70 THE STEM. 



duciiig stems which, above the gi-ound, are of annual duration 

 only, and do not become woody. Ex. the grasses, mullein. 



165. The most distinctive property of the stem is the forma- 

 tion and development of buds. At the commencement of its 

 growth, the ascending axis is itself a bud. 



166. Buds are of two kinds, namely, the leaf -hud, containing 

 the rudiments of a leafy branch, and the Jloiver-bud, containing 

 the same elements transformed into the organs of a flower, for 

 the purposes of reproduction. 



• 167. The leaf-bud consists of a minute, tender, growing point 

 of cellular tissue, originating \vith the pith, surrounded and pro- 

 tected by a covering of imbricated scales and incipient leaves. 

 (Fig. 22; 1.) 



1 68. These scaly envelopes of the bud appear to be the rudimentary leaves of 

 the preceding year, formed late in the season, arrested in their development by 

 the frosts and scanty nutriment, and reduced to a sear and hardened state. If 

 the bud of the maple or horse-chestnut (^sculus) be examined, when swollen in 

 spring, the student will notice a gradual transition from the outer sca/cs to the 

 evident leaves within. 



a. It is an interesting illustration of designing "Wisdom, that buds are furnished 

 with scales only in wintry climates. In the ton-id zone, or in hot-houses, where 

 the temperatiirc is equalized through the year, plants develope then" buds into 

 foliage immediately after their fonnation, without clothing them in scales. In 

 annual plants, also, the buds are destitute of scales, not being destined to survive 

 the winter. Hence it is evident that the transformation of autumnal leaves into 

 scales, is a means ordained by the great Author of nature, to protect the young 

 shoots, in their incipient stages, from cold and moisture, — an office which they 

 effectually fulfil by theh- numerous do-wiiy folds, and their insoluble coat of 

 resin. * 



169. The original bud (plumule) of the embiyo is at first 

 developed into a simple stem, and being itself continually repro- 

 duced, is always borne at the termination of that stem ; that is, 

 the axis is always ter^ninated by a hud. 



a. Besides this, the axis produces a bud (21, a) in the axil of each leaf, that is, 

 at the point just above the origin of the leaf-stalk. If these axillary buds remain 

 inactive, the stem will still be simple^ as in the mullein. In general, however, 



* In many trees the scales of the buds are clothed with a thick down. In*'others, as in the 

 horse-chestnut, balm of Gilead, and other species of poplar, the buds are covered with a 

 viscid and aromatic resin, resembling a coat of varnish. A considerable quantity may be 

 separated from a handful of such buds in boiling water. 



