VEGETATIVE REPRODUCTION 
113 
It is well-known that in a sense the vegetative and ‘true’ 
reproductive activities of a plant are antagonistic (see p. 103). 
If a plant is growing in rich soil or in the shade, the vege- 
tative activity is favoured, whereas when vegetative growth 
is checked, the plant tends to flower more. Excessive 
vegetative activity tends to favour vegetative reproduction 
at the expense of sexual. Vochting has shown by experi- 
ment that reduced light favours vegetative multiplication. 
It is rare for the root to give rise to a shoot ; vegetative 
reproduction generally consists in the detachment of a shoot- 
structure, with or without roots. It is almost confined to 
herbaceous plants ; few trees are thus propagated. 
The simple detachment of a branch, not in any way modified in 
structure, is common in water-plants, and in plants with rhizomes. 
Special branches for vegetative propagation are the runners of Fragaria, 
Ranunculus, Agropyron, Ajuga, Nephrolepis, &c., the suckers of 
Gesneriaceae, Epilobium, Rubus, Agave, Sempervivum, Salicaceae, &c. 
Bulbs, corms, tubers, &c. (Chap. III.) all lend themselves readily to 
this mode of propagation. Similar structures appear above ground in 
many plants, and are then primarily reproductive ; such are the bulbils 
or little bulbs of Lycopodium, Agave, Lilium, Allium, Remusatia, 
Gagea, Oxalis, &c., which usually appear in place of flowers, in the 
inflorescence, the tubers of Begonia, Globba, Polygonum, &c., the 
young plants that appear by budding of tissues in Asplenium, Cardamine, 
Bertolonia, Begonia, Rubus, Chlorophytum, Crassula, &c. 
The disadvantage in vegetative multiplication is that the offspring 
shall be so closely crowded together as to cause a severe competition 
between themselves and between them and the parent. To avoid this 
danger there are several methods, as seen in seed-reproduction. In 
water-plants the detached branches or buds are carried away by the water. 
Many detached parts are carried off by birds for nest-making, e.g. in Til- 
landsia usneoides ; others can adhere to animals, e.g. the hooked bulbils 
of Remusatia, the branches of Mammillaria, &c. The nodes of Panicum 
and other grasses pass through the alimentary canals of animals and 
subsequently germinate. The tubers of Senecio articulala may be rolled 
along the ground by the wind, like the plants of Selaginella lepidophylla. 
The bulbils so frequent in inflorescences may be jerked away when the 
plant is shaken. In reproduction by suckers, runners, or similar methods, 
the length of these is usually sufficient to ensure separation. 
Appendix. Hairs, Emergences, Latex, &c. A 
few minor anatomical features remain to be mentioned, as 
they are of importance in classification, natural history, &c. 
Hairs are cellular outgrowths from the epidermal tissue, branched 
or unbranched, of the most various shapes, and are exceedingly common 
on all parts of plants (for descriptive terms see p. 53). Their use is 
8 
W. 
