34 



THE STEM, OR ASCENDING AXIS. 



many plants the axis of the primary bud does not develop into internodes at all, or 

 but partially in various degrees, as in the Trillium, Crocus, blood-root. Such stems 

 seldom appear above ground, and are said to be subterranean. 



165. This fact makes a wide difference in the forms of stems, and naturally con- 

 stitutes them into two great divisions, viz., the leaf-stem and the scale-stem. 



166. THE LEAF-STEMS are those forms which, with internodes fully 

 developed, arise into the air crowned with leaves. The principal forms 

 are the caulis, culm, trunk, caudex, vine. 



167. THE SCALE-STEMS arc those forms which, with internodes par- 

 tially or not at all developed, and generally bearing scales, which are 

 undeveloped leaves, scarcely emerge from beneath the soil. They are 

 the creeper and rhizoma (developed), the crown, tuber, conn and bulb 

 (undeveloped). 



42. Scale-stem, (Dicentra cuenllaria). 43, A flower of the same. 44, A flower of D. Canadensls. 

 45, Leaf-stem (Chimapbila inaculata). 



168. THE LEAF-STEMS ARE EITHER HERBACEOUS OR WOODY. The 

 herbaceous, whether arising from annual, biennial or perennial roots, 

 bear fruit but one season and then perish at least down to the root, 

 scarcely becoming woody ; as the (D mustard, radish, and the ij- 

 grasses. The woody leaf-stems survive the winter, and become firm 

 and solid in texture in after years. 



169. CAULIS is a term generally applied to the annual leaf-stems of 



