318 



Transactions. 



(ii.) Leaj -anatomy. 



(a.) Shade Leaj. — Epidermis: Cells flattened, thin-walled, outer walls very 

 convex ; lower epidermal cells smaller ; cells beneath midrib tliick-walled. 

 Stoma ta : Lower surface only, level with epidermal cells. Chlorenchyma : 

 Palisade — 1 layer cells, slightly elongated, and rather loosely packed 

 Spongy — 5-6 layers ; upper cells nearly spherical, lower cells more or less 

 elongated, parallel to leaf-surface ; intercellular spaces large. Chlorophyll 

 abundant both in palisade and in spongy tissues. Vascular bundles sur- 

 rounded by poorly developed bundle-sheath. Calcium oxalate in raphides. 



(&.) Sun Leaf. — Epidermis : Walls slightly thickened. Chlorenchyma : 

 Palisade — Cells more elongated and more closely packed than in shade 

 leaves. Spongy — Cells more regular ; intercellular spaces smaller. 



2. The Species of Rubus. 

 There can be no doubt that the species of Rubus in New Zealand are 

 poorly defined. Cheeseman did not recognize R. subpauperattis in the 

 Manual, but from the following descriptions it will be seen that there 

 are sufficient grounds for the establishment of Cockayne's species (1909a, 

 p. 42). The different species show many points of similarity in their life- 

 form, but there are some characteristics which, though common to all, 

 are more noticeable in particular species.* 



Fig. 1. — Riibu3 australis. Leaf; top view. 

 Fig. 2. — Rubus australis. Leaf ; side view. 



The leaves are alternate and palmately compound (see figs. 1 and 2), 

 with 3-5 leaflets, which vary in size. Margins serrate, with incisions to 



* In the descriptions below, therefore, the special points of each species are more 

 fully dealt with. Further, the descriptions cannot be rigidly applied to all the members 

 of a species, on account of the diversity of form of the individual plants ; and, in fact, 

 it is probable that hybrids are of common occurrence. 



