Ceanothus velutinus

snowbrush

Rhamnaceae

The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivsion - Spermatophyta (seed plants). Division - Magnoliophyta (flowering plants). Class - Magnoliopsida (dicotyledons). Subclass - Rosidae. Order - Rhamnales. Family - Rhamnaceae (buckthorn). Genus - Ceanothus L. ( Ceanothus). Species - Ceanothus velutinus Douglas ex Hook. (snowbrush ceanothus).

Ecology: Though stands of snowbrush ceanothus may begin to deteriorate after 15 years, the natural life span of snowbrush ceanothus is greater than 25 years. Snowbrush ceanothus is an early to mid-seral species. It invades recently disturbed sites, particularly burned sites.Snowbrush ceanothus has been described as moderately shade tolerant to very intolerant: It grows on open, sunny sitesand in wooded areas. Though snowbrush ceanothus occurs as an understory species, it is soon shaded out with increasing development of tree cover. Snowbrush ceanothus is generally considered an important early to mid-seral species in most Douglas-fir forests of the northern Rockies and Pacific Northwest.

Identification

Snowbrush ceanothus is a [nitrogen fixing] native evergreen shrub. It generally grows 0.5-2.7 m tall , though it may also reach heights of 4 m. The leaves are alternate, 2.5-7.5 cm long, and 1.5-5 cm wide [there is a very pronounced W or M shaped by the veins in the leaf]. The inflorescence of snowbrush ceanothus is less than 12 cm long, and branched with many flowers.

Snowbrush ceanothus forms large, dense colonies. Thickets may be up to 10 m wide and are often dense and impenetrable.

Threats

Snowbrush ceanothus tolerates moderate browsing, and a level of use consistent with 40% removal of current annual twig growth has been suggested. Heavy browsing may damage snowbrush ceanothus, and wildlife exclusion results in healthy, robust plants.

Fire effects: Snowbrush ceanothus burns "quite hot". The foliage contains volatile oils that may contribute to fire hazard [this may be an adaptation to increase fire severity, thereby killing surrounding trees to open canopy and create favorable conditions for C. velutinus to reestablish]...Snowbrush ceanothus has dormant, ground-stored seed that requires heat treatment to germinate. Snowbrush ceanothus is promoted by fire, regenerating from seed stimulated by fire. Snowbrush ceanothus also sprouts vigorously from the root crown after fire. Resprouting may be an adaptation to recurring fires, allowing for rapid growth and recovery. Fire creates conditions more favorable for snowbrush ceanothus growth by removing the overstory.

Reproduction

Seed production - Snowbrush ceanothus produces abundant seed crops. It 1st produces seed at about 3 to 6 years of age, and continues producing until past age 20. Sprouts can produce prolific seed crops 8 years after top-kill.

Seed dispersal - When Snowbrush ceanothus seeds ripen, they are forcibly ejected from the pods. The heavy snowbrush ceanothus seeds generally stay where they fall, gradually filtering into the duff and soil unless they are carried off by small animals.

Seed banking - Snowbrush ceanothus seed is stored in the soil for up to 200 years, and can regenerate from seed stored in the soil for up to "several centuries"...Snowbrush ceanothus contributed 25% of the seeds found in soil samples taken from central Idaho Douglas-fir and grand fir habitat types. Snowbrush ceanothus seeds are less successfully stored in wet soils.

Germination - Snowbrush ceanothus has a very hard, impermeable seedcoat that must be cracked, abraded, or exposed to heat in order for germination to occur. Though exposure to heat is most effective in promoting germination, other disturbance (e.g. timber harvest) may stimulate snowbrush ceanothus germination by abrading the seedcoat.

Seedling establishment/growth - Although large numbers of seeds typically germinate after fire, snowbrush ceanothus may experience high early mortality. In general, snowbrush ceanothus is a slow-growing species.

Asexual regeneration - Snowbrush ceanothus sprouts from the root crown following damage to stems and/or top removal. Sprout growth of 51-65 cm after 1 year, and growth of 1.0-2.1 m after 5 years has been observed. The ability to sprout may be a function of age and vigor of the plant when it is damaged.

Species Distribution

Citation

USDA Plants Database
USDA, NRCS. 2016. The PLANTS Database (http://plants.usda.gov, 4 February 2016). National Plant Data Team, Greensboro, NC 27401-4901 USA.

Flora of North America
Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.

Intermountain Herbarium
Consortium of Intermountain Herbaria. 2016. http//:intermountainbiota.org/portal/index.php. Accessed on February 04.

Burke Museum Plant Image Collection
The plant image collection at the Burke Museum, University of Washington.

Jepson Manual
The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA., hardcover; 1600 pages. ISBN-13: 978-0520253124.