LESSON 0.] 



srnTF.RRANKAN FOKMS : BULBS. 



45 



are usually upright, produciuj^ liuds on tlicir upper purfare and 



roots from the lower, liut (as we see in the Croeus liere (ifrured) 



buds may shoot from just above any of the faint cross lines or 



rings, which are the scars left by the death 



and decay of the sheathing bases of former 



leaves. Tiiat is, these are axillary buds. In 



these extraordinary (just as in ordinary) stems, 



the buds are either axillary or terminal. The 



whole mode of growth is just the same, only 



the corm does not increase in length faster 



than it does in thickness. After a few years 



some of the buds grow into new corms at the 



expense of the old one ; the young ones taking 



the nourishment from the parent, and storing 



up a large part of it in their own tissue. 



Wiien exhausted in this way, as well as by 



flowering, the old corm dies, and its shrivelled 



and decaying remains may be found at the side of or beneath the 



present generation, as Ave see in the Crocus (Fig. 71). 



107. The corm of a Crocus is commonly covered with a thin and 

 dry, scaly or fibrou:^ husk, consisting of the dead remains of the bases 

 of former leaves. "When this husk consists of many scales, there is 

 scarcely any distinction left between the corm and 



108. The Bnlb. This is an extremely short subterranean stem, 

 usually much broader than high, producing roots from underneath, 

 and covered with leaves or the bases of leaves, in the form of thick- 

 ened scales. It is, therefore, the same -as a corm, or solid bulh, only 

 it bears an abundance of leaves or scales, which make up tiic greater 

 part of its bulk. Or we may regard it as a bud, witli thick and 

 flt!shy scales. Compare a Lily-bulb (Fig. 73) with the strong scaly 

 buds of the Hickory and Ilorsechestnut (Fig. 4.S and 40), and tho 

 resemblance will be apparent enough. 



10'.). Bulbs serve the same purpose as tubers, rootstocks, or corms. 

 The main difference is, that in these the store of food for future 

 growth is deposited in the stem ; while in the bulb, the greater part 

 is deposited in the bases of the h-aves, changing them into thick 

 scales, which closely overlap or em-lose one another, because the 

 6tem docs not elongate enough to separate them. That the scales 



Fit;. 71. Curiii ot M<Uii tMilb of a Cnx-ii 



7'i. 'I'lio k.-iiiio, cut lliroiicli U>ii;;(liwis«. 



