eg LECTURE V. 



developed from various places on the shoot-axes, or even from leaves, and which 

 cannot be looked upon as metamorphosed shoots or leaves. In the Roses and 

 Brambles they are known to everyone; among the American species of Solamm, 

 many are remarkable for conspicuous brightly coloured prickles, e.g. Solanum pyra- 

 cantha and atro-sanguineum ; many Palms, on the other hand, have very long and 

 hard ones resembling those of a porcupine. 



Among sub-aerial shoots the filiform, often very long runners, which usually 

 spring from the base of an upright leafy shoot and bear a few inconspicuous 

 leaf-scales on their long internodeS, deserve even if only passing mention here. 



FIG. 53.— A potato plant grown from seed, r primary root; f ^cotyledons ;yy foliage leaves; £( lateral shoots, 

 with leaf scales d d \ th the tubers at the ends of these shoots (after Duchatre). 



These produce, at some distance from the mother-plant, a rosette of foliage leaves, 

 from which spring, downwards, a tuft of roots, and upwards, flower shoots, 

 The Strawberry affords a very good example. Runners of this kind are funda- 

 mentally organs of multiplication, since from each rooted tuft of foliage leaves at 

 the end of a runner, the filiform part of which perishes later, a new independent 

 plant arises. Very many other plants behave in a similar manner; their runners 

 or stolons grow forth as horizontal fibres beneath the surface of the earth, and 

 produce from their terminal bud a new rooted plant, often far removed from the 

 mother-plant. This is the case for example in the Umbellifer uEgopodium poda- 

 grarta, in the common Valerian {Valeriana officinalis), and in many labiate plants 



