BULBS AND BULBLETS. 



109 



191. A Bulb is a permanently abbreviated stem, mostly shorter 

 than broad, and clothed with scales, which are imperfect and thick- 

 ened leaves, or more commonly the thickened and persistent bases 

 of ordinary leaves (Fig. 176). In other words, it is a scaly and 

 usually subterranean bud, with thickened scales, and a depressed 

 axis which never elongates. Its centre or apex develops upward 

 the herbaceous stalk, foliage, and flowei-s of the season, and beneath 

 emits roots. In the bulb, the thickening by the deposition of nutri- 

 tive matter, stored for future use, takes place in the leaves or scales 

 it bears, instead of the stem itself, as in the preceding forms. The 

 scales are sometimes separate, thick, and narrow, as in the Scaly 

 bulb of the Lily (Fig. 172) ; sometimes broad and in concentric 

 layers, as in the Tumcated bulb of the Onion (Fig. 177). 



192. BulbletS are small aerial bulbs, or buds with fleshy scales, 

 which arise in the axils of the leaves of several plants, such as the 

 common Lilium bulbiferum of the gardens (Fig. 174), and at length 

 separate sjiontaneously, falling to the ground, where they strike root, 

 and grow as independent plants. In the Onion, and other species of 

 Allium, bulblets are often produced in place of flower-buds. These 

 plainly show the identity of bulbs Avith buds. 



193. All these extraordinary, no less than the ordinary, forms 



FTG. 177. Section of a tunicated bulb of the Onion. 



FIG. 178. Vertical section of the bulb of the Tulip, showing its stem (a) and buds (fr, c). 

 FIG. 179. Bulb of a Garlic, with a crop of young bulbs. 

 FIG. 180. Vertical section of the corm of Crocus : a, new buds. 



FIG. 181. Vertical section of the corm of Colchicum, with the withered corm of the pre- 

 ceding (a), and the forming one (c) for the ensuing year. 



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