Print Report

A0741 Ceanothus thyrsiflorus Scrub Alliance

Type Concept Sentence: This shrubland alliance of Oregon''s and California''s outer coast is characterized by the dominance of Ceanothus thyrsiflorus.

Common (Translated Scientific) Name: Blueblossom Scrub Alliance

Colloquial Name: Blueblossom Scrub

Hierarchy Level:  Alliance

Type Concept: This shrubland alliance is characterized by the dominance of Ceanothus thyrsiflorus. Other shrubs present may include Adenostoma fasciculatum, Arctostaphylos manzanita, Baccharis pilularis, Ceanothus incanus, Ceanothus integerrimus, Ceanothus velutinus, Gaultheria shallon, Heteromeles arbutifolia, Lupinus arboreus, Quercus dumosa, Toxicodendron diversilobum, and Vaccinium ovatum. Emergent conifers may be present. The herbaceous layer is sparse. This alliance is known from the outer Coast Ranges of Oregon and California. This vegetation grows on ridges and upper slopes between 10 and 600 m elevation. The climate is seasonal, with most precipitation falling as rain between November and April. Average yearly rainfall totals vary between 100 and 250 cm, depending on location.

Diagnostic Characteristics: Ceanothus thyrsiflorus is dominant or codominant in the shrub canopy with >35% relative cover.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This alliance is only represented by two associations and one placeholder. Currently this alliance has only been sampled from Point Reyes National Seashore in California and may occur north into Oregon. Further inventory is required to fully document the range of this alliance.

Similar NVC Types: No Data Available
note: No Data Available
Physiognomy and Structure: This hemi-sclerophyllous, broad-leaved evergreen shrubland forms an intermittent to continuous canopy less than 6 m in height. Emergent conifers (10-15 m tall) may be present. The herbaceous layer is sparse.

Floristics: This shrubland is characterized by the dominance of Ceanothus thyrsiflorus. Other shrubs present may include Adenostoma fasciculatum, Arctostaphylos manzanita, Baccharis pilularis, Ceanothus incanus, Ceanothus integerrimus, Ceanothus velutinus, Gaultheria shallon, Heteromeles arbutifolia, Lupinus arboreus, Quercus dumosa, Toxicodendron diversilobum, and Vaccinium ovatum. Emergent conifers may be present. The herbaceous layer is sparse.

Dynamics:  Stands of this alliance are rarely self-sustaining. Stands establish after fire and are transitional to other vegetation types.
Environmental Description:  This shrubland alliance of Oregon''s and California''s outer Coast Ranges grows on ridges and upper slopes between 10 and 600 m elevation. The climate is seasonal, with most precipitation falling as rain between November and April. Average yearly rainfall totals vary between 100 and 250 cm, depending on location.
Geographic Range: This alliance is known from the outer Coast Ranges of Oregon and California and is reported to occur in the Oregon Coastal Zone.

Nations: US

States/Provinces:  CA, OR


Confidence Level: Moderate

Confidence Level Comments: No Data Available
Grank: GNR

Greasons: No Data Available
Type Name Database Code Classification Code
Class 2 Shrub & Herb Vegetation Class C02 2
Subclass 2.B Temperate & Boreal Grassland & Shrubland Subclass S18 2.B
Formation 2.B.1 Mediterranean Scrub & Grassland Formation F038 2.B.1
Division 2.B.1.Na Californian Scrub & Grassland Division D327 2.B.1.Na
Macrogroup 2.B.1.Na.2 Coastal Sagebrush - Black Sage - Coyotebrush Coastal Scrub Macrogroup M044 2.B.1.Na.2
Group 2.B.1.Na.2.c Californian North Coastal & Mesic Scrub Group G662 2.B.1.Na.2.c
Alliance A0741 Blueblossom Scrub Alliance A0741 2.B.1.Na.2.c
Association CEGL003198 Blueblossom - Coyotebrush - Pacific Poison-oak Shrubland CEGL003198 2.B.1.Na.2.c
Association CEGL003199 Blueblossom - California Huckleberry - Thimbleberry Shrubland CEGL003199 2.B.1.Na.2.c
Concept Lineage: equivalent to A.741

