182 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



SECTION FARINOSA. 



The commonest and widest-spread species is the worldwide 

 P.farinosa, Linn., which in America as elsewhere shows variations upon 

 the value of which botanical opinions diverge. The typical P. farinosa, 

 Linn.; appears to be spread over Canada and North-Eastern America 

 south of the Arctic; and it shows five microforms — P, americana, 

 Rydberg, a plant of the Rocky Mountains in Montana, Alberta, and 

 Colorado ; P. davurica, Spreng., of Siberia, turns up in Saskatchewan ; 

 in Labrador there is the Asiatic form P. groenlandica, Warming '> 

 P. mistassinica, Michx. — the P. pusilla, Goldie, of the "Botanical 

 Magazine" — extends generally from Newfoundland to the Rockies; 

 then taking a long jump to Patagonia we find P. magellanica, Lehmann, 

 which is unrepresented on the Andes. All these forms have more or 

 less the value of P. farinosa, Linn.; itself as plants of horticultural 

 interest. In the extreme north we have also of this section P. 

 borealis, Duby, and its microform P. Loczii, Pax ; P. integrifolia, 

 Gunner ex Oeder, a microform of P. sibirica ; and P. egalliccensis, 

 Wormskiold. 



American Species of the Farinosa Section. 

 P. americana, Rydberg P. groenlandica, Warming 



P. borealis, Duby P. integrifolia, Gunner ex Oeder 



P. davurica, Spreng. P. Loczii, Pax 



P. egalliccensis, Wormskiold P. magellanica, Lehm. 

 P. farinosa, Linn. P. mistassinica, Michx. 



Section Cuneifolia. 



Of more interest from a horticultural standpoint is the representa- 

 tion of the Cuneifolia section. P. saxifragi folia, Lehmann, one of 

 the microforms of the East Asiatic and Japanese species P. cuneifolia, 

 Ledeb., extends over the Aleutian Islands into Alaska. I do not know 

 if P. cune folia, Ledeb., or any of its microforms has ever been in 

 cultivation, but its appearance in dried specimens indicates that it 

 might be as acceptable as many of the European hirsuta forms with 

 which it has some resemblance. 



More important are P. Rusbyi, Greene, and P. suffrutescens, 

 A. Gray, both of which are known in our gardens. P. Rusbyi, 

 Greene, is a plant of the Rocky Mountains of Arizona and New 

 Mexico, introduced to cultivation by Mr. Dean, of Bedfont, in 1885, 

 with an expression of great expectation for the future, but some- 

 how it has not become common ; it requires apparently special 

 conditions for cultivation. We may gather this from the description 

 of its habitat—" rich and moist soil at comparatively low altitude.'' 

 Beyond it in value as a plant of horticulture is P. suffrutescens, A. 

 Gray. A rock undershrub of exposed situations, it is an easier plant 

 to grow than P. Rusbyi, Greene. In a light, well-drained soil, it thrives 

 at Edinburgh, and there is no more beautiful sight in a rock garden 

 than this plant, with its abundant trusses of pink flowers showing 



