156 BRITISH PLANTS 



run a few inches along the ground, root, and at their 

 extremity form new plants. Thus, in the autumn, a parent- 

 plant may be seen surrounded by a circle of descendants. 

 When the old plant dies the stolons perish, and the off- 

 spring become independent. Creeping stems : in some 

 prostrate plants the ordinary stems and shoots creep along 

 the ground and root at the nodes. By the dying away of 

 the main stems the branches are liberated as separate 

 plants e.g., ground-ivy, creeping Jenny. 



3. Bulbs and Corms (p. 111). These are compressed 

 shoots or buds, capable of rooting, and, by reason of the 

 food-reserves they contain, capable of independent life. 

 In bulbs the food-material is stored in swollen leaves, the 

 stem being relatively small ; in corms the stem becomes 

 swollen and filled with food, the leaves being reduced to 

 scales which enclose and protect the stem. In both cases 



new plants arise as buds in 

 the axils of leaves on the old 

 bulb or corm, but their de- 

 velopment proceeds along dif- 

 ferent lines in different plants. 

 In the tulip (Fig. 59) the 

 bulb consists of a short axis 

 bearing four or five thick, 

 FIG. 58. - HOUSED, WITH loosely-arranged scale-leaves 

 OFFSETS. which entirely ensheath the 



stem ; these are enclosed by 



a single thin, dry, brown scale, which effectively prevents 

 evaporation of water from the storage-leaves. The centre 

 is occupied by the flowering shoot and'the young foliage- 

 leaves. In the spring, as the flower and leaves grow into 

 the air, the food passes into them, and the fleshy food- 

 scales shrink somewhat. A bud in the axil of the inner- 

 most scale now begins to grow. Surplus food in the 

 scale-leaves, together with food manufactured in the 

 foliage-leaves, pours into it, and the bud gradually assumes 

 the form and proportions of a bulb. By the time this 

 new bulb has completed its development the flower, 

 foliage-leaves, and old scale-leaves have withered. In 

 this way a new bulb is produced each year. In the larger 

 bulbs more than one bud may develop, and in this way 

 multiplication is secured. The production of several 

 buds instead of one is insured by removing the flowering 