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available
Synonomy: = Ceanothus thyrsiflorus (Blue blossom chaparral) Alliance (Sawyer et al. 2009) [37.204.00]
= Ceanothus thyrsiflorus Shrubland Alliance (CNPS 2017) [37.204.00]
= Blue Brush Chaparral (#37820) (Holland 1986b)
= Blue blossom series (Sawyer and Keeler-Wolf 1995)
Concept Author(s): R.F. Holland (1986b); J.O. Sawyer and T. Keeler-Wolf (1995)

Author of Description: M.E. Hall

Acknowledgements: No Data Available

Version Date: 09-26-14
  • Bickford, C., and P. Rich. 1984. Vegetation and flora of the Landels-Hill Big Creek Reserve, Monterey Co., California, second edition. Environmental Field Program Publication No. 15. University of California, Santa Cruz, CA.
  • CNPS [California Native Plant Society]. 2015-2017. A manual of California vegetation [online]. California Native Plant Society, Sacramento, CA. [http://vegetation.cnps.org/].
  • Engles, E., and C. Genetti. 1984. Vegetation and flora. Pages 43-178 in: E. Engles, editor. The natural features of the Gamboa Point properties, Monterey County, California. Volume 1: Geology, history, vegetation and flora. Environmental Field Program Publication No. 13. University of California, Santa Cruz.
  • Evens, J. M., and E. Kentner. 2006. Classification of vegetation associations from the Mount Tamalpais Watershed, Nicasio Reservoir, and Soulajule Reservior in Marin County, California. Report for the Marin Municipal Water District. California Native Plant Society, Sacramento.
  • Evens, J., A. Klein, J. Taylor, T. Keeler-Wolf, and D. Hickson, principal investigators. 2006. Vegetation classification, descriptions, and mapping of the Clear Creek Management Area, Joaquin Ridge, Monocline Ridge, and Environs in San Benito and western Fresno counties, California. Final report prepared by California Native Plant Society and California Department of Fish and Game, Sacramento, CA. 273 pp.
  • Faber-Langendoen, D., J. Drake, M. Hall, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, M. Russo, K. Schulz, L. Sneddon, K. Snow, and J. Teague. 2013-2019b. Screening alliances for induction into the U.S. National Vegetation Classification: Part 1 - Alliance concept review. NatureServe, Arlington, VA.
  • Holland, R. F. 1986b. Preliminary descriptions of the terrestrial natural communities of California. Unpublished report prepared for the California Department of Fish and Game, Nongame-Heritage Program and Natural Diversity Database, Sacramento. 156 pp.
  • Keeler-Wolf, T., M. Schindel, and S. San. 2004. Point Reyes National Seashore, Golden Gate National Recreation Area, San Francisco Water Department Watershed Lands, Mount Tamalpais, Tomales Bay, and Samuel P. Taylor State Parks. Appendix B. Point Reyes National Seashore, Golden Gate National Recreation Area, and surrounding wildlands plant community classification and mapping project. Final report. California State Department of Fish and Game, Sacramento, CA.
  • Sawyer, J. O., T. Keeler-Wolf, and J. Evens. 2009. A manual of California vegetation. Second edition. California Native Plant Society, Sacramento CA. 1300 pp.
  • Sawyer, J. O., and T. Keeler-Wolf. 1995. A manual of California vegetation. California Native Plant Society, Sacramento. 471 pp.
  • Schirokauer, D., T. Keeler-Wolf, J. Meinke, and P. van der Leeden. 2003. Plant community classification and mapping project. Point Reyes National Seashore, Golden Gate National Recreation Area, San Francisco Water Department Watershed Lands, Mount Tamalpais, Tomales Bay, and Samuel P. Taylor State Parks. Final report. California State Department of Fish and Game, Wildlife and Habitat Data Analysis Branch, Sacramento, National Park Service, Point Reyes Station, and Aerial Information Systems, Redlands, CA. 82 pp. [http://biology.usgs.gov/npsveg/pore_goga/index.html]