264 MISC. PUBLICATION 303, U. S. DEPT. OF AGRICULTURE 



A large shrub or more commonly a small tree ; introduced from Europe and 

 more or less naturalized in the regions indicated ; commonly produces more 

 viable seeds than S. americana; 104,700 seeds per pound. 



Observations: Three species of birds, including sharp-tailed grouse; song- 

 birds generally; claimed to be a second choice of birds where this and 

 8. americana, grow together. 



Sorbus californica, see Sorbus sitchensis. 

 Sorbus decora, see Sorbus americana. 

 Sorbus dumosa, see Sorbus scopulina. 



Sorbus occidentalis (Wats.) Greene. Alpine mountain-ash. 



8. pumila Raf., Pryus occidentalis Wats., 

 Range: 4, 12. 

 Site: Well-drained, sun. 

 Fruit : Pome, available August-December. 

 A large shrub ; flowers June-August. 



Observations: Oregon jay; Clark's crow. Important locally as browse for 

 livestock, although susceptibility to rust lessens the browse value. 



Sorbus pumila, see Sorbus occidentalis. 



Sorbus scopulina Greene. Greene mountain-ash. 



/S. dumosa Greene. 



Range : 4, 9, 10, 12, 13, 14. 

 Site: Well-drained, moist, sun, shade. 

 Fruit : Pome, available July-December. 



A large shrub to small tree ; flowers in June ; commonly occurs in sandy or 

 gravelly soil. 



Stomach records: Dusky grouse. Where in association with highly palatable 

 species is little cropped by livestock ; elsewhere excellent browse for sheep. 



Sorbus sitchensis Roem. (pi. 40, A). Pacific mountain-ash. 



S. angustifolia Rydb. (?), S. californica Greene, Pyrus sitchensis (Roem.) 

 Piper. 



Range: 4, 12. 



Site: Dry, well-drained, moist. 

 Fruit: Pome, available August-November. 



A large shrub to small tree ; flowers in June ; thicket forming ; occurs in 

 sandy loam and other soils. 



Stomach records: Three species of birds, including Richardson's grouse. 

 Fair browse for sheep, less so for cattle. 



Sphaeralcea davidsonii, see Malvastrum davidsonii. 

 Sphaeralcea fasciculata, see Malvastrum fasciculatum. 



Spiraea spp. Spiraeas. 



Nearly all species are free from insects and diseases ; most occur in neutral 

 soil. 



Stomach records (in addition to specific records) : Ruffed grouse, sharp- 

 tailed grouse; mountain sheep. Observations (in addition to specific records) : 

 Pica, cottontail rabbit. Palatability of the western species to livestock is low. 



Spiraea albla Du Roi. Meadow spiraea. 



Range: 15 (Black Hills), 21, 22, 25, 26, 27, 28. 

 Site: Well-drained, moist, sun. 

 Fruit: Follicle. 



A small shrub : flowers June-August. 



A possible hybrid between this and S. tomentosa has been described as 

 S. subcanescens Rydb. It occurs in region 28. 



Spiraea arbuscula, see Spiraea densiflora. 



Spiraea caespitosa Nutt. Dwarf spiraea. 



Petrophytum caespitosum (Nutt.) Rydb., P. acuminatum Rydb. 

 Range: 4, 9, 10, 11, 13, 15. 

 Site: Dry, sun. 

 Fruit: Follicle. 



A small, mat-forming shrub; flowers in May; occurs on limestone and other 

 soils; will grow over dry bare rocks. 



