Ceanothus thyrsiflorus |
Ceanothus cordulatus |
|
---|---|---|
blue blossom, blue blossom ceanothus |
mountain whitethorn, snow bush, whitethorn ceanothus |
|
Habit | Shrubs, sometimes arborescent, evergreen, 0.5–6 m. Stems erect, usually ascending to arcuate, rarely prostrate, not rooting at nodes; branchlets green, not thorn-tipped, angled in cross section, flexible, not tuberculate, sparsely puberulent or glabrous. | 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. |
Leaves | petiole 3–10 mm; blade flat to cupped, elliptic to ovate, 10–40(–50) × 5–15(–20) mm, base obtuse to rounded, margins denticulate to serrulate, usually not revolute, sometimes incompletely revolute, teeth glandular, 23–48, apex obtuse, abaxial surface pale green, sparsely puberulent to villosulous or glabrate, veins prominently raised, puberulent to villosulous, adaxial surface dark green, glabrate; 3-veined from base. |
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. |
Inflorescences | terminal, usually racemelike, rarely paniclelike, 2.5–9 cm. |
axillary, umbel-like or racemelike, sometimes densely clustered, 1.2–2(–4) cm. |
Flowers | sepals, petals, and nectary usually pale to deep blue, rarely white. |
sepals, petals, and nectary usually white, rarely pink. |
Capsules | 3–4 mm wide, weakly lobed; valves smooth, viscid, not crested. |
3.5–5 mm wide, lobed; valves rugose, viscid when young, weakly crested. |
2n | = 24. |
= 24. |
Ceanothus thyrsiflorus |
Ceanothus cordulatus |
|
Phenology | Flowering Mar–Jun. | Flowering May–Jul. |
Habitat | Sandy or rocky flats and slopes, maritime chaparral, open sites in mixed evergreen and conifer forests. | Rocky ridges and slopes, chaparral, conifer and mixed evergreen forests. |
Elevation | 10–600 m. (0–2000 ft.) | 400–3400 m. (1300–11200 ft.) |
Distribution |
CA; OR; Mexico (Baja California)
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CA; NV; OR; Mexico (Baja California)
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Discussion | Ceanothus thyrsiflorus occurs along the coast from Coos County, Oregon, south to Santa Barbara County, California, and disjunctly near Eréndira, Baja California. A wide range of growth forms characterize this species and the closely related C. griseus, including plants ranging from almost prostrate to arborescent, sometimes with single trunks. Prostrate plants from several maritime bluffs along the California coast have been called C. thyrsiflorus var. repens McMinn; they retain their stature under cultivation. Named hybrids include C. ×regius (Jepson) McMinn (C. thyrsiflorus × C. papillosus) and C. ×vanrensselaeri Roof (C. thyrsiflorus × C. incanus). H. McMinn (1944) reported hybrids with C. foliosus. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 12, p. 90. | FNA vol. 12, p. 87. |
Parent taxa | Rhamnaceae > Ceanothus > subg. Ceanothus | Rhamnaceae > Ceanothus > subg. Ceanothus |
Sibling taxa | ||
Synonyms | C. thyrsiflorus var. chandleri, C. thyrsiflorus var. repens | |
Name authority | Eschscholtz: Mém. Acad. Imp. Sci. St. Pétersbourg Hist. Acad. 10: 285. (1826) — (as thyrsiflora) | Kellogg: Proc. Calif. Acad. Sci. 2: 124, fig. 39. (1863) |
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