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pine mat

Sonoma ceanothus

Habit Shrubs, evergreen, 0.2–0.3(–0.5) m, matlike. Shrubs, 0.5–1 m, often moundlike.
Stems

spreading, sometimes rooting at nodes;

branchlets green, sometimes tinged red, not thorn-tipped, usually round, sometimes angled, in cross section, flexible, puberulent.

erect to ascending, not rooting at nodes;

branchlets gray to grayish brown, rigid, strigillose, glabrescent.

Leaves

petiole 3–11 mm;

blade flat, elliptic to widely ovate, 12–45 × 6–20 mm, base obtuse to rounded, margins serrulate to denticulate, not revolute, usually not wavy, sometimes wavy, teeth 27–42, apex ± obtuse to rounded, abaxial surface pale green, pilosulous, adaxial surface green, pilosulous; usually pinnately veined, rarely 3-veined from base.

not fascicled;

petiole 0–1 mm;

blade cupped, widely obovate to suborbiculate, 5–12 × 2–10 mm, base cuneate, margins not revolute, wavy, spinose-dentate, teeth 2–4, apex widely notched;

abaxial surface pale green or grayish green and glaucous, strigillose on veins, adaxial surface shiny green, glabrous.

Inflorescences

axillary, umbel-like to racemelike, 1.3–4 cm.

axillary or terminal, 0.8–1.5 cm.

Flowers

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

sepals, petals, and nectary blue to lavender.

Capsules

4–5 mm wide, weakly lobed near apex;

valves smooth, crested.

4–5 mm wide, usually not, sometimes weakly lobed;

valves smooth, horns subapical, minute to ± prominent, erect, intermediate ridges absent.

2n

= 24.

Ceanothus diversifolius

Ceanothus sonomensis

Phenology Flowering Apr–Jun. Flowering Mar–Apr.
Habitat Well-drained slopes and canyons, open to shaded sites, mixed evergreen and conifer forests. Sandy to rocky soils derived mostly from volcanic substrates, slopes, ridges, chaparral.
Elevation 700–2300 m. (2300–7500 ft.) 100–700 m. (300–2300 ft.)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
[BONAP county map]
Discussion

Ceanothus diversifolius occurs in the North Coast Ranges and the western slopes of the Cascade Range and the Sierra Nevada; it often forms mats to two meters wide. Marginal teeth on young leaves are notable in having more or less persistent, narrowly conic glands, not seen elsewhere in Ceanothus.

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

Ceanothus sonomensis is distinctive in having spinose-dentate, few-toothed leaves, and slender fruit horns two to three millimeters; it occurs at a few scattered localities in the mountains of Napa and Sonoma counties.

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

Source FNA vol. 12, p. 94. FNA vol. 12, p. 103.
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. 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. 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. 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. spinosus, C. thyrsiflorus, C. tomentosus, C. velutinus, C. verrucosus
Synonyms C. decumbens
Name authority Kellogg: Proc. Calif. Acad. Sci. 1: 58. (1855) J. T. Howell: Leafl. W. Bot. 2: 162. (1939)
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