26 Transactions. 



interior of the bud, but another Composite, Celmisia spectabilis, which grows 

 on the low slopes of the spurs above the old terrace, shows in an interesting 

 manner how terminal branchlets may behave during frost. 



Celmisia spectabilis forms large clumps, often over 1 m. across. It has 

 a mass of stout creeping stems, and the leaves, which average 15 cm. in 

 length, are arranged on the short branchlets to form rosettes about 15 cm. 

 across. 'The lower part of the branchlet, which is composed of the en- 

 sheathing leaf-bases surrounded by the dead and decaying old leaves, is 

 about 4 cm. in diameter. These branchlets are embedded in a coarse filling- 

 material of dead leaves and other organic debris, which during the winter 

 is more or less saturated with moisture. During a severe frost the whole 

 of this filling-material freezes solid. On chopping out a cube from the 

 centre of a frozen clump a complete branchlet can be separated out with 

 some difficulty. All that portion of the branchlet below the large rosette 

 appears frozen hard, but on chopping it through transversely it is seen 

 that only an external shell, about 1 cm. thick, is frozen. This shell consists 

 chiefly of the dead leaf -bases. Within this frozen shell comes the central 

 portion, which consists of numerous young leaves closely packed in 

 tomentum, and quite normal and unfrozen. It is quite obvious from an 

 analogy with Celmisia spectabilis that the central leaves of the Raoulia 

 rosette, closely packed together with tomentum, are eminently adapted to 

 resist such cold as they are likely to experience in the New Zealand 

 mountains. 



(e.) Conclusions. 



It is difficult to understand why this plant should be restricted to the 

 moist old terrace, and R. tenuicaulis, an apparently more herbaceous form, 

 to the lowest grades. An explanation may lie in the behaviour of the 

 stems, which are always buried in the soil. This plant seems to require 

 humus in which to grow. Its large leaves and total lack of filling-material 

 are also mesophytic features. 



, , TT (F.) Raoulia glabra. 



(a.) Habitat. v ' y 



As far as the Cass Valley is concerned, this is a plant of ubiquitous habitat. 

 Though its principal station is on the higher grades of terrace, yet occasional 

 plants are found on the first grade. As will be seen later, its structure is 

 less xerophytic than that of most of the other species of Raoulia dealt with, 

 and its growing-place seems to account for this. It is not in the wide, open 

 spaces of the valley that it is at its best, but in the lateral secondary gullies. 

 Beside the creeks in the bottoms of these gullies occur large mats of this 

 species growing luxuriantly. Specimens have also been observed at an 

 altitude of 1,000 m.* It appears to have wide powers of adaptation, and 

 no definite set of conditions limits its habitat. 



(ft.) Life-form. 



(1.) General. — A "lax mat" best describes the growth-form taken by 

 this species. It is easily the laxest of all the raoulias dealt with. The 

 branches are prostrate, laxly intermingled, and the terminal branchlets 

 are more or less distant from each other. The leaves of some rosettes barely 



* Cheeseinan (1906, p. 331) gives 4,000 ft. as its extreme altitudinal limit. 



