191«-17.] BOTANICAL SOCIETY OF EDINBURGH 111 



development.^ Following on the two seed-leaves (seen in 

 fig. 13) a rosette of scale-leaves similar to those just 

 described is produced. Fig. 13 shows a seedling three 

 months old. The next drawing (fig. 14) illustrates a plant 

 a month older, with the first flower-shoot arising from the 

 axil of one of the lower scale-leaves. The close simi- 

 larity of these scale-leaves of S. crassipes to the leaves of 

 S. Praegerianum does not need emphasising. 



Here, then, we find the explanation of the peculiar 

 characters of S. Praegerianum and ;S'. primuloides — their 

 rosettes of leaves, their clasping leaf-base and axillary 

 flower-shoots, and their flowers akin to those of some of 

 the hermaphrodite Rhodiolas. It seems clear that they are 

 primitive Rhodiolas in which are still preserved the leaves 

 which clothed the root-stock of ancestral forms; these 

 leaves, in the majority of living species, being represented 

 merely by membranous scales. Thus viewed, as members 

 of the Rhodiola section, aS^. Praegerianum and S. primu- 

 loides, apart from their peculiar leaf-rosette, fall easily 

 within the limits of that group as hitherto understood, 

 which embraces a considerable variety of plant forms. The 

 root-stocks of both, though approaching those of typical 

 Rhodiola, are unusual — the former by reason of its extreme 

 shortness, and the latter on account of its slenderness and 

 repeated branching. For the characters of the flower-stems, 

 stem-leaves, inflorescence and flowers, analogues can easily 

 be found among the Asiatic Rhodiolas. 



It may be added here that among the Mexican Sedums, 

 which show a very wide range of growth-forms, the primu- 

 loides type sometimes occurs — in S. Palmeri, S. Wats, and 

 S. compressuon, Rose, for instance, where leaf-rosettes borne 

 at the ends of the branches give rise to axillary leafy 

 flower-shoots bearing terminal cymes; in S. nutans, Rose 

 (Cremnophila nutans, Rose), where similar axillary leafy 

 shoots bearing large elongated panicles are produced from 

 ample loose rosettes ; and in *S'. pachyphyllum, Rose, in 

 which the leafy axillary flower-shoot arises from a stem 

 which is more elongate than those of the species just men- 

 tioned, and which is clothed with leaves for the greater 



' Some account of tlie seedling stage of this species and of S. roseum 

 will be found in Lubbock, Seedlings, i, 514-516. 



