Betts. — Aiift colrx/ji of Plants of Peridotite Btlt, Xelson. 143 



The phloem is a practicall}' continuous band (only interrupted by a 

 few uniseriate meduHary rays). The xylem contains numerous tracheae, 

 but tlie bulk of the xylem is occupied by tracheides and by wood-fibres 

 of small diameter and with small lumen. 



The medullary rays are few ; they are uniseriate, and the cells have 

 lignified walls. The amount of pith is small ; it consists of small roundish 

 cells, most of which contain tannin. 



14. Metrosideros robusta A. Cunn. 



Usual Growth-form. — " A tall and stout forest-tree, 60-80 ft. or even 

 100 ft. high ; trunk irregular, 3-8 ft. diameter or more ; branches spreading, 

 forming a huge rounded head ; branchlets -l-angled, puberulous. Leaves 

 decussate, 1-1| in. long, elliptic-oblong or ovate-oblong or elliptic-lanceo- 

 late, obtuse, glabrous, very coriaceous ; petioles short, stout, glabrous or 

 puberulous." 



Mineral Belt Growth-form. — A small, rounded, compact bush. 



Anatom^j. 



Leaf (fig. 7). — The upper epidermis consists of small cells with thin 

 walls, but with a verv thick cuticle. The cells of this layer contain small 



Fig. 7. — Melrodderos robusta. Transvei-se section of leaf (x 110). a, tliick cuticle; 



b, epidermis ; c, hypodorma ; d, palisade tissue ; e, xylein ; /, phloem ; 



g, oil-gland. 

 Fig. 8. — Metrosideros robusta. Transver.se section of stem ( X 24). a, tliick cuticle ; 



b, cortex ; c, pericycle fibres ; d, phloem ; e, xyle?n. 



drops of oil. The cells of the lower epidermis are smaller than those of the 

 upper, and the cuticle is thinner and ridged. On both surfaces of the leaf 

 are numerous large oil-glands ; they are more numerous on the lower surface 



