Flora of North America species comparison

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Ceanothus papillosus

Ceanothus leucodermis

wartleaf ceanothus

chaparral whitethorn
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, 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 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.

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, racemelike, 2–8 cm.

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

sepals, petals, and nectary deep blue.

sepals, petals, and nectary white to blue.
Capsules

2–3 mm wide, lobed;

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

3–5 mm wide, lobed;

valves smooth, viscid, not crested.
2n

= 24.

= 24.

Ceanothus papillosus

Ceanothus leucodermis
Phenology Flowering Mar–May. Flowering Apr–Jun.
Habitat Rocky ridges, slopes, and flats, chaparral, mixed evergreen forests. Rocky slopes, chaparral, oak woodlands, conifer forests.
Elevation 20–1500 m. (100–4900 ft.) 200–1800 m. (700–5900 ft.)
Distribution
from FNA
CA; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
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 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.)
Source FNA vol. 12, p. 92. 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. 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. 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
Synonyms C. papillosus subsp. roweanus, C. papillosus var. roweanus
Name authority Torrey & A. Gray: Fl. N. Amer. 1: 268. (1838) Greene: Bull. Misc. Inform. Kew 1895: 15. (1895)
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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