| | 1. Dwarf alpine shrub, < 0.2 m, forming mats by layering or rhizomes |
| |
| | 2. Young leaves hairy; mature leaf blade 20–40 mm, not strongly net-like below, puberulent on both surfaces; plant forming colonies by adventitious rooting of stems |
| S. arctica |
| | 2' Young leaves glabrous; mature leaf blade 6–22 mm, strongly net-like below, glabrous on both surfaces; plant forming rhizomatous mats |
| S. reticulata subsp. nivalis |
| | 1' Low shrub to tree, not alpine, > 0.2 m, not mat-forming |
| |
| | 3. Tree; margins of bud scale free and overlapping |
| |
| | 4. Leaf blade not glaucous below; twigs yellowish or yellow-gray |
| S. gooddingii |
| | 4' Leaf blade glaucous below; twigs yellow- or red-brown |
| S. laevigata |
| | 3' Shrub or tree; margins of bud scale fused |
| |
| | 5. Petiole with glands at base of blade |
| |
| | 6. Tree, 7–25 m, alien; twigs pendent or erect, brittle at base; petioles tomentose or silky |
| |
| | 7. Stems generally erect (pendent); twigs yellow, gray-brown, or red-brown; twigs and young leaves densely silky; petioles silky; stipules acute at tip |
| S. alba |
| | 7' Stems pendent ± to ground; twigs yellow- to gray-brown; twigs and young leaf blade sparsely long-soft-wavy-hairy, becoming glabrous; petioles tomentose; stipules acuminate at tip |
| 2 S. babylonica |
| | 6' Shrub or small tree, 0.6–10 m, native; twigs erect, flexible or brittle at base; petioles glabrous or long-soft-wavy-hairy |
| |
| | 8. Leaf blade tomentose or silky, tip acute; stipules not strongly glandular; twigs dull or shiny; shrub 0.4–6 m |
| 2 S. eastwoodiae |
| | 8' Leaf blade becoming glabrous, tip ± long-acuminate (rarely acute); stipules glandular; twigs highly glossy; tall shrub or small tree 1–10 m |
| S. lucida |
| | 5' Petiole lacking glands at base of blade |
| |
| | 9. Leaf blade not glaucous below |
| |
| | 10. Leaf blade margins entire or sparsely fine-dentate with well separated teeth; plant clonal by root-sprouting; petiole glabrous or silky, 2–6 mm |
| |
| | 11. Leaf blade linear (length 10–23 × width); young leaves silky |
| 2 S. exigua |
| | 11' Leaf blade narrowly elliptic to narrowly obovate (length 2.8–8.5 × width; young leaves long-soft-wavy-hairy, tomentose, or velvety |
| |
| | 12. Petiole glabrous; twigs gray-brown; leaf tip acute, both surfaces becoming glabrous to moderately tomentose or long-soft-wavy-hairy |
| S. melanopsis |
| | 12' Petiole hairy; twigs red-brown; leaf tip acuminate, both surfaces densely silky or long-soft-wavy-hairy |
| S. sessilifolia |
| | 10' Leaf blade margins entire to finely serrate; plant not clonal; petiole soft-shaggy-hairy, tomentose, or velvety, 3–17 mm |
| |
| | 13. Leaf blade margins strongly rolled under; young leaves woolly or silky |
| 2 S. sitchensis |
| | 13' Leaf blade margins flat or slightly rolled under; young leaves soft-shaggy-hairy, tomentose, woolly, or silky |
| |
| | 14. Young leaves shaggy-hairy; mature leaf blade glabrous or soft-shaggy-hairy below, shiny to highly glossy above |
| S. boothii |
| | 14' Young leaves densely tomentose, silky, or woolly; mature leaf blade tomentose, long-soft-wavy-hairy, woolly-tomentose, silky, or becoming glabrous below and dull above |
| 2 S. eastwoodiae |
| | 9' Leaf blade glaucous below or surface obscured by hair |
| |
| | 15. Leaf blade linear (length 10–23 × width); young leaves silky; clonal by root-sprouting |
| 2 S. exigua |
| | 15' Leaf blade narrowly elliptic or wider; not clonal by root-sprouting |
| |
| | 16. Tree, 7–25 m, alien; twigs pendent ± to ground; stipule tip ± long-acuminate |
| 2 S. babylonica |
| | 16' Shrub or tree, 0.2–10 m, native; twigs decumbent or erect; stipule tip rounded to acute |
| |
| | 17. Leaf blade margins strongly rolled under |
