Flora of North America species comparison

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Ceanothus thyrsiflorus

Ceanothus hearstiorum

blue blossom, blue blossom ceanothus

Hearst ceanothus, Hearst ranch buckbrush, Hearst's 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, 0.1–0.3 m, matlike or moundlike.
Stems

spreading or prostrate, not rooting at nodes, some flowering branches ascending;

branchlets green to reddish brown, not thorn-tipped, round or slightly angled in cross section, flexible, densely puberulent.
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 1–2 mm;

blade flat to cupped, linear, oblong, or oblong-obovate, 8–20 × 2–10 mm, base cuneate to obtuse, margins entire or obscurely glandular-denticulate, weakly revolute, glands 23–31, apex truncate or retuse, abaxial surface green, densely tomentulose, adaxial surface dark green, glandular-papillate and sometimes villosulous; pinnately veined, veins ± furrowed.
Inflorescences

terminal, usually racemelike, rarely paniclelike, 2.5–9 cm.

terminal or axillary, umbel-like or racemelike, 1–5 cm.
Flowers

sepals, petals, and nectary usually pale to deep blue, rarely white.

sepals, petals, and nectary deep blue.
Capsules

3–4 mm wide, weakly lobed;

valves smooth, viscid, not crested.

4–5 mm wide, not lobed to weakly lobed;

valves smooth, not crested.
2n

= 24.

Ceanothus thyrsiflorus

Ceanothus hearstiorum
Phenology Flowering Mar–Jun. Flowering Mar–Apr.
Habitat Sandy or rocky flats and slopes, maritime chaparral, open sites in mixed evergreen and conifer forests. Consolidated alluvial or serpentine soils, maritime chaparral, coastal prairies.
Elevation 10–600 m. (0–2000 ft.) 20–200 m. (100–700 ft.)
Distribution
from FNA
CA; OR; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
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 hearstiorum occurs in a small area of coastal bluffs in northern San Luis Obispo County, growing in close proximity to another local endemic, C. maritimus (subg. Cerastes).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 90. FNA vol. 12, p. 93.
Parent taxa Rhamnaceae > Ceanothus > subg. Ceanothus Rhamnaceae > Ceanothus > subg. Ceanothus
Sibling taxa
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. 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. 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. 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
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) Hoover & Roof: Four Seasons 2(1): 4. (1966)
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).



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