104 



TENDRIL OR CIRRHUS. 



cirrhatum, and Albuca cirrhata, the midrib of the leaf ends in a ten- 

 dril; and hi Vetches, the terminal leaflet, and some of the lateral ones 

 at the extremity of their pinnate leaves, are changed, so as to form a 

 branching tendril. In the Vine, the tendrils are looked upon as the 

 terminations of separate axes, or as transformed terminal buds. In this 

 plant there are no young buds seen in the angle between the stem and 

 leaves, nor between the stem and tendrils; and the latter are not axillary. 

 Fig. 221 represents the branch of a Vine, hi which a! is the primary or 



first formed axis, ending inv', 

 a tendril, or altered terminal 

 bud, and having a leaf, f,' on 

 one side. Between this leaf 

 and the tendril which repre- 

 sents the axis, a leaf-bud was 

 formed at an early date pro- 

 ducing the secondary axis, 

 or branch, a", ending in a 

 tendril, v", with a lateral leaf, 

 f", from which a tertiary axis 

 or branch, a'" was developed, 

 ending in a tendril, v'", and 

 so on. 



202. Tendrils twist in a 

 spiral manner, and enable the 

 plants to rise into the air by 

 twining round other plants. 

 The direction of the spiral 

 frequently differs from that 

 of the climbing stem, pro- 

 ducing the tendril. In the Vine, the lower part of the stem is strong, 

 and needs no additional support; the tendrils therefore occur only 

 in the upper part where the branches are soft, and require aid to 

 enable them to support the clusters of fruit. In Vanilla aromatica, 

 the vanille plant, tendrils are produced opposite the leaves, until the 

 plant gains the top of the trees by which it is supported; the upper ten- 

 drils being then developed as leaves. The midrib is sometimes prolonged 

 in a cup-like form: this is occasionally seen in the common cabbage, 

 arid seems to depend on the vascular bundles of the midrib spreading 

 out at their extremity in a radiating manner, and becoming covered 

 with parenchyma in such a way as to form a hollow cavity in the centre. 



Fig. 221. Portion of a branch of the Vine (Vita viniferd). a', First axis, terminated by a 

 tendril or cirrhus, -', which assumes a lateral position, and bears a leaf, /'. From the axil of this 



also by a ten _ 

 terminated by 

 arises. 



cirrhus, t', which assumes a lateral position, arid bears a leaf, /'. From the axil of this 

 ond axis, a", comes off, which seems to be a continuation of the first, and is terminated 

 tendril, v', bearing a leaf,/''. From the axil of this second leaf, a third axis, "', arises 

 d by a tendril, v"', and bearing a leaf, /'", from the axil of which a fourth axis a '", 