| |
| | 18. Leaf blade densely woolly or silky below, surface obscured by white hair, dull above; margin of first leaves on shoot glandular-dotted to finely serrate |
| 2 S. sitchensis |
| | 18' Leaf blade silky, tomentose, or woolly below, often with mixture of white and rusty hairs, glaucous below, shiny above; margin of first leaves on shoot entire |
| S. scouleriana |
| | 17' Leaf blade margins flat or slightly rolled under |
| |
| | 19. Leaf blade highly glossy above |
| |
| | 20. Leaf blade moderately to densely shaggy, tomentose, or woolly below |
| |
| | 21. Twigs generally glaucous; leaf blade generally woolly or shaggy-hairy below, 18–55 wide, length 1.6–4.2 × width |
| S. hookeriana |
| | 21' Twigs not glaucous; leaf blade generally tomentose below, 6–32 mm wide, length 3.2–9.6 × width |
| 8 S. lasiolepis |
| | 20' Leaf blade glabrous (or soon becoming so) to sparsely silky below |
| |
| | 22. Petiole tomentose or velvety; leaf blade 35–125 mm; twig hairs spreading; leaf blade glands slightly on upper surface of blade; generally 0–2500 m |
| 8 S. lasiolepis |
| | 22' Petiole sparsely soft-shaggy-hairy; leaf blade 20–54 mm; twig hairs appressed or curved toward stem; leaf blade glands at margin of blade; 2500–4000 m |
| S. planifolia subsp. planifolia |
| | 19' Leaf blade dull to shiny above |
| |
| | 23. Leaf blade glabrous, downy, or soft-shaggy-hairy below |
| |
| | 24. Leaf blade with white hairs, sometimes mixed with rusty hairs |
| |
| | 25. Stipules generally leaf-like, sometimes vestigial; young leaves and leaf blade generally short-tomentose, sometimes densely silky; 0–2500 m |
| 8 S. lasiolepis |
| | 25' Stipules 0 or vestigial on first leaves, leaf-like on later leaves; young leaves and leaf blade generally densely silky; 1400–3600 m |
| |
| | 26. Leaf blade 32–74 mm, persistently long-(often white)-hairy; petiole 3–9 mm; stipules generally 0 or vestigial |
| 5 S. geyeriana |
| | 26' Leaf blade 44–102 mm, becoming ± glabrous or sparsely short-(generally rusty)-hairy; petioles 5–16 mm; stipules vestigial on first leaves, leaf-like on later |
| 3 S. lemmonii |
| | 24' Leaf blade with white hairs only |
| |
| | 27. Stipules 0 or vestigial on first leaves, leaf-like on later leaves |
| |
| | 28. Young leaves and leaf blades generally densely silky; twigs generally glaucous; 1450–3600 m |
| 5 S. geyeriana |
| | 28' Young leaves and leaf blades generally short-tomentose (sometimes densely silky); twigs not glaucous; 0–2500 m |
| 8 S. lasiolepis |
| |
| | 29. Leaf blade generally with ridge-like, netted veins below, blade length 2–3.8 × width, margin entire to shallowly crenate; twigs long-soft-wavy-hairy; young leaves densely silky — n Modoc Plateau |
| 2 S. bebbiana |
| | 29' Leaf blade smooth below, blade length 2.2–9.6 × width, margin generally finely serrate (sometimes entire in S. lasiolepis); twigs tomentose or velvety, generally becoming glabrous; young leaves generally glabrous or very sparsely hairy (densely silky in S. lasiolepis) |
| |
| | 30. Leaf base wedge-shaped to acute; blade shiny above; twigs tomentose, becoming glabrous |
| 8 S. lasiolepis |
| | 30' Leaf base acute to rounded or ± cordate; blade dull above; twigs glabrous to sparsely long-soft-wavy-hairy |
| |
| | 31. Twigs yellowish or grayish, smooth |
| S. lutea |
| | 31' Twigs generally red-brown, peeling |
| |
| | 32. Leaf blade lanceolate to elliptic (length 2.9–6.4 × width), base acute to rounded (rarely cordate); stipule tip acute |
| S. ligulifolia |
| | 32' Leaf blade lanceolate to ovate (length 2.4–4.5 × width), base generally cordate; stipule tip rounded |
| S. prolixa |
| | 23' Leaf blade long-soft-wavy-hairy, tomentose, silky, or velvety below |
| |
