OF THE LEAVES OF CERTAIN SPECIES OF VERONICA. 253 
layer of square cells (fig. 6). The central bundle is large, horseshoe-shaped 
near the base; it ends in a hydathode. It is transcurrent, being connected 
to the upper and lower epidermis by thickened cells. 
This species has been compared with native material from herbaria. The 
latter agrees in all respects with material grown in Edinburgh, except that 
the epidermal walls are thicker in the native material. 
V. Cookiana, Cheesem. 
Leaves large, broad-oval, amplexicaul, 2} x 11 inches. Round the margins 
of the leaves is a row of very stiff hairs. The cuticle is thinner than in 
Section of leaf of V. salicifolia. x 900. 
V. salicifolia, The distinction between palisade and spongy tissues is not so 
sharp; the latter has few interspaces. This may be accounted for by the fact 
that V. Cookiana is characteristic of maritime situations. 
V. elliptica, Forst. 
The leaves are smaller than in V. Cookiana, elliptic, and shortly petioled. 
Around the margin is a dense fringe of hairs, each curved at the end. At 
the tip this band of hairs passes over a peculiar knob-like structure in which 
the bundle ends. Glandular hairs occur on the petiole. Stomata are confined 
to the lower side. The mesophyll is very like that of V. salicifolia; the 
layer of cells above the palisade-tissue contains very few chloroplasts, and 
forms a so-called hypoderm *. Huchedé figures t this hypodermal layer as 
double, but in my material and in herbarium material it is only a single layer 
* Huchedé (1907). T Ibid. fig. iii. 
