422 PLANTS OF NEW ZEALAND 



find one with an internal structure similar to that of the 

 leaf of C. Lyallii. Probably the large palisade cells were 

 insufficiently protected from transpiration, and hence the 

 adoption of the grass-like leaf. The stomata are in hair-filled, 

 longitudinal grooves, on the under surface of the leaf, and thus 

 the exposed transpiration surface is reduced to a minimum. 



We have here, therefore, a remarkable example of the 

 principle, that the shape, and general appearance of the foliage, 

 depend to a greater extent upon environment, and less upon 

 heredity, than is generally supposed. 



In C. sessiliflora the leaves are reduced to an inch or so in 

 length, and the plant consists of hard rosettes surrounding the 

 flower heads, which are sunk amongst the apical leaves ; and in 

 C. argentea the leaves have become needle-like and involute. 

 The leaves are also reduced to needles in C. lateralis and 

 C. laricifolia. It is such remarkable adaptations as these, that 

 have enabled Celmisia to become one of the dominant genera 

 of the New Zealand sub-alpine meadows. 



Though so highly characteristic of mountain regions, the 

 genus is also found on the lowlands, and by the sea-shore. 

 C. longifolia, for example, in one of its many forms, is found 

 throughout New Zealand, from the sea-coast, up to the height 

 of about 5,000 feet. C. Mackaui, however, another very 

 distinct form, is only known with certainty from one spot on 

 Banks Peninsula. There, however, it is fairly plentiful, and 

 is scarcely likely to suffer extinction, unless at the hands of 

 too enthusiastic collectors, so that perhaps it will be wiser not 

 to disclose the exact position of its habitat. 



Some of the Celmisias, like many Olearias and other 

 Composites, have varnished leaves. Some also closely 

 resemble the Andean Asters and Erigerons, and this, 

 doubtless, more because of similarity of habitat, than because 

 of affinity. 



