Flora of North America species comparison

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Ceanothus cordulatus

Ceanothus verrucosus

mountain whitethorn, snow bush, whitethorn ceanothus

barranca brush, wart-stem ceanothus, white coast ceanothus
Habit Shrubs, evergreen, 0.5–1.5 m. Shrubs, 1–3 m.
Stems

ascending to spreading, not rooting at nodes;

branchlets yellowish or grayish green, glaucescent, thorn-tipped, round in cross section, rigid, puberulent, glabrescent.

erect to ascending, not rooting at nodes;

branchlets grayish brown, rigid, tomentulose.
Leaves

petiole 2–8 mm;

blade flat to cupped, ovate to elliptic, 10–30 × 6–18 mm, base rounded, margins usually entire, sometimes minutely glandular-denticulate distally, glands 18–30, apex obtuse, abaxial surface pale grayish green, sparsely puberulent or glabrous, sometimes villosulous along veins, adaxial surface pale green to grayish green, glaucous, dull, glabrate; 3-veined from base.

alternate, not fascicled, often crowded;

petiole 1–3 mm;

blade flat to cupped, widely obovate to suborbiculate, 5–14 × 3–10 mm, base cuneate to rounded, margins not revolute, entire to weakly denticulate distal to middle, teeth 9–16, apex truncate to retuse, abaxial surface pale green, sparsely strigillose, glabrescent, adaxial surface dark green, glabrous.
Inflorescences

axillary, umbel-like or racemelike, sometimes densely clustered, 1.2–2(–4) cm.

axillary, 1–1.5 cm.
Flowers

sepals, petals, and nectary usually white, rarely pink.

sepals and petals white;

nectary black.
Capsules

3.5–5 mm wide, lobed;

valves rugose, viscid when young, weakly crested.

4–6 mm wide, weakly lobed;

valves smooth, horns minute or absent, intermediate ridges absent.
2n

= 24.

= 24.

Ceanothus cordulatus

Ceanothus verrucosus
Phenology Flowering May–Jul. Flowering Jan–Apr.
Habitat Rocky ridges and slopes, chaparral, conifer and mixed evergreen forests. Slopes, coastal mesas, chaparral, pine woodlands.
Elevation 400–3400 m. [1300–11200 ft.] 20–800 m. [70–2600 ft.]
Distribution
from FNA
CA; NV; OR; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
Discussion

Ceanothus cordulatus is one of the most common shrubs in montane chaparral and forests of the Coast Ranges and Cascades of southern Oregon and northern California, southward through the Sierra Nevada, Transverse and Peninsular ranges of California, to the mountains of northern Baja California, and occurs disjunctly in the Charleston Mountains of Nevada.

Putative hybrids between Ceanothus cordulatus and C. velutinus var. velutinus, reported from the Klamath Mountains, the southern Cascade Range, and the Sierra Nevada, have been called C. ×lorenzenii (Jepson) McMinn. A rare intersectional hybrid between C. cordulatus and C. prostratus in the Lake Tahoe basin has been named C. ×serrulatus McMinn. Putative hybrids of C. cordulatus with C. diversifolius and C. integerrimus also have been reported (H. McMinn 1944).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Ceanothus verrucosus occurs from San Diego County to the foothills of the Sierra San Pedro Mártir and Cedros Island in northern Baja California, Mexico; its habitat is threatened by development and urbanization throughout its range.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 87. FNA vol. 12, p. 97.
Parent taxa Rhamnaceae > Ceanothus > subg. Ceanothus Rhamnaceae > Ceanothus > subg. Cerastes
Sibling taxa
C. americanus, C. arboreus, C. arcuatus, C. confusus, C. crassifolius, C. cuneatus, C. cyaneus, C. dentatus, C. divergens, C. diversifolius, C. fendleri, C. ferrisiae, C. foliosus, C. fresnensis, C. gloriosus, C. griseus, C. hearstiorum, C. herbaceus, C. impressus, C. incanus, C. integerrimus, C. jepsonii, C. lemmonii, C. leucodermis, C. maritimus, C. martini, C. masonii, C. megacarpus, C. microphyllus, C. oliganthus, C. ophiochilus, C. otayensis, C. palmeri, C. papillosus, C. parryi, C. parvifolius, C. pauciflorus, C. perplexans, C. pinetorum, C. prostratus, C. pumilus, C. purpureus, C. roderickii, C. sanguineus, C. sonomensis, C. spinosus, C. thyrsiflorus, C. tomentosus, C. velutinus, C. verrucosus
C. americanus, C. arboreus, C. arcuatus, C. confusus, C. cordulatus, C. crassifolius, C. cuneatus, C. cyaneus, C. dentatus, C. divergens, C. diversifolius, C. fendleri, C. ferrisiae, C. foliosus, C. fresnensis, C. gloriosus, C. griseus, C. hearstiorum, C. herbaceus, C. impressus, C. incanus, C. integerrimus, C. jepsonii, C. lemmonii, C. leucodermis, C. maritimus, C. martini, C. masonii, C. megacarpus, C. microphyllus, C. oliganthus, C. ophiochilus, C. otayensis, C. palmeri, C. papillosus, C. parryi, C. parvifolius, C. pauciflorus, C. perplexans, C. pinetorum, C. prostratus, C. pumilus, C. purpureus, C. roderickii, C. sanguineus, C. sonomensis, C. spinosus, C. thyrsiflorus, C. tomentosus, C. velutinus
Name authority Kellogg: Proc. Calif. Acad. Sci. 2: 124, fig. 39. (1863) Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 267. (1838)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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