Full text key to N. American species of Ceanothus

Key to Subgenus Cerastes

Full key to subgenus: Ceanothus

Ceanothus subg. Cerastes Weberbauer Nat. Pflanzenfam. 3(5): 414 (check page#). 1896

Ceanothus sect. Cerastes S. Watson Proc. Am. Acad. Arts Sci., 10, 338. 1875 Weberbauer Nat. Pflanzenfam. 3(5): 413--414. 1896 also recognized sect. rigidi (Rigidae). Apparently valid.

Key to the species of Ceanothus subg. Cerastes

1. Leaves alternate or alternate and opposite.
2. Leaves all alternate; twigs roughened, rigid; fruits 5 mm broad. - C. verrucosus
2. Leaves alternate and/or opposite; twigs smooth, flexible; fruits more than 8 mm broad.
3. Leaves alternate, sometimes opposite; petioles 2--3 mm; blades 1.0--2.5 cm; fruits 8-12 mm broad, sticky, horns lateral or dorsal - C. megacarpus
3. Leaves opposite, sometimes alternate; petioles 5--7 mm; blades 1.9--3.5 cm; fruits 8-10 mm broad, smooth, horns usually 0, or minute and lateral. - C. insularis

1. Leaves opposite.
4. Flowers usually white or whitish.
5. Leaves abaxially densely white tomentose, usually revolute.
6. Shrubs more than 1.5 m; leaf petioles 2--6 mm, blades broadly elliptic or elliptic-obovate 1.5--3.0 cm long; fruits 6--8 mm broad, horns prominent. - C. crassifolius
6. Shrubs less than 1.3 m; leaf petioles 0--2 mm, blades broadly oval, 0.5--1.3 cm long; fruits 5 mm broad, horns minute or 0; Calif., Otay Mountain, San Diego Co. s. into n. Baja California, Mexico - C. otayensis
5. Leaves abaxially not densely white tomentose, usually microscopically canescent, usually not revolute.
7. Horns minute, usually lateral or 0;
8. Fruit 3--5 mm broad; inflorescences to 3 cm, flowers white or cream; leaf blades to 2.0 cm, adaxial surface may be concave, petioles to 3 mm. - C. greggii
8. Fruit 8--10 mm broad; inflorescences to 1.3 cm, flowers white or with dark centers; leaf blades to 3.5 cm, plane, petioles 5--7 mm.- C. insularis
7. Horns conspicuous, apical or subapical
9. Leaves entire, plane, bases cuneate; fruit 5--6 mm broad. - C. cuneatus
9. Leaves toothed or entire, +/- troughed; bases round; fruit 6--9 mm broad.
10. Leaves toothed towards tip or entire, adaxially dark green; fruits 7--9 mm broad; flowers pentamerous. - C. ferrisae
10. Leaves continuously spiny toothed, adaxially yellow-green; fruits 6 mm broad; flowers hexamerous to octamerous. - C. jepsonii var. albiflorus
4. Flowers white with blue tinge, pale blue, lavender, deep blue to purple.
11. Shrubs ascending to erect, usually not rooting along the branches.
12. Leaves holly-like, spinescent.
13. Leaf margins somewhat revolute.
14. Blades with 8--10 spiny teeth, bases round, tips round, adaxially yellow-green, troughed; flowers hexamerous to octamerous, pale blue to lavender. - C. jepsonii var. jepsonii
14. Blades with 5--8 spiny teeth, bases cuneate, tips +/- truncate, abaxially grayish, adaxially green, plane ; flowers pentamerous, deep blue to purple. - C. divergens
13. Leaf margins not revolute.
15. Leaves 0.8--1.5 long, plane, tips notched. - C. sonomensis
15. Leaves 1.3--2.5, +/- troughed, tips obtuse. - C. purpureus
12 Leaves entire or if toothed, not holly-like, not spinescent
16. Leaf margins entire or toothed towards apex
17. Leaves clustered, plane or shallowly troughed; twigs glabrous; flowers pale blue, pinkish lavender or +/- white; fruit horns minute or 0.
