Ch. IV, 10] 



FOLIAGE-BEARING STEMS 



189 



Some plants develop both upright and reclined stems, the 

 latter, called stolons, lying close to the ground, as in 

 Hobble-bushes/ descriptively named. Short leafy stolons, 

 called offsets, are formed by some plants of compact 

 growth like the Sempervivums, which thereby spread out- 

 ward in a continuous 

 growing mat (Fig. 

 131). Very long and 

 slender stolons, evi- 

 dently adapted to 

 spreading the plant, 

 are called runners, 

 as familiar in the 

 Strawberry. 



The flowering 

 plants are typically 

 land dwellers, but in 

 course of their evolu- 

 tion some kinds have 

 returned to a life in 

 the water, — e.g. 

 Water-lilies and a 

 great many of the 

 Waterweeds. The 

 stems of such plants 

 are buoyed up by 

 the water, which 

 thus supplies the 

 support for the foli- 

 age, in correspond- 

 ence wherewith the stems are weak and soft, serving rather 

 as cords to retain the leaves than columns to lift them. 



Some flowering plants live also in deserts, into which they 

 have been forced in the course of evolution. The scarcity 

 of water entails on such plants great reduction of surface, 

 leading in the most typical cases, like the Cactus, to aban- 



Fig. 132. — Fucus vesiculosus, the common 

 brown Rockweed ; X {. (From Figurier.) 



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