Whitethorn Ceanothus

Ceanothus cordulatus

Native to:
Mexico, United States

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Taxonomy

Division:
Magnoliophyta | - Flowering plants
Family:
Rhamnaceae
Genus:
Ceanothus
Species:
Ceanothus cordulatus
USDA Symbol:
CECO

Growth Characteristics

Life Cycle:
Perennial
Growth Habit:
Shrub
Height:
150 cm
Light Requirements:
Full Sun
Drought Tolerance:
High
Bloom Months:
may,jun,jul
Bloom Colors:
white
Landscaping Shrub:
Yes

Wildlife Benefits

Bees:
★☆☆☆☆ Documented bee visitation (GBIF)
Butterflies & Moths:
★☆☆☆☆ Documented Lepidoptera association (GBIF)
Caterpillars:
★★☆☆☆ Recorded caterpillar host plant (HOSTS Database)

Keystone Species Ranking

Caterpillar Keystone:
★★★★☆ Butterfly & moth species supported by this genus (NWF)

Host Plant for Caterpillars

Ceanothus Silkmoth (Hyalophora euryalus), Columbia silk moth (Hyalophora columbia), Drepanulatrix carnearia, Drepanulatrix nevadaria, Drepanulatrix quadraria, Kaslo silkmoth (Hyalophora "kasloensis"), Saturnia albofasciata, Western tent caterpillar (Malacosoma californica), California tortoiseshell (Nymphalis californica), Pacuvius Duskywing (Erynnis pacuvius), Pale Swallowtail (Papilio eurymedon)

Reported Fauna Sightings

Bees: Black-tailed bumble bee (Bombus melanopygus), Fuzzy-horned bumble bee (Bombus mixtus), Yellow-faced bumble bee (Bombus vosnesenskii) Moths:Western tent caterpillar (Malacosoma californica)

Garden & Ecology Notes

Wildlife Value:
bees, butterflies, birds, deer browse
Fragrant:
Yes
Fire Ecology:
Requires fire for germination
Fire Notes:
Resprouts vigorously from root crown after fire. Seeds require heat or fire scarification for germination; fire stimulates mass seedling recruitment.

Soil Requirements

Soil Type:
rocky, well-drained, nutrient-poor soil
pH:
5.5 - 7.5 (slightly acidic to neutral)
Drainage:
excellent drainage required
Moisture:
dry to moderate
Notes:
prefers open, sunny locations in native range

Propagation & Germination

Stratification:
Warm then cold/moist stratification (double dormancy) — 90–120 days
Scarification:
Seed coat scarification required before sowing
Germination Time:
30–90 days
Notes:
Hot water treatment or scarification followed by cold stratification improves germination. Seeds have hard seed coats and double dormancy.

The above propagation data sourced from Claude AI

Pre-treatment: Seeds are placed in fine mesh bags, soaked for 10 seconds in boiling water and then immediately transferred in cold water. Seeds are then placed into a 1% hydrogen peroxide (3:1 water/3% hydrogen peroxide) soak for 24 hours, rinsed, and placed in water for an additional 4 hours. Seeds are sown into trays filled with stabilized medium plugs (Q-plugs). Trays are sealed inside plastic bags and placed into refrigeration at 1 to 3 °C for 90 days. Trays are checked weekly and kept moist throughout the stratification period. If mold is evident, trays should be treated with 1% hydrogen peroxide.

Establishment: Ceanothus cordulatus, also known as whitethorn ceanothus or white ceanothus, is generally found in Oregon, California, Nevada and within mattoral vegetation association of California. There is a variation in the pre-planting propagule treatments across the protocols, with one suggesting that seeds germinate at greenhouse temperatures without any specific treatment.

Source: npn.rngr.net