Ceanothus thyrsiflorus |
Ceanothus prostratus |
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blue blossom, blue blossom ceanothus |
mahala mat, prostrate ceanothus, squawcarpet |
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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, 0.1–0.3 m, matlike to moundlike. | ||||
Stems | prostrate, spreading, or ascending, rooting at distal nodes; branchlets reddish brown, ± flexible, puberulent, glabrescent. |
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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, crowded, usually longer than internodes and obscuring them; petiole 1–3 mm; blade flat to ± cupped, elliptic to obovate, 6–30 × 4–16 mm, base cuneate, margins sometimes thick, not revolute, sometimes wavy, sharply dentate to spinose-dentate, teeth 3–9, apex rounded, abaxial surface pale green, glabrous except sparsely strigillose on veins, adaxial surface dark green, shiny, glabrate. |
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Inflorescences | terminal, usually racemelike, rarely paniclelike, 2.5–9 cm. |
axillary, 0.9–2 cm. |
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Flowers | sepals, petals, and nectary usually pale to deep blue, rarely white. |
sepals, petals, and nectary pale to deep blue or purplish blue. |
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Capsules | 3–4 mm wide, weakly lobed; valves smooth, viscid, not crested. |
6–9 mm wide, lobed; valves smooth to rugulose, horns subapical, prominent, erect or spreading, rugose or not, intermediate ridges present. |
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2n | = 24. |
= 24. |
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Ceanothus thyrsiflorus |
Ceanothus prostratus |
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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; ID; NV; OR; WA
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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 2 (2 in the flora). Putative hybrids between Ceanothus prostratus and C. velutinus var. velutinus, named C. ×rugosus, have been reported from northeastern California (H. McMinn 1944). A rare putative hybrid between C. prostratus and C. cordulatus in the Lake Tahoe basin has been named C. ×serrulatus. Both C. ×rugosus and C. ×serrulatus are intersubgeneric hybrids. Formally named hybrids between C. prostratus and C. cuneatus var. cuneatus include C. ×flexilis and possibly C. ×connivens, but the latter could have C. fresnensis as one of the parents rather than C. prostratus. (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. 104. | ||||
Parent taxa | Rhamnaceae > Ceanothus > subg. Ceanothus | Rhamnaceae > Ceanothus > subg. Cerastes | ||||
Sibling taxa | ||||||
Subordinate 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) | Bentham: Pl. Hartw., 302. (1849) | ||||
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