130 



PLANT LIFE. 



158. (i) Tendrils. — The leaf blade alone, or some of its 

 branches, or the petiole and blade, may develop as a cylin- 

 drical body, without wini/s and sensi- ™.,,.,rfil 



Hii'll ;jl 



tive, known as a tendril. In the pea, -^5^ WIM 



the stipules become very large, and 



take the function of the reduced blade 



(fig. 156). In other jilants the base 



may be broadly winged for the same 



purpose. 



Fig, 156. 



e iipiKM- Icllkls 

 r\'(j ."IS Inliage. 



Fig, 156, — Portion of shout of pea, with a pinnately comjinund leaf \\ 

 are modified into tendrils and the stipules greatly developed tri 

 About half natural size, — After F'rank. 



Fig, 157. — Piece of the stem of locust {l\:ihi niii Psen dacacia^, showing stipules in the 

 form of thorns. Natural size, — After Kerner, 



159. (2) Thorns. — The lea\'es may de\eloi) into slender 

 conical and sharp-pointed thorns or spines, either branched 

 or unbranched (fig. 390). Sometimes the stipules alone 

 become thorns, as in hjcust and acacia (fig. 157). Neither 

 tendrils nor thorns can be distinguished structuralh- fVoni 

 similar forms of the shoot. 



160. (3) Scales. — In buds, on underground stems and 

 on various parts of the aerial stem, are found small, scale-like 

 leaves of various shapes (ligs, loi, 102, lo^, 109, 13S, 139, 



