GENERAL MORPHOLOGY OF THE PLANT 51 



branous scales or cataphyllary leaves. It differs from the bulb 

 by the stem becoming large and fleshy, and the scales being 

 reduced to thin membranes. The corm shows itself to be a 

 kind of stem by producing from its surface one or more buds, in 

 the form of young corms, as in the Crocus (fig. 75, a, V), where 

 they proceed from the apex, o, and ultimately destroy their 

 parent by feeding upon its accumulated nutriment. These new 

 corms, in a future year, also produce others near their apex, 

 and these by developing at the expense of their parents also 

 destroy them in like manner, and these again form other corms 

 by which they are themselves destroyed. In this manner the 

 new corms, as they are successively developed from the apex of 

 the old corms, come gradually nearer and nearer to the surface 

 of the earth. 



In the Colchicum (fig. 77), the new corm a'" is developed 

 on one side of the old corm near its base, instead of from the 

 apex, as in the Crocus. This also feeds upon its parent, and 

 ultimately destroys it, and is in like manner destroyed the next 

 year by its own progeny. Thus, in taking up such a corm 

 carefully, we find (fig. 77), a, the shrivelled corm of last year ; 

 and a", that of the present season, which, if cut vertically, 

 shows a'", the corm in a young condition for the next year. 



Another type of the corm is found in the Cj'clamen. It is a 

 fleshy expansion of the base of the seedling stem which thickens 

 and enlarges year by year, but does not lengthen, thus becoming 

 a broad thick body. The thickening is confined to the first 

 internode. It bears annually leaves and flowers from its 

 apex, which may be found at the centre of the upper surface. 

 The lower surface produces roots. This kind of corm is always 

 naked, producing no leaves except those of its apical bud. 



Section III. — The Shoot (continued). 

 B. The Leaves. 



1. GENERAL DESCRIPTION OF THE PARTS OF THE LEAF. 



We have seen that the vegetative appendages which arise 

 upon the stem are of two kinds, those which are like and those 

 which are unlike the axis itself. A leaf may be defined as an 

 appendage borne upon an axis from which it differs in its 

 structure and organisation. Like the stem itself it is capable 

 of branching, and its branches show similar modes of origin to 

 those of the branches of the axis. The ultimate shape of the 



