46 



STEMS. 



[SECTION 6. 



That of Indian Turnip is formed one year and is consumed the next. Fig. 

 104 represents it in early summer, having below the corm of last year, from 

 which the roots have fallen. It is partly consumed by the growth of the 



stem for the season, and the 

 corm of the year is forming 

 at base of the stem above 

 the line of roots. 



112. The corm of Crocus 

 (Fig. 105, 106), like that 

 of its relative Gladiolus, is 

 also reproduced annually, 

 the new ones forming upon 

 the summit aud sides of the old. Such a corm is like a tuber in bud- 

 ding from the sides, i. e. from the axils of leaves ; but these leaves, instead 

 of being small scales, are the sheathing bases of fo- 

 liage-leaves which covered the surface. It resem- 

 bles a true bulb in having these sheaths or broad 

 scales ; but in the corm or solid bulb, this soHd part 

 or stem makes up the principal bulk. 



113. The Bulb, strictly so-called, is a stem like 

 a reduced corm as to its solid part (or plate) ; 

 while the main body consists of thickened scales, 

 which are leaves or leaf-bases. These are like bud- 

 scales ; so that in fact a bulb is a bud with fleshy 

 scales on an exceedingly short stem. Compare a 

 White Lily bulb (Fig. 107) with the strong scaly 

 buds of the Hickory and Horse-chestnut (Fig. 72 

 and 73), and the resemblance will appear. In 

 corms, as in tubers and rootstocks, 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 leaves, changing them into tliiclf 

 scales, which closely overlap or enclose one another. 



] 14. A Scaly Bulb (like that of the Lily, Fig. 107, 108) is one in whicli 

 the scales are thick but comparatively narrow. 



115. A Tunicated or Coated Bulb is one in which the scales enwrap 

 each other, forming concentric coats or layers, as in Hyacinth and Onion. 



Fio. 103. Corm of Cyclamen, much reduced in size : roots froin lower^ace, leaf- 

 stalks aud flower-stalks from the upper. 



Fia. 104. Corm of Indian Turnip (Arissema). 



Fig. 105 Corm of a Crocus, the investing sheaths or dead leaf-bases stripped 

 off. The faint cross-lines represent the scars, where the leaves were attached, i. e. 

 the nodes : the spaces between are the intemodes. The exhausted corm of the 

 previous year is underneath ; forming ones for next year on the summit and sides. 



Fig. 106. Section of the same. 