| |
| | 34. Leaf blade dull above |
| |
| | 35. Leaf blade very densely white-silky below (some hairs sometimes rusty); young leaves short-silky; twigs brittle at base |
| 2 S. drummondiana |
| | 35' Leaf blade sparsely to moderately densely white-silky below; young leaves long-silky; twigs flexible at base |
| 3 S. orestera |
| | 34' Leaf blade shiny above |
| |
| | 36. Leaf blade hairier below than above (but midrib glabrous below), generally densely white-silky to -tomentose; young leaves short-silky |
| 2 S. drummondiana |
| | 36' Leaf blade equally hairy above and below or becoming glabrous (midrib below generally hairy like blade), hairs white, rusty, or mixed; young leaves silky |
| |
| | 37. Leaf blade 32–74 mm, persistently long-(generally white)-hairy (sometimes mixed with rusty); petiole 3–9 mm; stipules generally 0 or vestigial |
| 5 S. geyeriana |
| | 37' Leaf blade 44–102 mm, becoming glabrous or short-(generally rusty)-hairy; petiole 5–16 mm; stipules vestigial on first leaves, leaf-like on later leaves |
| 3 S. lemmonii |
| |
| | 38. Young leaves sparsely or moderately hairy; petiole puberulent; twigs long-soft-wavy-hairy — n Modoc Plateau |
| 2 S. bebbiana |
| | 38' Young leaves very densely hairy; petiole tomentose, silky, or velvety; twigs soft-shaggy-hairy, tomentose, silky, velvety, or becoming glabrous |
| |
| | 39. Leaf blade ± widely elliptic or widely obovate (length 1.3–2.8 × width); petiole velvety (or tomentose); young leaves velvety (or silky); leaf tip obtuse to rounded |
| S. delnortensis |
| | 39' Leaf blade ± narrowly elliptic or narrowly obovate (length 2.8–7.3 × width); petiole tomentose (or silky or velvety in S. jepsonii); young leaves silky; leaf tip acute to acuminate (or obtuse in S. jepsonii) |
| |
| | 40. Subalpine shrub < 1 m; leaf blade 10–95 mm; 2100–4000 m |
| |
| | 41. Leaf blade 10–20 mm, shiny above; petiole silky; young leaves very densely hairy; rare, e slope c High Sierra Nevada (Mono Co.) |
| S. brachycarpa subsp. brachycarpa |
| | 41' Leaf blade 35–95 mm, dull above; petiole soft-shaggy-hairy; High Sierra Nevada |
| 3 S. orestera |
| | 40' Shrub > 1 m; leaf blade 32–144 mm; 0–2800 m (± 3600 m in S. geyeriana, S. lemmonii, S. jepsonii) |
| |
| | 42. Leaf blade with white and rusty hair |
| |
| | 43. Stipules generally leaf-like (or vestigial); young leaves and leaf blade generally short-tomentose, sometimes densely silky; 0–1900 m |
| 8 S. lasiolepis |
| | 43' Stipules 0 or vestigial on first leaves, generally leaf-like on later leaves; young leaves and leaf blade generally densely silky; 1450–3600 m |
| |
| | 44. Leaf blade 32–74 mm, persistently long-(often white)-hairy; petiole 3–9 mm; stipules generally 0 or vestigial |
| 5 S. geyeriana |
| | 44' Leaf blade 44–110 mm, becoming glabrous or short-(generally rusty)-hairy; petiole 5–16 mm; stipules vestigial on first leaves, leaf-like on later leaves |
| 3 S. lemmonii |
| | 42' Leaf blade with white hairs only |
| |
| | 45. Petiole silky or velvety |
| |
| | 46. Leaf blade 32–74 mm, generally densely silky on both surfaces; stipules generally 0; petiole velvety |
| 5 S. geyeriana |
| | 46' Leaf blade 35–144 mm, generally becoming glabrous or hairier below; stipules generally leaf-like |
| |
| | 47. Leaf blade densely silky below, dark green above; margin of first leaves on shoot gland-dotted |
| S. jepsonii |
| | 47' Leaf blade sparsely or moderately hairy below, not dark green above; margin of first leaves on shoot glandless |
| 8 S. lasiolepis |
| | 45' Petiole tomentose or soft-shaggy-hairy |
| |
| | 48. Leaf blade silky on both surfaces; stipule tip acute |
| 3 S. orestera |
| | 48' Leaf blade tomentose below, long-soft-wavy-hairy or tomentose above; stipule tip rounded |
