Flora of North America species comparison

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Ceanothus thyrsiflorus

Ceanothus ophiochilus

blue blossom, blue blossom ceanothus

Vail Lake 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, 1–2 m. Stems erect to ascending, not rooting at nodes; branchlets reddish brown to gray, terete, ± flexible to rigid, 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.

both fascicled and not fascicled on same plant;

petiole 0–1 mm;

blade folded lengthwise abaxially, narrowly oblanceolate to narrowly obovate, 3–7 × 1–3 mm, base cuneate, margins not revolute, usually entire, rarely denticulate near apex, teeth 1–4, apex obtuse, rounded, or cuspidate, abaxial surface pale green, glabrate, adaxial surface pale to yellowish green, glabrate.
Inflorescences

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

axillary or terminal, 0.7–2 cm.
Flowers

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

sepals, petals, and nectary pale blue or pink-tinged.
Capsules

3–4 mm wide, weakly lobed;

valves smooth, viscid, not crested.

3–4 mm wide, not lobed;

valves smooth, horns minute or absent, intermediate ridges absent.
2n

= 24.

Ceanothus thyrsiflorus

Ceanothus ophiochilus
Phenology Flowering Mar–Jun. Flowering Mar–Apr.
Habitat Sandy or rocky flats and slopes, maritime chaparral, open sites in mixed evergreen and conifer forests. Rocky soils from deeply weathered gabbro or pyroxene substrates, slopes and ridges, chaparral.
Elevation 10–600 m. (0–2000 ft.) 600–700 m. (2000–2300 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 ophiochilus, known only from the northern part of the Palomar Mountains in southwestern Riverside County, is distinctive by having small, more or less terete, fascicled leaves; it is known to hybridize with C. crassifolius at one locality.

Ceanothus ophiochilus is in the Center for Plant Conservation’s National Collection of Endangered Plants.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 90. FNA vol. 12, p. 108.
Parent taxa Rhamnaceae > Ceanothus > subg. Ceanothus Rhamnaceae > Ceanothus > subg. Cerastes
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. 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. 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) S. Boyd: T. S. Ross & Arnseth, Phytologia 70: 29, figs. 1–4. (1991)
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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