58 



THE STEM 



Bulbletsof the Tiger Lily. 



as this perhaps represent the first step in the process of 

 change by which the ancestors of our Bellwort (Fig. 20) 

 and Blooclroot (Fig. 25) became subterranean in habit. 



86. Stems for propagation ; that is, for the establish- 

 ment of new individual plants. Many plants reproduce 

 their kind without the intervention of seed. Some part 

 of the original plant is separated from the parent stock 

 and develops into a new plant. This is termed vegetative 

 reproduction, to distinguish it from reproduction by seed. 

 The Potato is regularly propagated by this method, as 

 also in the tropics are Sugar Cane, the Banana, and the 

 Pineapple, none of wdiich ordinarily produce seed. 



87. A carious mode of vegetative 

 reproduction is by the bulblets, or small 

 bulbs, formed in the axils of the leaves 

 of certain garden Lilies (Fig. 43), and 

 often in the flower clusters of the Onion. 

 They are plainly buds with thickened 

 scales. They never grow into branches, 



but detach themselves when full grown, fall to the ground, and take 



root there to form new plants. 



88. A stolon is a branch from above ground, which reclines or 

 becomes prostrate and strikes root (usually from the nodes) wherever 

 it rests on the soil. Thence it may send up a vigorous shoot, which 

 has roots of its own, and becomes an 



independent plant when the connecting 

 part dies, as it does after a while. 



89. An offset is a short stolon, or 

 sucker, with a crown of leaves at the end, 

 as in the Houseleek (Fig. 4-4), which 

 propagates abundantly in this way. 



90. A runner, of which the Straw- 

 berry presents the most familiar and 

 characteristic example, is a long and 

 slender, tendril-like stolon, or branch from next the ground, destitute 

 of conspicuous leaves. Each runner of the Strawberry, after having 

 grown to its full length, strikes root from the tip becoming fixed 

 to the ground, then forms a bud there, which develops into a tuft of 

 leaves, and so gives I'ise to a new plant, which sends out new runners 

 to act in the same way. In this manner a single Strawberry plant 

 will spread over a large space, or produce a great number of plants, 

 in the course of the summer, all connected at first by the slender 



■i-i. Houseleek, propagating 

 by offsets. 