| |
| | 49. Leaf blade generally densely tomentose below; twigs generally velvety; on serpentine — hybridizes with S. lasiolepis |
| S. breweri |
| | 49' Leaf blade generally sparsely or moderately tomentose; twigs generally sparsely tomentose; not always on serpentine |
| 8 S. lasiolepis
|
| |
| | 2. Flower bract deciduous after flower, tawny, sparsely hairy, tip often ragged |
| |
| | 3. Margins of bud scale free and overlapping; tree |
| |
| | 4. Leaf blade not glaucous below; beak of ovary abruptly tapered to style |
| 2 S. gooddingii |
| | 4' Leaf blade glaucous below; beak of ovary gradually tapered to style |
| S. laevigata |
| | 3' Margins of bud scale fused; shrub or tree |
| |
| | 5. Petiole with glands near base of blade; plant not clonal; stigmas persistent after flower |
| |
| | 6. Tree 10–25 m; stipules not conspicuously glandular; fruit 3.5–5 mm; twigs golden-yellow, gray-, or red-brown; alien |
| S. alba |
| | 6' Tree or shrub 1–10 m; stipules conspicuously glandular; fruit 6–11 mm; twigs yellow-brown; native |
| S. lucida |
| | 5' Petiole glands 0; plant spreading clonally by root-sprouting; stigmas deciduous after flower |
| |
| | 7. Fruit hairy, at least when young; flower bract tip acute to obtuse; young leaves silky |
| 2 S. exigua |
| | 7' Fruit glabrous; flower bract tip rounded; young leaves soft-shaggy-hairy |
| S. melanopsis |
| | 2' Flower bract persistent after flower, tawny to black, generally hairy, tip entire |
| |
| | 8. Tree, alien; twigs pendent ± to ground; nectary > stalk |
| S. babylonica |
| | 8' Shrub or tree, native; twigs erect; nectary < stalk |
| |
| | 9. Flower bract dark brown, widest at round tip, hairs dense, short, generally wavy, ± equal; twigs tomentose, brittle at base; hairs of young leaves white and sometimes also rusty |
| 2 S. lasiolepis |
| | 9' Flower bract not as above in all ways; twigs variously hairy, flexible at base (except some S. hookeriana); hairs of young leaves white only |
| |
| | 10. Leaf blade not glaucous below |
| |
| | 11. Catkins generally appearing before the leaves, sessile; leaf blade glabrous, becoming so, or soft-shaggy-hairy and highly glossy above; ovary generally glabrous |
| S. boothii |
| | 11' Catkins appearing with the leaves, on distinct leafy shoots; leaf blade tomentose or silky and dull to shiny above; ovary generally silky (sometimes glabrous) |
| 3 S. eastwoodiae |
| | 10' Leaf blade glaucous below |
| |
| | 12. Stipules 0 or vestigial on early leaves, 0 or prominent on later leaves; flower bract hairs straight or wavy |
| |
| | 13. Style 0.6–1.4 mm; fruit 6–7 mm; twigs thinly glaucous; leaf blade length 1.6–3.9 × width, soft-shaggy or woolly below; flower bract with long, straight hairs, tip sometimes pointed |
| 3 S. hookeriana |
| | 13' Style 0.1–0.6 mm; fruit 2.5–5.5 mm; twigs not glaucous; leaf blade length 2.2–9.6 × width, tomentose or silky below (but becoming glabrous); flower bract with short, wavy hairs, tip generally widest at round tip |
| 2 S. lasiolepis |
| | 12' Stipules prominent on all leaves; flower bract hairs generally curly (rarely straight) |
| |
| | 14. Twigs yellow or gray-yellow, smooth, not peeling; twigs glabrous or sparsely soft-shaggy-hairy |
| S. lutea |
| | 14' Twigs red-brown, sometimes yellow-brown, generally peeling; twigs glabrous or long-soft-wavy-hairy |
| |
| | 15. Ovary on stalk 0.9–2.5 mm; leaf blade lanceolate to elliptic (length 2.9–6.4 × width), base acute to rounded (rarely cordate); stipule tip acute |
| S. ligulifolia |
| | 15' Ovary on stalk 1.3–4.2 mm; leaf blade lanceolate to ovate (length 2.4–4.5 × width), base generally cordate; stipule tip rounded |
| S. prolixa |
| |
| | 16. Dwarf alpine shrub, forming mats by adventitious rooting of stems or by rhizomes |