18. Leaves 0.5--2.0 cm long, adaxially dull green, plane; fruits 4--5 mm broad; flowers lavender, pale blue to +/- white. - C. cuneatus var. fascicularis
18. Leaves 3.5--7.0 cm long, adaxially yellow- green, shallowly troughed; fruits 3--4 mm broad; flowers pale blue, rarely pinkish lavender. - C. ophiochilus
17. Leaves not clustered; twigs tomentose.
19. Leaves adaxially +/- concave; flowers light blue to bright blue; fruits 5 mm broad, horns minute; shrubs to 1.5 m. - C. cuneatus var rigidus
19. Leaves adaxially plane; flowers blue or fading blue; fruits 3--5 mm broad, smooth, horns minute or 0; shrubs 2-5 dm. - C. greggii var. franklinii
16. Leaf margins continuously toothed.
20. Twigs flexible; leaves 1.5--4.0 cm long; stems erect-arching; fruits deeply lobed, 3.5--4.5 mm broad, smooth; horns minute, valve crests 0. - C. gloriosus var. exaltatus
20. Twigs rigid; leaves 0.6--2.0 cm long.
21. Stems erect-spreading; Leaf margins with numerous, short teeth; fruits +/- 3.5 mm broad, smooth, horns minute, valve crests 0. - C. masonii
21. Stems semiprostrate to erect; leaf margins with 6--9 coarse teeth on a side; fruits 6--7 mm broad, horns prominent, valves crested. - C. pinetorum
11. Shrubs prostrate, decumbent or sprawling, usually rooting along the branches.
22. Leaves dull green adaxially, twigs pubescent.
23. Leaves somewhat clustered, margins rarely slightly revolute, adaxially puberulent; flowers blue; fruit horns slender, near apex. - C. fresnensis
23. Leaves not clustered, margins not revolute, adaxially glabrous; flowers white with blue tinge; fruit horns stubby, lateral, or 0. - C. rockerickii
22. Leaves not dull green adaxially; twigs usually glabrous.
24. Leaf blades tending to be nearly round, or broadly elliptic to broadly oblong.
25. Leaf margins entire; flowers lavender; Calif., Santa Barbara Co., Point Sal. - C. cuneatus var. cuneatus
25. Leaf margins dentate, teeth spine-like or not.
26. Flowers blue to purple; fruits 3.5-4.5 mm broad, horns minute, valve crests 0; Calif., Marin Co., coastal bluffs. - C. gloriosus
26. Flowers blue, pale blue varying to nearly white; fruits 6--7 mm broad, horns prominent, valves crested; Calif., Sierra Nevada Range (Kern Plateau), Klamath Range. - C. pinetorum
24. Leaves blades narrowly to broadly obovate or oblong, clearly longer than wide.
27. Leaf margins not revolute, usually 3-9-toothed above middle or at apex, 0.6--3.2 long, adaxially dark green, +/- glabrous, plane to slightly troughed; fruit valve crests prominent; shrubs prostrate. - C. prostratus
27. Leaf margins revolute, at least slightly; fruit valve crest 0 or minute; shrubs prostrate or decumbent to low spreading.
28. Leaves abaxially white wooly blade margins revolute, 2--6 toothed above middle, tips abruptly pointed, truncate, or notched, flowers light to deep blue. - C. maritimus
28. Leaves abaxially pale green, veins usually pubescent, canescent between veins, margins somewhat revolute.
29. Leaf margins usually entire except 3-toothed at truncate tip, adaxially sometimes slightly concave; flowers white to blue or lavender; fruit horns lateral, minute; valves crests 0 - C. pumilus
29. Leaf margins coarsely dentate, usually 3--5 sharp teeth above middle or at tip, adaxially plane; flowers light to deep blue, lavender, or purple; fruit horns dorsal, erect to spreading, slender, valve crests minute - C. confusus