Greensill. — Leaf-structure of Coprosma. 347 



guard-cells (g.) are small and pear-shaped ; the subsidiary 

 cells (s.) are slightly modified to fit into them. The cuticle 

 does not show the wavy outline of the upper surface. The 

 pit has numerous unicellular hairs (h.) inside and at the 

 opening ; they are outgrowths of epidermal cells. Next to 

 the pit epidermis are two layers of roundish cells (c. I.), 

 slightly elongated in a transverse direction, and colourless. 

 Next to these is a layer (x.) of cells, intermediate in shape 

 between the colourless layers and the cells of the spongy 

 parenchyma, and containing very few chlorophyll corpuscles. 

 Above this again is the spongy tissue of the leaf. 



Coprosma chathamica. Cockayne, Trans. N.Z. Inst., 



xxxiv., p. 317. 



The under- surface of the leaf is shown in fig. 13. The 

 pits (p.) occur regularly in the axils of the midrib and 

 primary veins. The venation is reticulate. The upper sur- 

 face of the leaf has only a slight protuberance marking the 

 presence of the pits. The structure of the leaf in transverse 

 section (fig. 16) is as follows : On the upper surface a rather 

 thick cuticle (cu.) with slightly wavy outline ; an epidermal 

 layer (ep.) of cells elongated in a transverse direction ; a 

 storage layer (st. I.) of roundish cells, also elongated in a 

 transverse direction ; two or three layers of typical palisade 

 tissue (p. p.), with chlorophyll corpuscles arranged regularly 

 around the walls of the cells. Beneath the palisade tissue 

 is typical spongy parenchyma (sp.), the cells of which are 

 less irregular in shape than are those of all the species 

 already described. They contain chlorophyll corpuscles, also 

 arranged, though with less regularity, along the walls of the 

 cells. On the lower surface is an epidermis (I. ep.) of 

 smaller cells, with a thinner cuticle. The epidermis of both 

 the upper and lower surfaces has numerous outgrowths or 

 hairs (h.), usually unicellular. There are numerous stomata 

 (st.) on the lower surface, which do not differ from those 

 already described. The epidermis of the pit (p. ep.), which 

 is similar to the epidermis of the lower surface, is a single 

 layer of colourless cells (c. I.), round in shape; next to that 

 is a layer (x.) intermediate in shape between the colourless 

 layer and the cells of the spongy parenchyma, and contain- 

 ing very few chlorophyll corpuscles. The hairs (h.) of the 

 pit are long and multicellular ; the individual cells of the 

 hairs are narrow and elongated. 



'o l 



Coprosma petiolata (Chatham Island variety). Hook, f., 

 in Journ. Linn. Soc, Bot., i. (1857), 128. 

 The under-surface of the leaf is seen in fig. 12. The pits 



(p.) are arranged with considerable regularity in the axils of 



