40 



HOW PLANTS GROW. 



rests on the soil ; as in the Houseleek (Fig. Go), where one plant will soon produce 



a 'cluster of 3oiing plants or offsets all around it. 



103. A rkOOislock is any kind of horizontal stem or branch growing under ground. 



Slender rootstocks occur in the subterranean part of the suckers of Roses, of Pepper- 

 mint, or of Canada Thistle, and of Quick-Grass or Couch-Grass 

 (Fig. 75), which spreads so widely, and becomes so troublesome 

 to farmers. They are well distinguished from roots by the 

 leaves which they bear at every joint, in the form of scales, and 

 by the buds which they produce, one in the axil of each scale. 

 These buds, which are very tenacious of life, are what renders 

 the plant so exceedingly difficult to destroy. For ploughing and 

 hoeing only cut up the rootstock into pieces, each with a tuft of 

 roots ready formed and with a bud to each joint, all tlie more 

 ready to grow for the division. So that the attempt to destroy 



Quick- Grass by cut- 



ting it up by the 

 roots (as these shoots 

 are called), unless the 

 pieces are carefully 





U 



Koolstuck of Q,ijick-;^rnss. 



taken out of the roil, is apt to produce many active plants in place of one. 



104. Thickened or fleshy rootstocks, such as tho^e of Solomon's Seal (Fig. Go) 

 Rnd Iris (Fig. G4), have already been illustrated (70). 



105. A Tuber is a rootstock thickened at the end, as already explained in the 

 Potato and Ground Artichoke (74, 75, Fig. 50, CO). The eyes of a tuber are lively 

 buds, well supplied with nourishment for their growth. 



106. A Corm or Solid Bulb, as of Gladiolus and Crocus 

 (Fig. 70), is a sort of rounded tuber. If well covered with 

 thick scales it v/ould become 



107. A Bulb. This is a (mostly subterranean) stem, so 

 short as to be only a flat plate, producing roots from its lower 

 surface and above covered with thickened scales, — as was 

 lully explained in the last section (77). 



108. Bulbs are scal^j, as in the Lily (Fig. GG), when the 

 scales are narrow ; or coated, as an onion, vvdien the scales enwrap each other, and 

 form coats. 



Corm of Ciotus, wUli bud*. 



