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Bolinas ceanothus, Mason's ceanothus

Otay Mountain ceanothus

Habit Shrubs, 0.6–2 m. Stems erect to ascending, not rooting at nodes; branchlets dark brown, rigid, ± tomentulose. Shrubs, 1–3.5 m. Stems erect to ascending, not rooting at nodes; branchlets grayish brown to brown, ± flexible to rigid, tomentulose.
Leaves

not fascicled;

petiole 1–2 mm;

blade flat, usually elliptic or oval, sometimes suborbiculate, 7–21 × 4–13 mm, base rounded to ± cuneate, margins not revolute, denticulate most of length, teeth 9–17, apex obtuse, rounded to truncate, abaxial surface pale green to grayish green, strigose on veins, glabrate, adaxial surface dark green, glabrous.

not fascicled;

petiole 0–2 mm;

blade flat to ± cupped, widely elliptic to obovate, 5–13 × 4–10 mm, base cuneate, margins revolute, sometimes wavy, coarsely denticulate near apex, teeth 3–5, apex truncate, retuse, or cuspidate, abaxial surface green, tomentulose, adaxial surface green, glabrous or sparsely puberulent.

Inflorescences

axillary, 1–2.5 cm.

axillary or terminal, 0.6–1.8 cm.

Flowers

sepals, petals, and nectary deep blue to purple.

sepals and petals white;

nectary tan to brown.

Capsules

3–4 mm wide, not lobed;

valves smooth, horns apical, minute, not rugose, intermediate ridges absent.

4–6 mm wide, weakly lobed;

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

2n

= 24.

Ceanothus masonii

Ceanothus otayensis

Phenology Flowering Feb–Apr. Flowering Jan–Apr.
Habitat Soils derived from serpentine, chaparral, pine forests. Rocky slopes, chaparral.
Elevation 100–500 m. (300–1600 ft.) 500–1100 m. (1600–3600 ft.)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; Mexico (Baja California)
[BONAP county map]
Discussion

Ceanothus masonii occurs only at a few localities on Bolinas Ridge, Marin County. With the exception of its leaf morphology, it bears a close resemblance to C. gloriosus var. exaltatus.

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

Ceanothus otayensis is known from the Otay and San Miguel Mountains, southern San Diego County, with at least one locality in northern Baja California. McMinn described C. otayensis as a hybrid between C. crassifolius and C. perplexans. However, neither of the putative parents occurs sympatrically with C. otayensis, and its populations do not display the increased variation expected from hybridization.

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

Source FNA vol. 12, p. 103. FNA vol. 12, p. 108.
Parent taxa Rhamnaceae > Ceanothus > subg. Cerastes 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. 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. 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
Name authority McMinn: Madroño 6: 171. (1942) McMinn: in M. van Rensselaer and H. McMinn, Ceanothus, 273, fig. 102. (1942) — as hybrid
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