26 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



The remaining Asiatic tender species are few, and various : 



Chaneti Hamet (section Seda Genuina, but anomalous). 



indicum Hamet Unction Sempervivoides. 

 viscosum Praegerj 

 formosanum N. E. Brown" 



Leblancae Hamet 

 Someni Hamet 



.section Epeteium. 



Finally, of the few species of Sedum inhabiting the Atlantic Islands, 

 two are in cultivation belonging to the section Seda Genuina — 

 S. lanceroitense Murray, and S. midum Aiton. 



The only large geographical region where Sedums occur not repre- 

 sented in the species known in cultivation is Central Africa, where 

 a few interesting species are found on high mountains (see p. 6). 



X. Description of Species. 



SECTION I— RHODIOLA. 



Section Rhodiola ScopoU, " Introd. ad Hist. Nat.," 255, 1777 

 {char, anipl). Praeger in Trans. Bot. Soc. Edinh., 27, 107,. 1917. 



Rhodiola Linn., " Genera Plantarum," ed. i. 318, 1777 {pro genere). 



Perennial. Caudex fleshy, crowned with leaves with a broad 

 clasping base (often reduced to membranous, deltoid or semi- 

 orbicular scales, or becoming so with age) from the axils of which leafy 

 flowering-shoots are produced. Flowers 4- or 5-parted, dioecious or 

 hermaphrodite. Hardy plants, mostly Asiatic. 



Linnaeus founded his genus to include a single species, R. rosea, 

 the well-known Roseroot. Scopoli reduced Rhodiola to a section 

 of Sedum, and most authors have followed him in this. While some 

 have limited Rhodiola to species which, like roseum, have unisexual 

 and 4-parted flowers, others have included plants like S. crassipes, 

 which have hermaphrodite 5-parted flowers combined with the 

 characteristic thick scaly Rhodiola rootstock. I have endeavoured * 

 to show that a continuous series of forms leads from the roseum type 

 with dioecious 4-parted flowers, poorly developed scales, and massive 

 rootstocks, through others with hermaphrodite 5-parted flowers and 

 larger scales with a leaf-like tip, to forms like 5. Praegerianum and 

 S. primuloides, with hermaphrodite flowers, well-developed leaves 

 instead of scales crowning the rootstock, and short or slender root- 

 stocks. Some members of each group are in cultivation. 



Series I. Rhodiolae sensu stricto. 

 Flowers usually unisexual and 4-parted, caudex usually elongate 

 or greatly thickened. Carpels usually short and crowned with short 

 styles reflexed in fruit. 



• PRAi£GER, " On the Affinities of Sedum Praegertanum W. W. Smith, 

 with a Tentative Classification of the Section Rhodiola." Trans. Bot. Soc. 

 Edinb., 27, 191 7. 



