Ceanothus thyrsiflorus |
Ceanothus cuneatus |
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blue blossom, blue blossom ceanothus |
buck brush, common buckbrush, narrow-leaf buckthorn, sedge-leaf buckthorn, wedgeleaf cuneatus |
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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, 0.5–3.5 m. Stems erect, ascending, or spreading, not rooting at nodes; branchlets grayish brown to brown, rigid or flexible, glabrate, puberulent, or tomentulose, hairs straight. | ||||||||||||
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. |
usually both fascicled and not fascicled on same plant, rarely none fascicled; petiole 1–3 mm; blade flat to cupped, elliptic, oblanceolate, obovate, or orbiculate, 4–22(–30) × 3–12(–22) mm, base rounded, margins thick, not revolute, entire or denticulate distal to middle, teeth 0–9, apex obtuse, rounded, truncate, or retuse, abaxial surface pale green, glabrate or glabrous, adaxial surface green, glabrous. |
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Inflorescences | terminal, usually racemelike, rarely paniclelike, 2.5–9 cm. |
axillary or terminal, 0.8–2.5 cm. |
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Flowers | sepals, petals, and nectary usually pale to deep blue, rarely white. |
sepals, petals, and nectary white to lavender or blue. |
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Capsules | 3–4 mm wide, weakly lobed; valves smooth, viscid, not crested. |
4–6 mm wide, weakly lobed; valves smooth, horns subapical, prominent, erect, intermediate ridges absent. |
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2n | = 24. |
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Ceanothus thyrsiflorus |
Ceanothus cuneatus |
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Phenology | Flowering Mar–Jun. | |||||||||||||
Habitat | Sandy or rocky flats and slopes, maritime chaparral, open sites in mixed evergreen and conifer forests. | |||||||||||||
Elevation | 10–600 m. (0–2000 ft.) | |||||||||||||
Distribution |
CA; OR; Mexico (Baja California)
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CA; OR; nw Mexico
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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.) |
Varieties 4 (4 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 90. | FNA vol. 12, p. 99. | ||||||||||||
Parent taxa | Rhamnaceae > Ceanothus > subg. Ceanothus | Rhamnaceae > Ceanothus > subg. Cerastes | ||||||||||||
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Synonyms | C. thyrsiflorus var. chandleri, C. thyrsiflorus var. repens | Rhamnus cuneata | ||||||||||||
Name authority | Eschscholtz: Mém. Acad. Imp. Sci. St. Pétersbourg Hist. Acad. 10: 285. (1826) — (as thyrsiflora) | (Hooker) Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 267. (1838) | ||||||||||||
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