Foweraker. — Mat-plants and Cushion-plants of Cass River Bed . 25 



(6.) Leaf. — The general shape is oblong-spathulate, but the lateral 

 edges are almost parallel, and widen out but little towards the tip. The 

 length is about 4 mm., and greatest width 1 mm. The lamina is concave 

 upwards, more so towards the tip, which is subacute with a blunt terminal 

 papilla. The upper surface is covered with short glandular hairs ; so, 

 too, the under-surface, except over the upper half, which has long sticky 

 white hairs, which reach round and lap over the edge of tip. The "sheath 

 is no wider than the lamina. 



The rosettes are spreading. As the branchlets are not closely compacted 

 together, each rosette stands out well, and, although most of them touch 

 some barely do so, while others are free and solitary. The leaves are 

 spreading and more or less recurved, and from twelve to twenty leaves are 

 visible from above. This rosette is the largest among the raoulias considered. 



Generally the leaf-anatomy is much as in R. tenuicaidis, but the structure 

 is more xerophytic — e.g., cuticle thicker, especially on the upper surface ; 

 chlorenchyma a double row of cylindrical cells on the upper surface, and 

 a single row below ; water-tissue, hairs, stomata, &c, are similar to those 

 in R. tenuicaidis. 



(c.) Root. — The roots are rather straight, very wiry, and dark brown 

 in colour. In many respects they resemble those of R. Haastii. 



The older roots are strongly lignified. There is a central cylinder of 

 xylem, with numerous very large vessels scattered irregularly through it. 

 The phloem consists of a very thin zone, and external to this is a strongly 

 lignified pericycle. The endodermis is conspicuous, and external to this 

 is the suberized and rapidly disappearing cortex. 



(d.) Flower and Fruit. — Capitula large, 0-8 cm. diameter. In vomeral 

 bracts in about three series, the inner with conspicuous white radiating 

 tips. Florets about twenty, outer series female. Cypsela glabrous. Pappus- 

 hairs copious, soft, slightly thickened at the tips. 



(y.) EPHARMONIC VARIATIONS. 



When this plant grows in dry exposed situations its growth tends to be 

 more compact — -the branchlets are shorter and the rosettes smaller. In 

 moist situations the growth tends to become lax and luxuriant. Green- 

 house cultures showed an elongation of the branchlets and an increase in 

 the size of the leaf. 



(<§.) Effect of Frost. 



Growing, as this plant does, in a usually moist humus substratum, the 

 effects of freezing during the winter can be studied better than in the 

 " river-bed " species, which grow on the usually dry shingle. In July, 

 at noon, on a dav after a severe frost, a few temperature observations 

 were made on mats of R. subsericea growing on a moist slope of a low spur. 

 The meteorological conditions were as follows : Sun obscured by drifting 

 clouds ; slight drizzling rain ; north-west wind ; snow falling on high 

 ridges ; temperature of air 6-25° C. The soil had been frozen hard during 

 the night, and had thawed but little by noon. The temperature of the soil 

 at the base of the mat was 0° C, while among the branchlets it was 4° to 

 5° C. It is quite evident that the rosettes were exposed to the full influence 

 of the frost, but owing to the thick cuticle, the tomentum, and the terminal 

 bud structure they could withstand it. The smallness of the rosettes in 

 R. subsericea prevents temperature readings being taken in the field of the 



