Flora of North America species comparison

The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Ceanothus thyrsiflorus

Ceanothus megacarpus

blue blossom, blue blossom ceanothus

big pod 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, 1.5–6 m. Stems erect to ascending, not rooting at nodes; branchlets grayish brown to brown, flexible, appressed puberulent to tomentulose, hairs straight.
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.

sometimes alternate, not fascicled, sometimes crowded;

petiole 1–5 mm;

blade flat to cupped, oval, elliptic, or oblanceolate, 10–25(–33) × 5–19 mm, base cuneate to rounded, margins thick, usually entire, rarely remotely denticulate, teeth 5–7, apex obtuse, abaxial surface pale green, glabrous or sparsely strigillose on veins, adaxial surface green, glabrous.
Inflorescences

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

axillary, 1–2 cm.
Flowers

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

sepals and petals white;

nectary blue to black.
Capsules

3–4 mm wide, weakly lobed;

valves smooth, viscid, not crested.

7–12 mm wide, not lobed;

valves smooth or rugulose to weakly ridged near apex;

horns subapical, prominent, erect, often rugulose, or weakly developed to absent, intermediate ridges absent.
2n

= 24.

= 24.

Ceanothus thyrsiflorus

Ceanothus megacarpus
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 2 (2 in the flora).

Some populations of Ceanothus megacarpus are polymorphic for leaf arrangement. Plants assignable to either var. insularis or var. megacarpus based on leaf arrangement may have fruits intermediate to both varieties. Putative hybrids between var. megacarpus and C. cuneatus were reported by H. McMinn (1944), but their variable leaf arrangement (alternate and opposite on the same plant) may also represent intermediates between var. insularis and var. megacarpus.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Leaves mostly alternate; capsule valves rugulose to weakly ridged near apex; horns prominent.
var. megacarpus
1. Leaves mostly opposite; fruit valves smooth; horns weakly developed or absent.
var. insularis
Source FNA vol. 12, p. 90. FNA vol. 12, p. 97.
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. 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. 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. megacarpus var. insularis, C. megacarpus var. megacarpus
Synonyms C. thyrsiflorus var. chandleri, C. thyrsiflorus var. repens C. macrocarpus
Name authority Eschscholtz: Mém. Acad. Imp. Sci. St. Pétersbourg Hist. Acad. 10: 285. (1826) — (as thyrsiflora) Nuttall: N. Amer. Sylv. 2: 46. (1846)
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).



Type/paste one or more Latin names into the boxes above; matching taxa will show up below the box as you type. You can use the up/down arrow keys to move through the list.

(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Fabaceae, Apiaceae, Boraginaceae, and Polemoniaceae.)

Choose a data source: Flora of North America, OregonFlora

The species comparison tool is brought to you by:
Northwest Wildflowers