| |
| | 17. Catkins > 20-flowered; flower bract hairy; nectary 0.6–1.2 mm; style 0.4–1.6 mm; leaf veins not strongly net-like below |
| S. arctica |
| | 17' Catkins < 20-flowered; flower bract glabrous; nectary ± 0.2 mm; style 0.1–0.4 mm; leaf veins strongly net-like below |
| S. reticulata subsp. nivalis |
| | 16' Low to tall shrub or tree; not forming mats |
| |
| | 18. Flower bract deciduous, tawny, sparsely to moderately hairy |
| |
| | 19. Tree, not clonal by root-sprouting; margins of bud scale free and overlapping; leaf margins entire to finely serrate; petiole glands present; stigmas persistent |
| 2 S. gooddingii |
| | 19' Slender shrub, clonal by root-sprouting; margins of bud scale fused; leaf margins entire or finely dentate with well separated teeth; petiole glands 0; stigmas deciduous after flower |
| |
| | 20. Leaf blade linear (length 10–23 × width); ovary silky or soft-shaggy-hairy; style 0–0.2 mm; outer nectary present |
| 2 S. exigua |
| | 20' Leaf blade narrowly elliptic, narrowly obovate or elliptic (length 3–8.5 × width); ovary densely long-soft-wavy-hairy; style 0.2–0.4 mm; outer nectary 0 |
| S. sessilifolia |
| | 18' Flower bract persistent, brown or tawny, generally moderately hairy |
| |
| | 21. Catkins appearing with the leaves, on distinct, leafy shoot |
| |
| | 22. Leaf blade not glaucous below or surface obscured by hair |
| |
| | 23. Leaf blade densely silky or silky-woolly below, dark green and sparsely silky (but becoming glabrous) above; twigs generally brittle at base |
| |
| | 24. Leaf blade 8–25 mm wide, length 3–7.3 × width, margins flat or slightly rolled under; nectary 0.3–0.6 mm; twigs highly brittle at base; High Cascade Range, High Sierra Nevada; 1000–3400 m |
| 3 S. jepsonii |
| | 24' Leaf blade 17–40 mm wide, length 2–4 × width, margins strongly rolled under; nectary 0.6–0.8 mm; twigs flexible or somewhat brittle at base; Northwestern California, Central Coast, San Francisco Bay Area, Outer South Coast Ranges, w Western Transverse Ranges; 0–400 m (except 1800– |
| |
| | 2500 m in n Northwestern California) |
| 4 S. sitchensis |
| | 23' Leaf blade sparsely to densely tomentose or silky and gray-green on both surfaces; twigs flexible at base |
| |
| | 25. Leaves on catkin shoots (and first leaves on vegetative twigs) distinctly finely serrate with long teeth |
| 3 S. eastwoodiae |
| | 25' Leaves on catkin shoots (and first leaves on vegetative twigs) entire or gland-dotted |
| |
| | 26. Leaf blade sparsely to moderately woolly-tomentose or silky, becoming glabrous below |
| |
| | 27. Leaf blade shaggy-(sometimes appressed)-hairy below, base rounded or cordate (rarely acute); nectary 0.5–0.8 mm; High Sierra Nevada, Klamath Ranges, High Cascade Range |
| 3 S. eastwoodiae |
| | 27' Leaf blade silky below, base acute; nectary 0.8–1 mm; High Sierra Nevada |
| 2 S. orestera |
| | 26' Leaf blade densely silky to woolly below |
| |
| | 28. Leaf blade 8–25 mm wide, length 3–7.3 × width, margins flat or slightly rolled under; nectary 0.3–0.6 mm; twigs highly brittle at base; High Cascade Range, High Sierra Nevada; 1000–3400 m |
| 3 S. jepsonii |
| | 28' Leaf blade 17–40 mm wide, length 2–4 × width, margins strongly rolled under; nectary 0.6– 0.8 mm; twigs flexible or somewhat brittle at base; Northwestern California, Central Coast, San Francisco Bay Area, Outer South Coast Ranges, w Western Transverse Ranges; 0–400 m (except 1800–2500 m in n Northwestern California) |
| 4 S. sitchensis |
| | 22' Leaf blade glaucous below |
| |
| | 29. Ovary on stalk 0–0.3 mm; subalpine shrub 0.2–0.5 m |
| S. brachycarpa subsp. brachycarpa |
| | 29' Ovary on stalk 0.4–5 mm; alpine, subalpine, or montane shrub or tree > 0.5 m |
