18 Transactions. 



of pink. The cushions often die away in the centre, these dead parts 

 becoming black. Such cushions during the winter, with their black 

 centre and pinkish-grey periphery, have a peculiar appearance, quite 

 unlike an ordinary plant. 



(4.) Morphology. — -(a.) Stem. — The main stems are prostrate, thin 

 (2 mm. diameter) and wiry, and rather difficult to trace. The secondary 

 branches all tend to take a vertical direction, even at the margins, and in 

 young plants the general trend of all the smaller branches is vertical. The 

 colour of the stem is brownish — rather lighter than in the other species. 

 Owing to the smallness of the leaves not much humus is formed, hence there 

 is no dense coating of dead leaves round the stems. The branchlets vary in 

 length, but compared with those in other species of Raoulia are short (04 cm. 

 to 1cm. long), and, with the leaves, about 1-5 mm. diameter. The leaves 

 are very small, and to the naked eye appear almost like scales or leaf-bases. 

 Lower down the branchlet, and on the lower branches, the dead leaves 

 cling tenaciously, and have still more the appearance of scales ; they are 

 brownish, not blackish as in R. tenuicaulis. The branchlets, taken as a 

 whole, are remarkably equal in length, and so arranged that their rosettes 

 form a very even surface. As stated above, the surface of R. lutescens 

 is the smoothest of all the cushion-plants in the Cass Valley. Owing to 

 the smallness of the leaves the branchlets are able to be very closely com- 

 pacted, so that one cannot insert a finger into the cushion without using 

 considerable force. 



The anatomy of the stem is practically the same as in R. australis. 



(b.) Leaf. — The leaf is much the same as in' R. australis, only smaller 

 (1*25 mm. long) in every respect. Sheath and lamina edges have anthocyan, 

 which gives a brownish tinge to the cushion. The rosette is very minute 

 (1-75 mm. across); about nine leaves are visible from above. The inner 

 leaves are closely crowded together and short, but become larger as the 

 periphery is approached, so that the top of the rosette is more or less flat. 

 These rosettes, forming as it were the units of the surface, and being flat 

 themselves and very closely compacted, form the flat surface so character- 

 istic of this species. 



The leaf-anatomy is practically the same as in R. australis, with the 

 whole structural features just slightly smaller. 



(c.) Root. — This is practically the same as in R. australis ; it is fine and 

 wiry. The original tap-root cannot be made out, its place being taken by 

 hosts of adventitious roots which spring from the prostrate stems. Adventi- 

 tious roots arise in the body of the cushion in older plants, and seem to 

 come from all parts of the upper stems below the first two tiers of branch- 

 lets. (See fig. 5.) 



(d.) Flower and Fruit.- — These are much as in R. australis, but slightly 

 smaller. 



(y.) Mode op Formation of Cushion. 



No very young seedling stages were seen, but several young plants, 

 already commencing to branch, were observed. They had a considerable 

 number of rather closely compacted branchlets of equal length, and their 

 terminal rosettes were already massed into a small surface. This mode of 

 growth is well in accord with the marginal growth of the mature cushion. 

 Compactness, indeed, is the chief feature of this plant throughout all its 

 stages. 



