Flora of North America species comparison

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Ceanothus integerrimus

Ceanothus pauciflorus

deer brush

desert buckbrush, desert buckthorn, Mojave ceanothus
Habit Shrubs, deciduous, 1.5–3 m. Stems ascending to erect, not rooting at nodes; branchlets pale green, not thorn-tipped, round in cross section, flexible, glabrous or strigillose. Shrubs, 0.2–2 m, sometimes moundlike.
Stems

erect or weakly ascending to spreading, not rooting at nodes;

branchlets light gray to ashy gray, rigid, puberulent to tomentulose, hairs curly or wavy, glabrescent.
Leaves

not fascicled;

petiole 3–12 mm;

blade flat, lanceolate, elliptic, oblong-elliptic, or ovate, (10–)20–80 × 10–45 mm, base rounded, margins entire or denticulate distally, teeth 3–5, apex acute to obtuse, abaxial surface pale green, glabrate or puberulent, especially on veins, sometimes glabrescent, adaxial surface green, dull, glabrous or sparsely puberulent; usually 3-veined from base, rarely pinnately veined.

not fascicled;

petiole (0–)1–3 mm;

blade flat to ± cupped, elliptic, oblong-elliptic, obovate, or suborbiculate, 5–15(–20) × 3–14(–15) mm, base cuneate to rounded, margins thick, not revolute, entire or remotely denticulate, teeth 1–5(–7), apex acute to ± truncate, abaxial surface pale green to grayish green, glabrate or puberulent, hairs curly or wavy, glabrescent, adaxial surface grayish green, puberulent, hairs curly or wavy, glabrescent.
Inflorescences

usually terminal, rarely axillary, racemelike or paniclelike, 5–25 cm.

axillary, rarely racemelike, 0.7–3 cm.
Flowers

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

sepals and petals white to cream, sometimes pale blue or lavender;

nectary yellowish green, brown, or blue.
Capsules

4–5 mm wide, lobed;

valves smooth, viscid, not or weakly crested.

3.5–6 mm wide, not, or sometimes weakly, lobed;

valves smooth, horns lateral, prominent to minute or absent, spreading, intermediate ridges absent.
2n

= 24.

Ceanothus integerrimus

Ceanothus pauciflorus
Phenology Flowering May–Jul. Flowering Feb–May.
Habitat Rocky slopes, open sites, chaparral, conifer and mixed evergreen forests. Rocky slopes, ridges, alluvial fans, sagebrush and montane shrublands, pinyon and/or juniper and montane conifer woodlands.
Elevation 25–2600 m. (100–8500 ft.) 900–2900.
Distribution
from FNA
AZ; CA; NM; OR; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; NM; NV; TX; UT; n Mexico; c Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

G. T. Benson (1930) recognized four varieties in Ceanothus integerrimus, based on flower color, leaf blade shape, venation, and indumentum. With the exception of regional clines in indumentum density, N. C. Coile (1988) was unable to detect consistent patterns of variation correlated with ecological or geographical distribution. The types of C. integerrimus (D. Douglas in 1831) and C. andersonii (C. C. Parry in 1888) are notable in that they bear oblong leaf blades with one principal vein from the base; the basal pair of secondary veins are shorter than those distal to it and relatively short compared to those in leaves elsewhere in the species. This venation is restricted to only a few specimens from near Ben Lomond, Santa Cruz Mountains, California, and has not been seen since the collection by Parry. W. L. Jepson (1909–1943, vol. 2) suggested that the venation pattern may be correlated with the oblong leaf shape that is shown by the type specimens.

Young shoots of Ceanothus integerrimus were used by Native Americans in basketry and for arrow foreshafts (D. E. Moerman 1998).

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

Ceanothus pauciflorus as circumscribed here includes plants having flat to cupped leaf blades with a sparse to dense but not intertwined indumentum composed of short curly or wavy hairs, at least when young; this indumentum also occurs on the petiole and ultimate branchlets. Such plants in the United States have been treated either as C. greggii or C. vestitus (M. Van Rensselaer and H. McMinn 1942). However, R. McVaugh (1998) and D. O. Burge and K. Zhukovsky (2013) provided evidence that they should be treated as C. pauciflorus. Specimens from the desert slopes of the Sierra Nevada and San Bernardino Mountains, California, and a few scattered localities in western Arizona, have leaves similar in shape and dentation to those of C. perplexans, suggesting local hybridization.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 85. FNA vol. 12, p. 107.
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. 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. 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. andersonii, C. integerrimus var. californicus, C. integerrimus var. macrothyrsus, C. integerrimus var. puberulus C. greggii, C. greggii var. franklinii, C. vestitus
Name authority Hooker & Arnott: Bot. Beechey Voy., 329. (1838) de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 2: 33. (1825)
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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