SMALL LEAVES 189 



confined to the gymnosperms. Thus Hakea sulcata, and 

 other species of this AustraHan genus, have long needle 

 leaves. 



Scale leaves of the cupressoid type are seen in the suc- 

 culent saltworts {Salicornia herbacea), and in the tamarisk 

 {Tamarix gallica). A remarkable case of convergence is 

 shown by the New Zealand Veronica ciipressoides, in which 

 the shoots are so entirely cupressoid in appearance that it 

 is not possible to say from a cursory inspection of a 

 vegetative shoot that the plant is not a cypress. 



Marked xerophytism is also exhibited by the pure linear 

 and setaceous leaf forms of grasses, sedges, and other plants, 

 such as Linum catharitciim, the purging flax, and Linaria 

 vulgaris, the toad-flax. Taken in conjunction with stomatal 

 protection, this type also secures reduced transpiration. 

 There is no sharp line of demarcation between the linear 

 leaf and typical broad shapes. Indeed transitions may be 

 traced in a single individual as in Campanula ; or inside a 

 genus, as in different species of Galium. The narrower 

 the leaf, and the more vertical its position, the more 

 transpiration is reduced. The leaves of some rushes are 

 cylindrical. 



Another distinctively xerophytic leaf type may be termed 

 " cricoid " as it is seen in many species of Erica. It is also 

 found in Loiseleuria procurnbens, the creeping azalea, of the 

 Scottish mountains and arctic countries, Empetrum nigrum, 

 the crowberry, Dabeocia polifolia, Passer ina sps., and other 

 South African plants (cp. Thoday, 1921). In shape it is 

 variable, rather narrow or even needle-like ; it is marked 

 by its small size, leathery texture, and evergreen habit, and 

 by characters already noted — the protection of the stomata, 

 which lie in grooves often clad with hairs, and the tendency 

 of the leaf margins to roll in, which may be accentuated in 

 drought. Between such leaves and the broad sclerophyllous 

 foliage of Vaccinium Vitis-Idcea, or of a Rhododendron, 

 there is no sharp demarcation. The small-leaved, hairy 

 Rhododendrons — Rhododendron ferrugineum of the Alps — 

 come near the Loiseleuria type, as does Myrica Gale. 



