186 SPINES AND TENDRILS OF LEAVES. 
beyond the blade, and become hard and spiny ; in some species 
of Solanum the spines are situated on the surface of the lamina ; 
while in the Barberry (jig. 383) the blade has little or no paren- 
chyma produced between its veins, which are of a spiny cha- 
racter, so that the whole lamina becomes spinous. Spines of 
leaves may be readily distinguished from those already described 
(page 107), which are moditied branches, because in the latter 
case they always arise from the axil of the leaf, instead of from 
the leaf itself. Spines may be also readily distinguished from 
prickles by their internal structure and the other characters al- 
luded to when speaking of the spines of branches (p. 107). 2nd. 
The petiole may assume a spiny character, either at its apex, as in 
some species of Astragalus ; or at its base fromthe pulvinus (fig. 
384, c), asin the Gooseberry. And, 3rd. The stipules may become 
transformed into spines, as in Robinia Pseud-acacia (fig. 275). 
Tendrils of Leaves.—Any part of the leaf may also become 
Fie. 385. Fic. 387. 
Fic. 386. 
Fig. 385, Leaf of a species of Lathyrus, showing a winged petiole, with two 
half-sagittate stipules at its base, and terminated by a tendril.— Fig. 386. 
A portion of the stem of Lathyrus Aphaca, with stipules, s, s,and cirrhose 
petiole, v.— Fig. 387. A portion of the stem of Smilax, bearing a petiolate 
leaf, and two tendrils in place of stipules. 
cirrhose or transformed into a tendril. Thus,—I1st. The midrib 
of the blade of a simple leaf may project beyond the apex, and 
form a tendril, as in Glorivsa superba ; or some of the leaflets of 
a compound leaf may become transformed into branched tendrils 
(figs. 577 and 385), as in certain species of Lathyrus, and many 
other Leguminosz. 2nd. The petiole may become cirrhose, as in 
Lathyrus Aphaca (fig. 386, v), and numerous other plants of the 
Leguminosee. And, 3rd. The stipules may assume the form of 