| |
| | 30. Young leaves with rusty or white and rusty hairs |
| |
| | 31. Catkin subspheric, 9–20 mm; style 0.1–0.4 mm; fruit 4–5.2 mm; flower bract pale; leaves generally persistently silky on both surfaces; petioles 3–9 mm; stipules 0 or vestigial |
| 4 S. geyeriana |
| | 31' Catkin cylindric, 14–50 mm; style 0.3–0.8 mm; fruit 5–6 mm; flower bract dark; leaves silky (but becoming glabrous) on both surfaces; petiole 5–16 mm; stipules leaf-like (except vestigial on early leaves) |
| 2 S. lemmonii |
| | 30' Young leaves with white hairs |
| |
| | 32. Style 0.1–0.4 mm; ovary on stalk 1–5 mm |
| |
| | 33. Catkin 25–60 mm; twigs shaggy, not glaucous; petiole puberulent; leaf blade dull above; stipules leaf-like; ovary hairs gray, stalk 2–5 mm; 1000–1400 m |
| 2 S. bebbiana |
| | 33' Catkin 9–15 mm; twigs tomentose or velvety, generally glaucous; petiole velvety; leaf blade shiny above; stipules vestigial; ovary hairs white or white and rusty, stalk 1–2.8 mm; 1500–3600 m |
| 4 S. geyeriana |
| | 32' Style 0.4–1 mm; ovary on stalk 0.4–2 mm |
| |
| | 34. Style 0.4–0.6 mm; ovary short-silky; twigs highly brittle at base; leaf blade densely silky below; petiole silky or velvety |
| 3 S. jepsonii |
| | 34' Style 0.6–1 mm; ovary long-silky; twigs flexible at base; leaf blade sparsely to moderately silky below; petiole tomentose |
| 2 S. orestera |
| | 21' Catkins appearing before (sometimes just before) the leaves, sessile or subtended by greenish bracts |
| |
| | 35. Flower bract tawny or light rose |
| |
| | 36. Flower bract sparsely hairy; ovary sparsely or moderately silky, long-beaked; style 0.1–0.4 mm |
| |
| | 37. Catkin 25–60 mm; twigs shaggy, not glaucous; petiole puberulent; leaf blade dull above; stipules leaf-like; ovary hairs gray, stalk 2–5 mm; 1000–1400 m |
| 2 S. bebbiana |
| | 37' Catkin 9–15 mm; twigs tomentose or velvety, generally glaucous; petiole velvety; leaf blade shiny above; stipules vestigial; ovary hairs white or white and rusty, stalk 1–2.8 mm; 1500–3600 m |
| 4 S. geyeriana |
| | 36' Flower bract moderately to densely hairy; ovary densely hairy, short-beaked; style 0.4–0.8 mm |
| |
| | 38. Ovary tomentose, stalk 0–0.4 mm; nectary generally thread-like; leaf margins slightly rolled under, blade sparsely or moderately tomentose below; stipule tip rounded; on serpentine |
| S. breweri |
| | 38' Ovary silky, stalk 0.4–1.2 mm; nectary short, rod-like; leaf margins strongly rolled under, blade very densely woolly or silky below; stipule tip acute; not on serpentine |
| 4 S. sitchensis |
| | 35' Flower bract brown, black, or 2-colored |
| |
| | 39. Twigs strongly glaucous |
| S. drummondiana |
| | 39' Twigs not glaucous or weakly so |
| |
| | 40. Young leaves with white hairs |
| |
| | 41. Catkin stout; ovary stalk 1–2 mm |
| 3 S. hookeriana |
| | 41' Catkin slender; ovary stalk 0–1.2 mm |
| |
| | 42. Catkin 15–40 mm; ovary stalk 0–0.3 mm; leaf blade densely tomentose below; on serpentine, Klamath Ranges |
| S. delnortensis |
| | 42' Catkin 40–95 mm; ovary stalk 0.4–1.2 mm; leaf blade woolly or silky below; Northwestern California, Central Western California (except Inner South Coast Ranges), w Western Transverse Ranges |
| S. sitchensis |
| | 40' Young leaves with white or white and rusty hairs |
| |
| | 43. Stigma 0.2–0.4 mm; catkin < 45 mm |
| |
| | 44. Catkin 9–15 mm; style 0.1–0.4 mm; fruit 4–5.2 mm |
| 4 S. geyeriana |
| | 44' Catkin 13–50 mm; style 0.3–0.8 mm; fruit 5–6 mm |
| 2 S. lemmonii |
| | 43' Stigma 0.5–1.2 mm; catkin 30–140 mm in S. hookeriana, 10–45 mm in S. planifolia, 15–65 mm in S. scouleriana |
| |
| | 45. Young leaves sparsely hairy; ovary stalk 0.3–0.8 mm; fruit < 6 mm |
| S. planifolia subsp. planifolia |
