24. Saxifraga cespitosa Linnaeus, Sp. Pl. 1: 404. 1753.
Tufted or tufted alpine saxifrage, saxifrage cespiteuse
Muscaria delicatula Small; M. micropetala Small; M. monticola Small; Saxifraga cespitosa subsp. decipiens (Ehrhart) Engler & Irmscher; S. cespitosa var. emarginata (Small) Rosendahl; S. cespitosa subsp.exaratoides (Simmons) Engler & Irmscher; S. cespitosa subsp. laxiuscula (Engler & Irmscher) Á. Löve & D. Löve; S. cespitosa var. lemmonii Engler & Irmscher; S. cespitosa var. minima Blankenship; S. cespitosa subsp. monticola (Small) A. E. Porsild; S. cespitosa subsp. sileneflora (Sternberg ex Chamisso) Hultén; S. cespitosa subsp. subgemmifera Engler & Irmscher; S. cespitosa var. subgemmifera (Engler & Irmscher) C. L. Hitchcock; S. cespitosa subsp. uniflora (R. Brown) A. E. Porsild
Plants densely cushion- to loosely mat-forming, (stems trailing), not stoloniferous, not rhizomatous, with ± woody caudex. Leaves basal and proximal cauline, (marcescent, crowded); petiole flattened, 2-6(-12) mm; blade elliptic to obovate or spatulate, 3(-5)-lobed apically (lobes oblong-elliptic), 4-15(-25) mm, ± fleshy, margins entire, sparsely short glandular-ciliate (mostly proximally), (nonsecreting hydathodes present adaxially at each lobe apex), apex obtuse, surfaces sparsely to densely short stipitate-glandular. Inflorescences 2-5-flowered cymes, sometimes solitary flowers, to 2-15(-20) cm, densely clear- or cream- to pinkish yellow-tipped stipitate-glandular; bracts sessile. Flowers: sepals erect to spreading, triangular or ovate to elliptic, margins stipitate-glandular, surfaces stipitate-glandular; petals white, proximally greenish to yellowish tinged, not spotted but sometimes striate, elliptic or oblanceolate to obovate, (1.5-)3-7(-15) mm, equaling or longer than sepals; ovary inferior. 2n = 78, 80.
Flowering summer. Rock outcrops, crevices, talus, scree slopes, rocky tundra, fellfields, nunataks, stream banks; 0-4500 m; Greenland; Alta., B.C., Man., Nfld. and Labr., N.W.T., Nunavut, Ont., Que., Yukon; Alaska, Ariz., Calif., Colo., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo.; Europe; Asia (Siberia).
The North American representatives of Saxifraga cespitosa are very variable. It seems futile at this time to recognize any of the infrapecific taxa that have been described, although five are frequently distinguished as either subspecies or varieties. Expressions of all of the purported distinguishing characters overlap or have little apparent geographic or ecologic correlation. The only Southern Hemisphere representatives of Saxifraga are closely related to S. cespitosa. Reports of S. rosacea Moench from southern Greenland are misidentifications of this species.