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Santa Barbara ceanothus

chaparral whitethorn

Habit Shrubs, evergreen, 0.5–3 m. Stems erect, not rooting at nodes; branchlets brown, not thorn-tipped, round in cross section, flexible, puberulent. Shrubs, evergreen, 1.5–4 m. Stems erect, not rooting at nodes; branchlets light green or grayish green and glaucous, thorn-tipped, round in cross section, rigid, glabrous.
Leaves

petiole 0–4 mm;

blade ± flat to strongly cupped, oblong, elliptic, or suborbiculate, 5–20(–25) × 2.5–17(–20) mm, base rounded, margins serrulate, thick to weakly or strongly revolute, teeth 11–29, apex obtuse to rounded, abaxial surface pale green, villosulous, adaxial surface dark to medium green, sparsely puberulent, not glandular papillate; pinnately veined, veins furrowed.

petiole 3–7 mm;

blade flat, ovate to oblong-elliptic, 5–30 × 3–15 mm, base rounded to subcordate, margins usually entire to minutely glandular-serrulate, rarely serrate, glands 16–20, apex acute to obtuse, abaxial surface grayish green, glaucous, glabrous, adaxial surface green, ± glaucous, dull, usually glabrous, sometimes appressed villosulous; 3-veined from base.

Inflorescences

axillary or terminal, umbel-like to racemelike, 1.2–3.5 cm.

axillary, usually paniclelike, sometimes racemelike, (3–)5–15 cm.

Flowers

sepals, petals, and nectary blue.

sepals, petals, and nectary white to blue.

Capsules

3–4 mm wide, lobed;

valves smooth, crested.

3–5 mm wide, lobed;

valves smooth, viscid, not crested.

2n

= 24.

Ceanothus impressus

Ceanothus leucodermis

Phenology Flowering Apr–Jun.
Habitat Rocky slopes, chaparral, oak woodlands, conifer forests.
Elevation 200–1800 m. (700–5900 ft.)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Ceanothus leucodermis is a common, often dominant species of chaparral in the mountains of central and southern California. This species is notable in producing serrate to serrulate leaves on stump sprouts following fire (M. Van Rensselaer and H. McMinn 1942). Putative hybrids and advanced generation intermediates with C. oliganthus occur throughout the southern Coast and Transverse ranges of California (McMinn 1944).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Leaf blades oblong to elliptic, 5–11(–14) × 2.5–8(–12) mm, strongly cupped, margins strongly revolute.
var. impressus
1. Leaf blades widely elliptic to suborbiculate, 11–20(–25) × 7–17(–20) mm, ± flat to cupped, margins thick to weakly revolute.
var. nipomensis
Source FNA vol. 12, p. 91. FNA vol. 12, p. 86.
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. 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
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. 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
Subordinate taxa
C. impressus var. impressus, C. impressus var. nipomensis
Name authority Trelease: Proc. Calif. Acad. Sci., ser. 2, 1: 112. (1888) Greene: Bull. Misc. Inform. Kew 1895: 15. (1895)
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