Flora of North America species comparison

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Ceanothus masonii

Ceanothus crassifolius

Bolinas ceanothus, Mason's ceanothus

hoary-leaf ceanothus
Habit Shrubs, 0.6–2 m. Stems erect to ascending, not rooting at nodes; branchlets dark brown, rigid, ± tomentulose. Shrubs, 1.5–4 m. Stems erect, not rooting at nodes; branchlets grayish brown to brown, ± flexible to rigid, tomentulose, hairs straight.
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 2–6 mm;

blade flat to ± cupped, elliptic to widely elliptic, 12–25(–30) × 8–15(–23) mm, base obtuse to rounded, margins thick or revolute, entire to denticulate most of length, teeth 8–19, apex obtuse to rounded, abaxial surface pale green to white, tomentulose to glabrate, adaxial surface green, sparsely tomentulose, hairs straight, glabrescent.
Inflorescences

axillary, 1–2.5 cm.

axillary or terminal, 1–2 cm.
Flowers

sepals, petals, and nectary deep blue to purple.

sepals and petals white;

nectary blue to black.
Capsules

3–4 mm wide, not lobed;

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

5–9 mm wide, sometimes weakly lobed at apex;

valves viscid, smooth, horns lateral, prominent, erect, intermediate ridges absent.
2n

= 24.

= 24.

Ceanothus masonii

Ceanothus crassifolius
Phenology Flowering Feb–Apr.
Habitat Soils derived from serpentine, chaparral, pine forests.
Elevation 100–500 m. (300–1600 ft.)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; nw Mexico
[WildflowerSearch map]
[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.)

Varieties 2 (2 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaf blade abaxial surfaces densely tomentulose, veins obscured, margins denticulate and revolute.
var. crassifolius
1. Leaf blade abaxial surfaces sparsely tomentulose to glabrate, veins evident, margins entire to weakly denticulate, thick to weakly revolute.
var. planus
Source FNA vol. 12, p. 103. FNA vol. 12, p. 98.
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. 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. thyrsiflorus, C. tomentosus, C. velutinus, C. verrucosus
Subordinate taxa
C. crassifolius var. crassifolius, C. crassifolius var. planus
Name authority McMinn: Madroño 6: 171. (1942) Torrey: in War Department [U.S.], Pacif. Railr. Rep. 4(5): 75. (1857)
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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