Ceanothus thyrsiflorus |
Ceanothus palmeri |
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blue blossom, blue blossom ceanothus |
Palmer ceanothus, Palmer's ceanothus |
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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 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 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. |
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 | terminal, usually racemelike, rarely paniclelike, 2.5–9 cm. |
terminal or axillary, paniclelike, 7.5–22 cm. |
Flowers | sepals, petals, and nectary usually pale to deep blue, rarely white. |
sepals, petals, and nectary usually white, rarely pale blue. |
Capsules | 3–4 mm wide, weakly lobed; valves smooth, viscid, not crested. |
4.5–7 mm wide, lobed; valves smooth, viscid, crested. |
2n | = 24. |
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Ceanothus thyrsiflorus |
Ceanothus palmeri |
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Phenology | Flowering Mar–Jun. | Flowering Mar–Jun. |
Habitat | Sandy or rocky flats and slopes, maritime chaparral, open sites in mixed evergreen and conifer forests. | Rocky slopes, chaparral, conifer forests. |
Elevation | 10–600 m. (0–2000 ft.) | 1100–1800 m. (3600–5900 ft.) |
Distribution |
CA; OR; Mexico (Baja California)
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CA; 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 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. 90. | FNA vol. 12, p. 86. |
Parent taxa | Rhamnaceae > Ceanothus > subg. Ceanothus | Rhamnaceae > Ceanothus > subg. Ceanothus |
Sibling taxa | ||
Synonyms | C. thyrsiflorus var. chandleri, C. thyrsiflorus var. repens | C. spinosus var. palmeri |
Name authority | Eschscholtz: Mém. Acad. Imp. Sci. St. Pétersbourg Hist. Acad. 10: 285. (1826) — (as thyrsiflora) | Trelease: Proc. Calif. Acad. Sci., ser. 2, 1: 109. (1888) |
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