Flora of North America species comparison

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Ceanothus thyrsiflorus

Ceanothus foliosus

blue blossom, blue blossom ceanothus

wavy leaf 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, evergreen, 0.3–3.5 m. Stems erect, ascending, arcuate, or prostrate, not rooting at nodes; branchlets green, not thorn-tipped, round or slightly angled in cross section, flexible, villosulous.
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 1–3 mm;

blade flat or ± folded lengthwise, narrowly elliptic to oblong-elliptic or oblanceolate, 5–24 × 3–13 mm, base obtuse to rounded, margins entire or weakly glandular-denticulate most of length, ± thick, not revolute, usually wavy, sometimes not wavy, teeth 31–42, apex obtuse, abaxial surface pale green to grayish green, villosulous or glabrous and sometimes sparsely puberulent on veins, adaxial surface dark green, glabrous or sparsely puberulent; pinnately veined or faintly 3-veined from base.
Inflorescences

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

axillary, umbel-like to racemelike, 1–3.5(–7) cm.
Flowers

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

sepals, petals, and nectary pale to dark blue.
Capsules

3–4 mm wide, weakly lobed;

valves smooth, viscid, not crested.

3–4 mm wide, weakly lobed at apex;

valves smooth, not or weakly crested.
2n

= 24.

Ceanothus thyrsiflorus

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

Varieties 3 (3 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaf blade abaxial surfaces moderately to densely villosulous.
var. medius
1. Leaf blade abaxial surfaces glabrous or sometimes sparsely puberulent on veins.
→ 2
2. Leaf blades ± folded lengthwise, margins wavy, glandular-denticulate.
var. foliosus
2. Leaf blades flat to ± folded lengthwise, margins not to weakly wavy, entire or weakly denticulate near apex.
var. vineatus
Source FNA vol. 12, p. 90. FNA vol. 12, p. 93.
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. 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
Subordinate taxa
C. foliosus var. foliosus, C. foliosus var. medius, C. foliosus var. vineatus
Synonyms C. thyrsiflorus var. chandleri, C. thyrsiflorus var. repens
Name authority Eschscholtz: Mém. Acad. Imp. Sci. St. Pétersbourg Hist. Acad. 10: 285. (1826) — (as thyrsiflora) Parry: Proc. Davenport Acad. Nat. Sci. 5: 172. (1889)
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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