| | 45' Young leaves densely hairy; ovary stalk 0.8–2.3 mm; fruit > 6 mm |
| |
| | 46. Style 0.6–1.4 mm; stigma 0.5–0.7 mm |
| 3 S. hookeriana |
| | 46' Style 0.3–0.6 mm; stigma 0.7–1.2 mm, slender |
| S. scouleriana
|
| | 1. Stamens > 2 per flower |
| |
| | 2. Margins of bud scale fused; anthers 0.7–1 mm |
| S. lucida |
| | 2' Margins of bud scale free and overlapping; anthers 0.4–0.6 mm |
| |
| | 3. Leaf blade not glaucous below; twigs yellowish or yellow-gray; margins of leaves on catkin shoots finely serrate; young leaf hairs white |
| S. gooddingii |
| | 3' Leaf blade glaucous below; twigs yellow- or red-brown; margins of leaves on catkin shoots entire; young leaf hairs white or white and rusty |
| S. laevigata |
| | 1' Stamens 1 or 2 per flower |
| |
| |
| | 5. Leaf blade 8–25 mm wide, length 3–7.3 × width; flower bract sparsely hairy; filaments hairy; twigs highly brittle at base; High Cascade Range, High Sierra Nevada; 1000–3400 m |
| 2 S. jepsonii |
| | 5' Leaf blade 17–40 mm wide, length 2–4 × width; flower bract moderately hairy; filaments glabrous; twigs flexible or somewhat brittle at base; Northwestern California, Central Coast, San Francisco Bay Area, Outer South Coast Ranges, w Western Transverse Ranges; 0–400 m (except 1800–2500 m in n Northwestern California) |
| S. sitchensis |
| |
| | 6. Dwarf alpine shrub, < 0.2 m, forming mats by rhizomes or adventitious rooting of stems |
| |
| | 7. Catkin on leafy shoot 9–18 mm; flower bract hairy; young leaves long-soft-wavy-hairy; only axillary nectary present |
| S. arctica |
| | 7' Catkin on leafy shoot 2.1–4 mm; flower bract glabrous; young leaves glabrous; both axillary and outer nectary present |
| S. reticulata subsp. nivalis |
| | 6' Low to tall shrub or tree, > 0.2 m, not mat-forming |
| |
| | 8. Both axillary and outer nectary present; catkins appearing with or after leaves, on leafy shoots; alien or native |
| |
| | 9. Tree; twigs brittle at base; alien |
| |
| | 10. Twigs erect or weakly pendent, generally yellow, sometimes gray- or red-brown; nectaries 2; twigs and young leaves densely silky |
| S. alba |
| | 10' Twigs pendent ± to ground, gray- to yellow-brown; nectaries 1–several; twigs and young leaves glabrous or sparsely silky |
| S. babylonica |
| | 9' Shrub; twigs flexible at base; native |
| |
| | 11. Low subalpine shrub, 0.2–0.5 m, not clonal by root-sprouting; catkin 4–5 mm on leafy shoot ± 1 mm; anthers 0.3–0.4 mm |
| S. brachycarpa subsp. brachycarpa |
| | 11' Medium or tall riparian shrub, 0.8–7 m, clonal by root-sprouting; catkin 20–70 mm on leafy shoot 5–110 mm; anthers 0.5 to 1.2 mm |
| |
| | 12. Leaf blade linear; young leaves silky |
| S. exigua |
| | 12' Leaf blade narrowly elliptic to narrowly obovate; young leaves silky or long-soft-wavy-hairy |
| |
| | 13. Petiole tomentose or becoming glabrous; flower bract glabrous to sparsely hairy; leaf blade becoming glabrous or sparsely to moderately tomentose below, tip acute; twigs gray-brown |
| S. melanopsis |
| | 13' Petiole silky; flower bract moderately hairy; leaf blade sparsely to very densely silky (or long-soft-wavy-hairy below), tip acuminate; twigs red-brown |
| S. sessilifolia |
| | 8' Only axillary nectary present; catkins appearing before or with leaves, sessile or on leafy shoots; native |
| |
| | 14. Catkins appearing with leaves, on distinct, leafy shoots |
| |
| | 15. Hairs of young leaves rusty (or white and rusty) |
| |
| | 16. Catkin 6–12 mm; flower bract tawny to light brown; anthers 0.4–0.5 mm |
| 4 S. geyeriana |
| | 16' Catkin 13–35 mm; flower bract brown to 2-colored; anthers 0.5–0.9 mm |
| 2 S. lemmonii |
| | 15' Hairs of young leaves white only |
| |
| |
| | 18. Leaf blade not glaucous below; leaves on catkin shoots finely serrate with long teeth (rarely only gland-dotted) |
