Flora of North America species comparison

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Ceanothus papillosus

Ceanothus confusus

wartleaf ceanothus

Rincon Ridge ceanothus
Habit Shrubs, evergreen, 1–5 m. Stems erect to ascending, not rooting at nodes; branchlets green to reddish brown, not thorn-tipped, round in cross section, ± flexible to rigid, densely tomentulose. Shrubs, 0.1–0.6 m, matlike to moundlike.
Stems

prostrate, spreading, or weakly ascending, often rooting at proximal nodes;

branchlets brown to reddish brown, ± rigid, glabrous or sparsely puberulent.
Leaves

petiole 1–3 mm;

blade cupped to flat, linear, narrowly oblong, or oblong-elliptic, 12–50 × 6–15 mm, base obtuse to rounded, margins minutely glandular-denticulate, revolute, glands 17–31, apex obtuse, truncate, or retuse, abaxial surface pale green, densely villosulous to tomentulose, adaxial surface dark green, sparsely puberulent and glandular-papillate; pinnately veined.

not fascicled, not crowded, shorter than internodes;

petiole 0–2 mm;

blade flat to ± cupped, elliptic to ± oblong or obovate, 10–20 × 5–14 mm, base obtuse to cuneate, margins thick or slightly revolute, slightly wavy, sharply dentate to spinose-dentate, teeth 3–9, apex acute or retuse, with an apical tooth, abaxial surface grayish green, strigillose on veins, adaxial surface green, dull, glabrous.
Inflorescences

axillary or terminal, racemelike, 2–8 cm.

axillary, 1.5–3 cm.
Flowers

sepals, petals, and nectary deep blue.

sepals, petals, and nectary blue, lavender, or purple.
Capsules

2–3 mm wide, lobed;

valves smooth, viscid when young, not or weakly crested.

4–6 mm wide, lobed;

valves smooth, crested, horns subapical, prominent, erect, intermediate ridges weakly developed.
2n

= 24.

= 24.

Ceanothus papillosus

Ceanothus confusus
Phenology Flowering Mar–May. Flowering Feb–May.
Habitat Rocky ridges, slopes, and flats, chaparral, mixed evergreen forests. Rocky soils apparently derived from serpentine or volcanic substrates, chaparral, oak and pine woodlands, conifer forests.
Elevation 20–1500 m. (100–4900 ft.) 70–1000 m. (200–3300 ft.)
Distribution
from FNA
CA; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
from FNA
CA
Discussion

Ceanothus papillosus occurs in the Coast Ranges from San Francisco Bay south to the Santa Ynez Mountains, Ventura County, with disjunct populations in the Santa Ana Mountains, California, and Cerro Bola, in northern Baja California. The name C. papillosus var. roweanus was originally applied to low-growing plants with ascending to spreading, arcuate branches (H. McMinn 1939). M. Van Rensselaer and McMinn (1942) later emended the circumscription to include plants with linear leaves and retuse to truncate leaf apices, but these are found throughout the range of the species. Leaves with obtuse to truncate or retuse leaf apices also can be found on the same plant. Putative hybrids with C. integerrimus and C. oliganthus have been documented (McMinn 1944). Hybrids with C. thyrsiflorus have been named C. ×regius (Jepson) McMinn. Some putatively advanced generation hybrids have narrowly elliptic, weakly papillate leaves with obtuse apices, and sometimes have been misinterpreted as belonging to C. papillosus.

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

Ceanothus confusus is weakly defined and perhaps best treated as a part of C. divergens (L. Abrams and R. S. Ferris 1923–1960, vol. 3). At least some populations in the Hood Mountains (Napa and Sonoma counties) include plants with the habit and leaf morphology of both species, while other, more uniform populations appear intermediate; it remains to be determined whether this pattern is a product of primary or secondary intergradation.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 92. FNA vol. 12, p. 104.
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. 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. 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. thyrsiflorus, C. tomentosus, C. velutinus, C. verrucosus
Synonyms C. papillosus subsp. roweanus, C. papillosus var. roweanus
Name authority Torrey & A. Gray: Fl. N. Amer. 1: 268. (1838) J. T. Howell: Leafl. W. Bot. 2: 160. (1939)
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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