| | 1. Main stems above ground erect, rooting only at or near stem base; rhizome conspicuous at base of erect stems |
| S. bigelovii |
| | 1' Main stems above ground prostrate, spreading or pendent, rooting at branch forks; rhizome 0 (older, buried main stems rhizome-like) or inconspicuous |
| |
| | 2. Leaves on prostrate stems unequal, leaves below wider and > leaves above at the same nodes as viewed at 20× |
| |
| | 3. Mature leaf tip acute, not bristly; leaf lanceolate; e Peninsular Ranges, Sonoran Desert |
| S. eremophila |
| | 3' Mature leaf tip bristly, bristle 0.5–1.5 mm, leaf linear to linear-lanceolate; n of Transverse Ranges |
| |
| | 4. Cone 10–30 mm; leaf margins ciliate to minutely dentate in lower half, hairs loosely ascending; n Klamath Ranges, > 1500 m |
| S. densa var. scopulorum |
| | 4' Cone 4–8 mm; leaf margins ciliate from base to near tip, hairs appressed-ascending; mostly foothills around Great Central Valley, < 1500 m |
| S. hansenii |
| | 2' Leaves on prostrate stems equal, leaves below = leaves above as viewed at 20× |
| |
| | 5. Main stem segments between branch forks generally > 3 cm (sometimes less in compact plants on exposed site); lateral stems spreading or pendent; leaves weakly appressed — North Coast |
| S. oregana |
| | 5' Main stem segments between branch forks generally < 3 cm; lateral stems decumbent to erect; leaves ± strongly appressed |
| |
| | 6. Mature leaf acute or abruptly pointed as viewed at 20×, bristle 0 (sometimes bristle-tipped in S. leucobryoides) |
| |
| | 7. Leaf tip acute; leaf margin ciliate throughout, hairs spreading to ascending; s South Coast |
| S. cinerascens |
| | 7' Leaf tip abruptly pointed; leaf margin ciliate below, minutely dentate above middle; e Mojave Desert |
| S. leucobryoides |
| | 6' Mature leaf bristle-tipped as viewed at 20× |
| |
| | 8. Bristles on distal leaves 0.5–1.5 mm, ± soft, together forming conspicuous tufts at stem tip; leaves gray-greeen; stems ± fragile when dry |
| S. asprella |
| | 8' Bristles on distal leaves generally < 1 mm, ± rigid, together not forming conspicuous tufts; leaves pale to dull yellow-green; stems not fragile when dry |
| |
| | 9. Leaf color ± same as stem color; leaf base sessile; plant ± mat-like, prostrate stems evident, lateral stems decumbent to weakly ascending |
| S. wallacei |
| | 9' Leaf color different from stem color; leaf base decurrent; plant ± cushion-like, prostrate stems ± obscure, lateral stems crowded, ascending to erect |
| S. watsonii
|