30 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



dried. It is a familiar member of the alpine flora of our own country, 

 and is one of the most polymorphic of the variable group to which it 

 belongs. Our native form, which is chosen for illustration (fig. 4), 

 displays very little variation within the limits of our islands ; it is 

 sub-var, continentalis of Maximowicz [Bull. Acad. Petersh., 29, 129), 

 and appears to be the form which prevails on the European moun- 

 tains, spreading to Iceland and Canada. In Asia and America the 

 plant becomes variable. Regei. and Tiling (" Flor. Ajanensis," 

 p. 88) enumerate as varieties latifoliwn, vulgare, ohlongum, viride, 

 criapum, pumilum, deniaium, Stephani, humile, involucratum, ovatum, 

 lanceolatum, tenuifolium, Kirilowii. While allowing Stephani and 

 Kirilowii the rank of species, Maximowicz reduces the rest to three 

 varietal types — vulgare, elongatum, and atropurpureum. The form 

 occurring in Japan — Tachiroi of Franchet and Savatier — he admits 

 as a fourth varietal type. Probably Maximowicz's arrangement 

 goes as far as is advisable in the way of subdivision, considering the 

 manner in which the forms run into each other. 



As regards America, six " species " are described under the genus 

 Rhodiola in the " North American Flora " (vol. xxii. 1905) — rosea, 

 neo-mexicana, alaskana, integrijolia, polygama, and roanensis. I 

 have seen only R. rosea, but from the descriptions the others do not 

 seem to differ from the type more than the numerous Asiatic forms, 

 and probably ought at most to be given varietal rank. Further 

 exploration of the American mountain regions will no doubt reveal 

 intermediate and additional forms. 



I have got together in my garden a large series of cultivated forms, 

 received under all kinds of names from many different sources. They 

 show a wide range of variation : — Flowers — unisexual or bisexual, 

 yellow, green, brick -red to dark purple. Leaves— linear-oblanceolate 

 to oblong or broadly obovate, entire to pectinately toothed, green to 

 very glaucous (fig. 5, a). Stem— slender to very stout, 3 inches 

 to a foot high. Rhizome — forming a thick horizontal mass or 

 elongate, very thick and knotted to slender, cylindrical, and smooth. 



I have found much difficulty in allocating these and other forms, 

 which I have been able to study, to Maximowicz's four group-varieties. 

 In the following notes are given first the leading characters of these 

 group-varieties according to Maximowicz's description, and then 

 comments on the cultivated plants which I have studied, which 

 appear to belong to them. 



a. vulgare Maximowicz, Bull. Acad. Peter shourg, 29, 128. 



Illustrations. — See p. 28. 



Height, 7-12 inches. Very glaucous. Leaves imbricate, more or less elliptic, 

 acute. Inflorescence dense, generally leafless. Flowers yellow, longer than the 

 pedicels, stamens exserted, scales twice as long as broad. 



Here belongs the native British and Continental Roseroot, which 

 is also the common garden form. European herbarium specimens 

 show but little variation. The extreme glaucescence is characteristic. 



