VEGETATIVE REPRODUCTION 161 
extreme cold, and the food destined for them goes into 
the little plants instead. 
7. Multiplication by Detached Shoots—e.g., some aqua- 
tics (see p. 53). 
It is clear from this that the vegetative mode of repro- 
duction in all its various forms is really one of bud- 
detachment. Bulbs, corms, and bulbils are obviously 
only buds rich in food-reserves. 
Cuttings, fragments of rhizomes, 
runners, suckers, and tubers are 
modified bud-bearing shoots. In 
viviparous roots and leaves buds 
arise on organs which normally do 
not bear them. It seems, indeed, 
as if any part of a plant, which con- 
tains soft tissue capable of growth, 
may produce buds if a sufficient 
stimulus is present. One condi- 
tion is always necessary—abund- 
ance of food at the points where 
the buds are destined to form. 
The stimulus in most cases is pro- 
vided by some check taking place 
in the ordinary processes of growth, 
and a transference of vegetative 
activity to new centres — the 
brood-buds. The bud is, there- 
fore, the basis of vegetative multi- INS 
plication in the higher plants, and jyg. 65. — Poa alpina. 
its success is due to— SHOWING REPLACEMENT 
1. The reserve - food stored 0 Fuownrssy Vivirar- 
5 ; : ouUS PLANTLETS. (AFTER 
up in the bud itself or in KEENER.) 
organs closely connected with it. 
2. Its power of developing adventitious roots, with- 
out which independent life would be impossible. 
3. Its xerophytic nature, enabling it to remain in a 
resting or dormant condition during the periods un- 
. favourable to vegetative growth. 
4. In many cases to the protection secured to it by 
living underground. 
