Flora of North America species comparison

The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Ceanothus cordulatus

Ceanothus palmeri

mountain whitethorn, snow bush, whitethorn ceanothus

Palmer ceanothus, Palmer's ceanothus
Habit Shrubs, evergreen, 0.5–1.5 m. Stems ascending to spreading, not rooting at nodes; branchlets yellowish or grayish green, glaucescent, thorn-tipped, round in cross section, rigid, puberulent, glabrescent. Shrubs, evergreen or semideciduous, 1–2 m. Stems ascending to erect, not rooting at nodes; branchlets green or gray-green, not thorn-tipped, round in cross section, flexible or rigid, glabrous or glabrate.
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.

not fascicled;

petiole 3–8 mm;

blade ± cupped, elliptic, oblong, or oblong-ovate, 13–30 × 9–15 mm, base cuneate to obtuse, margins entire, apex acute to rounded, abaxial surface pale green, glabrous, adaxial surface green, dull to ± shiny, glabrous; usually pinnately veined, rarely 3-veined.
Inflorescences

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

terminal or axillary, paniclelike, 7.5–22 cm.
Flowers

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

sepals, petals, and nectary usually white, rarely pale blue.
Capsules

3.5–5 mm wide, lobed;

valves rugose, viscid when young, weakly crested.

4.5–7 mm wide, lobed;

valves smooth, viscid, crested.
2n

= 24.

Ceanothus cordulatus

Ceanothus palmeri
Phenology Flowering May–Jul. Flowering Mar–Jun.
Habitat Rocky ridges and slopes, chaparral, conifer and mixed evergreen forests. Rocky slopes, chaparral, conifer forests.
Elevation 400–3400 m. (1300–11200 ft.) 1100–1800 m. (3600–5900 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 palmeri occurs in the Transverse and Peninsular ranges of California, with a disjunct distribution in the central Sierra Nevada foothills (Amador and El Dorado counties). Ceanothus palmeri appears to be closely related to and intermediate between C. integerrimus and C. spinosus (W. L. Jepson 1909–1943, vol. 2; M. Van Rensselaer and H. McMinn 1942). We treat this species as distinct from C. spinosus on the basis of its white flowers, and viscid, lobed fruit, but note that some populations intergrade, especially in the Transverse Ranges of southern California. Leaf blades of both C. palmeri and C. spinosus have somewhat shiny adaxial faces, but those of C. integerrimus appear dull. Included here are plants with weakly three-veined leaf blades with somewhat shiny adaxial surfaces from the Transverse Ranges, previously treated by Van Rensselaer and McMinn as part of C. integerrimus.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 87. FNA vol. 12, p. 86.
Parent taxa Rhamnaceae > Ceanothus > subg. Ceanothus Rhamnaceae > Ceanothus > subg. Ceanothus
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. 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
Synonyms C. spinosus var. palmeri
Name authority Kellogg: Proc. Calif. Acad. Sci. 2: 124, fig. 39. (1863) Trelease: Proc. Calif. Acad. Sci., ser. 2, 1: 109. (1888)
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).



Type/paste one or more Latin names into the boxes above; matching taxa will show up below the box as you type. You can use the up/down arrow keys to move through the list.

(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Fabaceae, Apiaceae, Boraginaceae, and Polemoniaceae.)

Choose a data source: Flora of North America, OregonFlora

The species comparison tool is brought to you by:
Northwest Wildflowers