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Mountain Whitethorn
Ceanothus cordulatus
About Mountain Whitethorn (Ceanothus cordulatus) Nurseries Show All Photos Ceanothus cordulatus is a species of shrub in the buckthorn family (Rhamnaceae) known by the common names Mountain Whitethorn and Whitethorn Ceanothus. It is native to California and adjacent sections of Oregon, Nevada, and Baja California, where it grows on mountain ridges and other forested areas. In California its major population is in the Sierras. This is a spreading shrub growing usually wider than tall and up to about 1.5 meters. The stems are gray, with the twigs yellow-green in color and fuzzy in texture when new. The evergreen leaves are alternately arranged and up to 3 centimeters long. Each is oval in shape with three ribs and generally not toothed. The leaves may be hairy or not. The flower cluster is panicle-shaped, up to about 4 centimeters long. The flowers are white to off-white with five sepals and five petals. The fruit is a rough, ridged capsule up to half a centimeter long. It has three valves inside, each containing a seed. This is a plant for high elevation gardens, from 4,000 ft. to 10,000 ft. At lower elevations it grows slowly and performs poorly. It is one of the most cold-tolerant of the Ceanothus.
Plant Description
Plant Type

Max. Height
3 - 6 ft (0.9 - 1.8 m)

Max. Width
9 ft (2.7 m)

Upright, Spreading

Fragrant - Pleasant

Growth Rate
Fast, Slow

Winter Deciduous, Winter Semi-Deciduous, Evergreen

Flower Color
White, Cream

Flowering Season
Spring, Summer, Winter

Native Status

Natural Setting
Site Type
Rocky ridges, open areas in higher elevation mountains.

Sun, Part Shade

Elevation ?
300' - 13935'

Annual Precip. ?
10.2" - 166.8"

Summer Precip. ?
0.27" - 4.44"

Coldest Month ?
8.4° F - 52.0° F

Hottest Month ?
32.1° F - 79.5° F

Humidity ?
0.26 vpd - 26.90 vpd

Soil Description
Prefers sandy or loamy soils. Does not grow well in clay soils.

Soil PH
5.0 - 7.0

Fast, Medium, Slow

Cold Tolerance(° F)
Tolerates cold to -20° F

Sunset Zones ?
1, 2, 3, 6, 7, 14, 15, 16, 18

Companion Plants
Use with other mountain species such as Firs (Abies sp. and Pseudotsuga sp.), Manzanita (Arctostaphylos mewukka or nevadensis or patula), Dogwood (Cornus sp.), Western Juniper (Juniperus occidentalis), Tanoak (Notholithocarpus densiflorus), Ninebark (Physocarpus capitatus), Pines (Pinus sp.), Quaking Aspen (Populus tremuloides), Canyon Live Oak (Quercus chrysolepis), and Giant Redwood (Sequoiadendron giganteum)

Wildlife Attracted
Numerous birds and insects are attracted to the flowers. Plants in the Ceanothus genus are host plants to the Spring Azure, Echo Blue, Pacuvius Duskywing, California Tortoiseshell, Pale Swallowtail, and Hedgerow Hairstreak butterflies.

Landscaping Information
Water Requirement ?
Very Low
Extremely Low
Very Low
Moderate - High

Seldom Used

Propagation ?
For propagating by seed: Hot water and 3 mos. stratification. Alternative treatment: boil in water 1 min.; then, instead of stratification, soak in 400 ppm GA, 13 hrs.; air dry 4 days; soak in 3% thiourea 5 mins. Seeds may then be sown or dried again and stored. In this quick treatment gave 25% germination for Ceanothus cordulatus. (Adams et al. 1961).

Common uses
Bank Stabilization, Hedges, Bird Gardens, Butterfly Gardens, Bee Gardens

Nursery Availability
Sometimes Available

Other Names
Common Names
Snow Bush, Whitethorn Ceanothus

Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

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