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,
4. Flowers white with blue tinge, pale blue, lavender, deep blue to purple.
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
5. Leaves abaxially not densely white tomentose, usually microscopically canescent, usually not revolute.
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
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
7. Horns conspicuous, apical or subapical
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
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,
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
11. Shrubs ascending to erect, usually not rooting along the branches.
12. Leaves holly-like, spinescent.
11. Shrubs prostrate, decumbent or sprawling, usually rooting along the branches.
13. Leaf margins somewhat revolute.
12 Leaves entire or if toothed, not holly-like, not spinescent
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
13. Leaf margins not revolute.
14. Blades with 5--8 spiny teeth, bases cuneate, tips +/-
truncate, abaxially grayish, adaxially green, plane ; flowers
pentamerous, deep blue to purple. - C.
15. Leaves 0.8--1.5 long, plane, tips notched. -
15. Leaves 1.3--2.5, +/- troughed, tips obtuse. -
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.
16. Leaf margins continuously toothed.
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.
17. Leaves not clustered; twigs tomentose.
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
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
20. Twigs flexible; leaves 1.5--4.0 cm long;
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
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
22. Leaves not dull green adaxially; twigs usually glabrous.
23. Leaves not clustered, margins not revolute, adaxially
glabrous; flowers white with blue tinge; fruit horns stubby,
lateral, or 0. - C. rockerickii
24. Leaf blades tending to be nearly round, or broadly elliptic to broadly oblong.
25. Leaf margins entire; flowers lavender;
Barbara Co., Point Sal. - C. cuneatus
24. Leaves blades narrowly to broadly obovate or oblong, clearly longer than wide.
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. -
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
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