| 2 S. eastwoodiae |
| | 18' Leaf blade glaucous below or surface obscured by hair; leaves on catkin shoots entire or gland-dotted |
| |
| | 19. Stipules 0 or vestigial |
| |
| | 20. Catkin 9–15 mm; anthers 0.4–0.5 mm; leaf blade shiny above; petiole velvety |
| 4 S. geyeriana |
| | 20' Catkin 12–25 mm; anthers 0.6–1 mm; leaf blade dull above; petiole tomentose |
| 2 S. orestera |
| |
| | 21. Leaf blade densely silky below; petiole silky or velvety; twigs very brittle at base |
| 2 S. jepsonii |
| | 21' Leaf blade sparsely to moderately tomentose or silky below; petiole puberulent or tomentose; twigs flexible at base |
| |
| | 22. Flower bract tawny; twigs moderately to densely long-soft-wavy-hairy; petiole puberulent; 1200–1400 m |
| 2 S. bebbiana |
| | 22' Flower bract brown; twigs sparsely soft-shaggy-hairy or silky, becoming glabrous; petiole tomentose; 2100–4000 m |
| 2 S. orestera |
| |
| | 23. Stipules 0 or vestigial, stipule scars 0 or minute |
| 4 S. geyeriana |
| | 23' Stipules leaf-like, stipule scars distinct |
| |
| | 24. Leaf blade not glaucous below |
| 2 S. eastwoodiae |
| | 24' Leaf blade glaucous below |
| |
| | 25. Twigs yellowish to yellow-gray, not peeling; anthers 0.7–1.2 mm |
| S. lutea |
| | 25' Twigs generally red-brown sometimes yellow-brown, peeling; anthers 0.5–0.8 mm |
| |
| | 26. Leaf blade margin entire to crenate; flower bract 1.2–3.2 mm, hairs wavy |
| 2 S. bebbiana |
| | 26' Leaf blade generally serrate; flower bract 0.8–1.6 mm, hairs curly |
| |
| | 27. Leaf blade lanceolate to elliptic, base acute to rounded; stipule tip acute |
| S. ligulifolia |
| | 27' Leaf blade lanceolate to ovate, base generally cordate; stipule tip rounded |
| S. prolixa |
| | 14' Catkins appearing before leaves, sessile or subtended by greenish bracts |
| |
| | 28. Flower bracts generally tawny |
| |
| | 29. Catkin 20–32 mm; flower bracts densely hairy; twigs not glaucous; hairs of young leaves white only; on serpentine; 300–1300 m |
| S. breweri |
| | 29' Catkin 6–12 mm; flower bracts sparsely hairy; twigs generally glaucous; hairs of young leaves generally white and rusty; not on serpentine; 1500–3600 m |
| 4 S. geyeriana |
| | 28' Flower bracts generally dark brown to blackish |
| |
| | 30. Twigs densely glaucous |
| S. drummondiana |
| | 30' Twigs not glaucous (or thinly so) |
| |
| | 31. Twigs generally glabrous or becoming so |
| |
| | 32. Nectary short, square |
| 2 S. scouleriana |
| | 32' Nectary distinctly rod-like |
| |
| | 33. Young leaves generally glabrous |
| S. planifolia subsp. planifolia |
| | 33' Young leaves generally densely hairy |
| |
| | 34. Flower bracts widest at widely rounded tip, generally densely hairy; 0–2800 m |
| 2 S. lasiolepis |
| | 34' Flower bracts widest at middle, sparsely to moderately hairy; 1450–3500 m |
| 2 S. lemmonii |
| | 31' Twigs generally persistently (sometimes densely) hairy |
| |
| | 35. Anthers 0.4–0.6 mm; flower bracts generally obscured by hairs |
| 2 S. lasiolepis |
| | 35' Anthers 0.6–1.2 mm; flower bracts sparsely to moderately hairy |
| |
| | 36. Twigs brittle at base; on serpentine |
| S. delnortensis |
| | 36' Twigs brittle or flexible at base; not on serpentine |
| |
| | 37. Catkins 30–60 mm, stout; twigs brittle at base; coastal dunes and meadows, generally < 100 m |
| S. hookeriana |
| | 37' Catkins 15–45 mm, slender; twigs flexible at base; upland forest to subalpine meadows, 90–3400 m |
| |
| | 38. Nectary rod-like; leaves on catkin shoots gland-dotted or finely serrate; subalpine meadows, lake- and stream-shores, 1700–3200 m |
| S. boothii |
| | 38' Nectary square; leaves on catkin shoots entire; upland forests, meadows, 90–3400 m |
| 2 S. scouleriana
|