Flora of North America species comparison

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Ceanothus thyrsiflorus

Ceanothus americanus

blue blossom, blue blossom ceanothus

céanothe d'amérique, Jersey tea ceanothus, New Jersey redroot, New Jersey-tea
Habit Shrubs, sometimes arborescent, evergreen, 0.5–6 m. Stems erect, usually ascending to arcuate, rarely prostrate, not rooting at nodes; branchlets green, not thorn-tipped, angled in cross section, flexible, not tuberculate, sparsely puberulent or glabrous. Shrubs, deciduous, 0.8–1.5 m. Stems erect to ascending, not rooting at nodes; branchlets usually green, sometimes reddish brown, not thorn-tipped, round or slightly angled in cross section, flexible, puberulent, glabrescent.
Leaves

petiole 3–10 mm;

blade flat to cupped, elliptic to ovate, 10–40(–50) × 5–15(–20) mm, base obtuse to rounded, margins denticulate to serrulate, usually not revolute, sometimes incompletely revolute, teeth glandular, 23–48, apex obtuse, abaxial surface pale green, sparsely puberulent to villosulous or glabrate, veins prominently raised, puberulent to villosulous, adaxial surface dark green, glabrate; 3-veined from base.

petiole 4–13 mm;

blade not aromatic, flat, ovate to ovate-oblong, (20–)30–100 × 15–64 mm, herbaceous, not resinous, base rounded, margins serrate to serrulate, teeth 54–130+, apex usually acuminate to acute, rarely obtuse, abaxial surface pale green, puberulent, especially on veins, adaxial surface dark green, dull, puberulent, especially on major veins; 3-veined from base.
Inflorescences

terminal, usually racemelike, rarely paniclelike, 2.5–9 cm.

terminal or axillary, paniclelike, cylindric to conic, 3–14 cm.
Flowers

sepals, petals, and nectary usually pale to deep blue, rarely white.

sepals, petals, and nectary white.
Capsules

3–4 mm wide, weakly lobed;

valves smooth, viscid, not crested.

4–6 mm wide, not lobed;

valves ± rugulose, crested.
2n

= 24.

= 24.

Ceanothus thyrsiflorus

Ceanothus americanus
Phenology Flowering Mar–Jun. Flowering May–Aug.
Habitat Sandy or rocky flats and slopes, maritime chaparral, open sites in mixed evergreen and conifer forests. Open areas in forests and woodlands, abandoned fields, sandhills, prairies.
Elevation 10–600 m. (0–2000 ft.) 80–300 m. (300–1000 ft.)
Distribution
from FNA
CA; OR; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WI; WV; ON; QC
[WildflowerSearch map]
[BONAP county map]
Discussion

Ceanothus thyrsiflorus occurs along the coast from Coos County, Oregon, south to Santa Barbara County, California, and disjunctly near Eréndira, Baja California. A wide range of growth forms characterize this species and the closely related C. griseus, including plants ranging from almost prostrate to arborescent, sometimes with single trunks. Prostrate plants from several maritime bluffs along the California coast have been called C. thyrsiflorus var. repens McMinn; they retain their stature under cultivation. Named hybrids include C. ×regius (Jepson) McMinn (C. thyrsiflorus × C. papillosus) and C. ×vanrensselaeri Roof (C. thyrsiflorus × C. incanus). H. McMinn (1944) reported hybrids with C. foliosus.

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

Ceanothus americanus is closely related to C. herbaceus and C. sanguineus. Ceanothus herbaceus differs in having narrower leaf blades, short peduncles, and globose to hemispheric inflorescences. Ceanothus sanguineus, which occurs in western North America (except for a disjunct population in the Upper Peninsula of Michigan), differs by smooth fruit valves and inflorescences borne on stems older than the current year. Three varieties, var. americanus, var. intermedius, and var. pitcheri, have been recognized within C. americanus, based on leaf shape and indumentum (M. L. Fernald 1950; H. A. Gleason and A. Cronquist 1991), but N. C. Coile (1988) provided evidence for clinal intergradation among them.

An infusion of Ceanothus americanus leaves or bark was used widely by Native Americans as an anti-inflammatory and to treat gastrointestinal ailments (D. E. Moerman 1998). The dried leaves were used as a tea substitute during the American Revolution (N. L. Britton and A. Brown 1896–1898, vol. 2).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 90. FNA vol. 12, p. 82.
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. 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. tomentosus, C. velutinus, C. verrucosus
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. 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. thyrsiflorus var. chandleri, C. thyrsiflorus var. repens C. americanus var. intermedius, C. americanus var. pitcheri, C. intermedius
Name authority Eschscholtz: Mém. Acad. Imp. Sci. St. Pétersbourg Hist. Acad. 10: 285. (1826) — (as thyrsiflora) Linnaeus: Sp. Pl. 1: 195. (1753)
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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