS. 261 
manent, while in others it shortly falls to the ground and 
grows thereafter horizontally. 
All plants of the higher orders have stems, though in 
many instances they do not appear above ground, but ex- 
tend beneath the surface of the soil, and are sage con- 
sidered to be roots. 
While the root, save in exceptional cases, does not de- 
velop other organs, it is the special function of the stem 
to bear the leaves, flowers, and seed, of the plant, and even 
in cértain tribes of vegetation, like the cacti, which have 
no leaves, it performs the offices of these organs. In gen- 
eral, the functions of the stem are subordinate to those 
of the organs which it bears—the leaves and flowers. It 
is the support of these organs, and only extends in length 
or thickness with the apparent purpose of sustaining them 
either mechanically or nutritively. 
Buds,—In the seed the stem exists in a rudimentary 
state, associated with undeveloped leaves, forming a bud. 
The stem always proceeds at first from a bud, during all 
its growth i isterminated by a bud at every growing point, 
and only Geases to be thus tipped when it fully accom- 
plishes its growth by the production of seed, or dies from 
injury or disease. 
In the leaf-bud 
we find a number 
of embryo leaves 
and leaf-like scales, 
in close contact and 
within each other, 
but all attached at 
the base, to a cen- 
tral conical axis, 
fig. 45. The open- 
ing of the bud con- 
sists in the lengthening of this axis, which is the stain: 
and the consequent separation of the leaves from each 
4 
Fig. 45. 
