158 PLANTS OF NEW ZEALAND 



Let us consider, shortly, how this alpine chickweed has 

 endeavoured to adapt itself to its remarkable habitat. Like 

 nearly all the other shingle plants, it has adopted as its colour 

 the dusky grey of its surroundings. Further, it is the only 

 erect native chickweeed, and thus, by its habit, it is to some 

 extent protected from moving shingle. Dr. Cockayne has 

 grown it from seed, and studied its changes of form.* Seeds 

 collected on Mount Torlesse, and grown at New Brighton 

 (Canterbury) , took more than a year to germinate, and some of 

 them a year and ten months. The first pair of leaves after the 

 cotyledons, were spathulate, and of rather a glaucous green, 

 with long petioles. In the adult plant the leaves are sessile 

 and linear, and thus well protected from excessive trans- 

 piration. This reduction of leaf surface may also be regarded 

 as a protection against excessive insolation. Even in the 

 earlier stages of the plant both surfaces of the leaf are 

 protected by a thick cuticle, and on the under-surface there is 

 in addition a two-layered epidermis. Thus the colour, habit, 

 leaf-form, and leaf-structures are all doubtless adaptations to 

 environment. 



Genus Hectorella. 



A genus of one species, which is a small, tufted, fleshy plant, with leathery, 

 imbricating leaves. The flowers are white, nearly sessile ; stems 1 iii.-lj in. in 

 height. Flowers ^ in. long. Capsule membranous. Named in honour of Dr. 

 Hector who discovered it in the alpine districts of Otago. 



Hectorella caespitosa (The Tufted Hectorella). 



This is a curious alpine patch plant of somewhat uncertain position. It is 

 generally included in the Portulaceae, but as Diels has shown, it should almost 

 cettainly be regarded as one of the Caryophyllaceae. It was originally discovered 

 by Sir James Hector in 1862. The flowers are arranged in circles, on the 

 flattened tops of the branches. It is probable that the structures which Hooker 

 considered to be two sepals, are really sepaloid bracts, and that what he termed 

 the corolla is a petaloid calyx. If these interpretations are correct, then the plant 

 is closely allied to such a Caryophyllaceous plant as Lyallia of Kerguelen's 

 Land. 



*Trans. XXXIII p. 267. 



