Flora of North America species comparison

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Ceanothus thyrsiflorus

Ceanothus microphyllus

blue blossom, blue blossom ceanothus

littleleaf buckbrush, sandflat ceanothus
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, 0.4–0.7 m. Stems erect to ascending, not rooting at nodes; branchlets reddish green or yellow-green, not thorn-tipped, round in cross section, flexible, usually puberulent, sometimes strigillose.
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.

often fascicled;

petiole 0.5–1 mm;

blade flat, elliptic, ovate-elliptic, or narrowly obovate, 2–10 × 1–6 mm, base cuneate, margins entire or weakly denticulate distally, not wavy, teeth 5–9, apex rounded or obtuse, abaxial surface pale green, puberulent on veins, adaxial surface green, glabrous; pinnately veined or 3-veined from base (venation obscure).
Inflorescences

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

axillary or terminal, umbel-like or ± racemelike, 1–3 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.

3–4.5 mm wide, lobed;

valves smooth, not crested.
2n

= 24.

Ceanothus thyrsiflorus

Ceanothus microphyllus
Phenology Flowering Mar–Jun. Flowering Mar–Jun.
Habitat Sandy or rocky flats and slopes, maritime chaparral, open sites in mixed evergreen and conifer forests. Sandy flats, shrublands, pine-oak woodlands.
Elevation 10–600 m. (0–2000 ft.) 0–200 m. (0–700 ft.)
Distribution
from FNA
CA; OR; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; FL; GA
[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.)

Short-statured plants of Ceanothus microphyllus with ovate-elliptic leaves, evident venation, and racemelike inflorescences have been called C. serpyllifolius (M. Van Rensselaer and H. McMinn 1942; W. H. Duncan and J. T. Kartesz 1981). Ceanothus serpyllifolius is treated here as part of C. microphyllus, because of continuous variation in leaf size, shape, and inflorescence architecture. Ceanothus serpyllifolius also has been applied to small-leaved, short-statured plants of C. americanus, some of which may be hybrids between that species and C. microphyllus (N. C. Coile 1988).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 90. FNA vol. 12, p. 83.
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. 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. 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. serpyllifolius
Name authority Eschscholtz: Mém. Acad. Imp. Sci. St. Pétersbourg Hist. Acad. 10: 285. (1826) — (as thyrsiflora) Michaux: Fl. Bor.-Amer. 1: 154. (1803)
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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