369 



The starch -grains are compound. 



The rhizome iFig. 20,^), also, resembles in the essen- 

 tials of its structure that of R. glacialis. The outer walls of 

 the cells of the epidermis are somewhat thickened, but often 

 the epidermis is dead, in which case the cells lying with- 

 in become somewhat coUenchymatously thickened; often the 

 outer layers of the latter also die. The cortex contains 

 abundance of starch (June), the grains are compound; the 

 cortical cells are slightly |tangentially elongated, and there are 

 fairly large intercellular spaces , I have not been able to 

 find any phellogen in the rhizome either in this species 

 or in any of the other in my material; as mentioned on 

 p. 344 HoLLSTEiN notes that it occurs in B. glacialis. The 

 vascular bundles vary in number, and are arranged in a 

 circle, each of them surrounded by an endodermis with Cas- 

 pary's dots. They often anatomose, which causes the form, 

 size and number to vary in different sections of the same 

 rhizome. The cambium is capable of division, and the greater 

 part of the wood (vessels -l- parenchyma) and the sieve-tissue 

 is of secondary formation. The endodermis is often somewhat 

 lignified. The pith is like that in R. glacialis. 



The Stem is stiffly erect in contradistinction io R. nivalis 

 in which the stem bends sideways (Simmons); it is rounded and 

 thinly covered with hairs ; the flower-stalk is more hairy than 

 the stem. In herbarium-specimens the lower part of the stems 

 of the preceding year are often found to arise from the rhi- 

 zome below the rosette. 



The structure is essentially like that of the stem of R. 

 nivalis. The cuticle is grooved and the epidermis which con- 

 tains chlorophyll has fairly thick tangential walls. The stomata 

 are on a level v/ith the surface. The cortical tissue is often 

 found to be dead in scattered patches. A great part of the 

 pith in the flowering stem is broken down, leaving a large 

 hollow space in the centre. The vascular bundles (Fig. 20, C) 



