38 



METAMORPHOSED SHOOTS 



(iii.) Spines, Prickles which are subsidiary outgrowths. — 



The leaves and stems of Brambles (fig. 57) and of many Roses 

 have prickles, woody hooks, or long spines scattered over them 

 in indefinite positions. These structures, therefore, represent 

 "subsidiary outgrowths." 



TENDRILS. 



(i.) Leaf-tendrils. — The leaves of the Pea (fig. 59) are pin- 

 nately-compound, and have large green stipules. The positions 



which should be occupied 

 by the terminal leaflet and 

 the two or more pairs of 

 uppermost leaflets are taken 

 by a single terminal tendril 

 and two or more pairs of 

 lateral ones. The tendrils 

 of the Pea, therefore, 

 represent metamorphosed 

 leaflets. 



(ii.) Stem -tendrils. — 

 The tendrils of the 

 Passion - flower arise in 

 the axils of leaves, and 

 are therefore modified 

 branches. 



The tendrils of Bryonia 

 dioica (fig. 57) are not so 

 easily understood. They 

 probably represent meta- 

 morphosed shoots, the leaves of which are absent. 



Fi^. 59. — Compound leaf of Garden Pea. 

 »= stipules ;_/(5/= leaflets ;^y= leaflets converted 

 into tendrils. In this leaf the terminal tendril 

 is wanting. (After Dennert.) 



LEAF- LIKE STEMS (CLADODES). 



The green feathery part of an Asparagus-shoot consists of 

 numerous green stems arising in the axils of minute colourless 

 scales. The Butcher's Broom (Ruscus aculeatus) has short, 

 flattened, leaf-like branches, each terminating in a sharp point. 

 That these leaf-like members are lateral stems is evident from 

 the fact that they bear leaves and flowers, and arise in the axils 

 of the true leaves, which are inconspicuous scales. 



