Betts. — Autecology of Plants of Peridotife Belt, Nelson. 



305 



36. Astelia montana (T. Kirk) Cockayne. 



Hahit. — This is a stout, densely tufted, perennial herb. The leaves 

 are numerous, spreading, 1-2 ft. long and |— f in. broad, linear -lanceolate 

 and acuminate. The leaves are very tough and leathery, and are many- 

 veined ; one nerve on each side is more prominent than the rest, and the 

 margins and midrib are often coloured a yellow-red. Both the upper and 

 the lower faces of the leaf are clothed with white tomentum. The base 6i 

 the leaf is sheathing, and is densely covered with long silky hairs. 



Anatomy. 



LeaJ. — Fig. 35 gives diagrammatically a view of a transverse section of 

 half the leaf. From this it will be seen that there are two veins much 

 more prominent than the others, and also more prominent than the midrib. 

 Fig. 36 shows a transverse section through the midrib, and fig. 37 through 

 one of the prominent veins. 



Fig. 35. — Astelia montana. Transverse section of leaf ( X 9). a, tomentum ; 

 b, aqueous tissue ; c, stereome ; d, vascular bundle ; e, chlorenchyma. 



Section through Midrib. — Both the upper and the lower epidermis con- 

 sist of large cells somewhat elongated in a direction at right angles to the 

 surface of the leaf. Above and below the veins the epidermal cells are 

 more or less squarish. The epidermal cells have their walls, especially the 

 external ones, thickened, and there is a cuticle present on both surfaces. 



At intervals on both surfaces the epidermis is interrupted by groups 

 of peculiarly modified cells forming a kind of scale. The scale consists of 

 a short stalk of thin-walled cells, and above this the cells are larger and 

 have thickened, cutinized walls. The cuticle of the uppermost tier of cells 

 is frayed out into a kind of tomentum which more or less covers the surface 

 of the leaf. The whole apparatus appears to be a modification for water- 

 absorjjtion. 



Below the upper epidermis there is a zone of aqueous tissue, consisting 

 of about 4 rows of very large, regularly arranged, closely packed, rectangular 

 cells, which do not contain chloroplasts, and which have thickened, 

 mucilaginous cell-walls. 



