GENEEAL MORPHOLOGY OF THE PLANT 91 



specially connected with reproductive structures, including the 

 sporophylls and other leaves of the flower and inflorescence. 



Leaf-spines. — Any part of the leaf may exhibit a spiny 

 character owing to the non-development or diminution of 

 parenchyma, and the hardening of the veins. Thus in the 

 Holly (fig. 12'2) and many Thistles (fig. 80), the veins project 

 beyond the blade, and become hard and spiny ; while in the 

 Barberry (fig. 183) the blade has little or no parenchyma pro- 

 duced between its veins, which are of a spiny character, so that 

 the whole lamina becomes spinous. Spines of leaves may be 



Fig. 183. 



Fig. 181. 



Fig. 183. A portion of a branch of the BarbeiTy (Berberis vulgaris)^ bearing 

 spiny leaves. The upper leaf is composed entirely of hardened veins 



without any parenchyma between them. Fig. 184. A portion of a branch 



of the Gooseberry (Rihes Grossularia). f. Spiny stipules, c. Spine re- 

 placing leaf. 



readily distinguished from the thorns already described, which 

 are modified branches, because in the latter case they always 

 arise from the axil of the leaf, instead of from the leaf itself. 

 Spines may be readily distinguished from prickles by their 

 internal structure. The whole epipodium may assume a spiny 

 character, as in some species of Astragalus, or (fig. 184, c) 

 as in the Gooseberry. The stipules sometimes become trans- 

 formed into spines, as in Eobinia Pseud-acacia (fig. 93). 



Leaf-tendrils. — Any part of the leaf may also become 

 cirrhose or transformed into a, tendril. 1st, The midrib of 

 the blade of a simple leaf may project beyond the apex, and 

 form a tendril, as in Qloriosa superha ; or some of the leaflets of 

 a compound leaf may become transformed into branched tendrils 



