{{Short description|Species of flowering plant}} {{Speciesbox |image = Chorizanthe valida.jpg |status = G1 |status_system = TNC |genus = Chorizanthe |species = valida |authority = S.Wats. }}
'''''Chorizanthe valida''''' is a rare species of flowering plant in the buckwheat family known by the common name '''Sonoma spineflower'''. It is endemic to West Marin, Marin County, California, where it is known from only one remaining natural population at Point Reyes National Seashore. It was thought to be extinct until 1980 when the Point Reyes population was discovered.<ref>{{Cite web |url=http://northcoastcnps.org/cgi-bin/inv/inventory.cgi/Go?_id=chorizanthe_valida&sort=DEFAULT&search=Chorizanthe%20valida |title=California Native Plant Society Rare Plants Profile |access-date=2011-07-26 |archive-url=https://web.archive.org/web/20120423191917/http://northcoastcnps.org/cgi-bin/inv/inventory.cgi/Go?_id=chorizanthe_valida&sort=DEFAULT&search=Chorizanthe%20valida |archive-date=2012-04-23 |url-status=dead }}</ref>
''Chorizanthe valida'' is a federally listed endangered species.
This plant is erect in form, reaching up to about 30 centimeters tall. The inflorescence is a cluster of flowers with each flower surrounded by six reddish or gray bracts, each tipped with a straight awn. The awns are bright red when new and age ivory white.<ref name=reveal>Reveal, J. L. [http://www.plantsystematics.org/reveal/pbio/eriog/choriz/valida.html ''C. valida''.] Taxonomic Treatment of Eriogonoideae (Polygonaceae).</ref> They are not hard or hooked in shape like those of many other ''Chorizanthe''.<ref name=five>USFWS. [http://ecos.fws.gov/docs/five_year_review/doc3558.pdf ''Chorizanthe valida'' Five-year Review.] August 2010.</ref> The flower is a few millimeters long and white or pink in color. [[File:Chorizanthe valida counting.jpg|thumb|left|200px|Staff and California Native Plant Society volunteers perform a survey for Sonoma spineflower.]] This rare plant once had a wider distribution; specimens were collected many decades ago in neighboring Sonoma County.<ref name=five/> Today it is limited to Point Reyes where there is one natural population at Abbotts Lagoon and one that has been reintroduced by humans near Bull Point.<ref name=five/> The number of individuals is variable.<ref name=five/>
The local habitat is coastal prairie on deep, sandy soils.<ref name=five/> The soil, remnants of a Pleistocene dune system, can bear only drought-tolerant plants because it cannot retain much water.<ref name=five/>
Research suggests that areas with grazing cattle contain a larger number of plants than areas where animals are excluded, but the plants in the exclusion areas are larger and have more flowers.<ref name=five/><ref name=tnc>[http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Chorizanthe+valida The Nature Conservancy]</ref> Cattle do not eat the rare plant and may in fact help clear the land of invasive non-native plants, such as velvetgrass (''Holcus lanatus'').<ref name=five/> The land around Abbotts Lagoon is a cattle pasture today.<ref name=five/>
This species occurs within the bounds of a protected National Seashore, so its habitat will not be developed, and it is protected from such activities as mining, dredging, and horseback riding activity.<ref name=five/> Threats that do remain include damage by hikers and off-road vehicles.<ref name=five/> The overall effects of cattle on the land are not certain; they may actually be a positive force in the life of the rare plant.<ref name=five/> The plant is limited to two relatively small populations, so any one severe event such as wildfire or drought could drive it to extinction.<ref name=five/><ref name=nps>Coppoletta, M. and B. Moritsch. [http://www.nature.nps.gov/yearinreview/yir2000/pages/05_restoration/05_01_coppoletta.html Restoring the abundance of the endangered Sonoma spineflower.] {{webarchive|url=https://web.archive.org/web/20111021085730/http://nature.nps.gov/YearinReview/yir2000/pages/05_restoration/05_01_coppoletta.html |date=2011-10-21 }} Natural Resource Year in Review 2000. National Park Service.</ref>
==References== {{Reflist}}
==External links== *[http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?5936,5941,5980 Jepson Manual Treatment: ''Chorizanthe valida''] *[https://plants.usda.gov/java/profile?symbol=CHVA USDA Plants Profile: ''Chorizanthe valida''] *[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250060101 Flora of North America: ''Chorizanthe valida''] *[http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&where-taxon=Chorizanthe+valida ''Chorizanthe valida'' Photo gallery]
==Further reading== *<small>Rilla, E. and L. Bush. (2009). [http://ucanr.org/sites/uccemarin/files/31000.pdf The changing role of agriculture in Point Reyes National Seashore.] University of California Cooperative Extension Marin.</small>
==External links== *[http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=2059 Calflora Database: ''Chorizanthe valida'' (Sonoma spineflower)] *[http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=19362 Jepson eFlora (TJM2) treatment of ''Chorizanthe valida''] *[http://calphotos.berkeley.edu/cgi-bin/img_query?rel-taxon=begins+with&where-taxon=Chorizanthe+valida UC Photos gallery: ''Chorizanthe valida'']
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valida Category:Endemic flora of California Category:Natural history of the California chaparral and woodlands Category:Natural history of Marin County, California Category:Point Reyes National Seashore Category:West Marin Category:Plants described in 1877 Category:Taxa named by Sereno Watson Category:Critically endangered flora of California Category:Endemic flora of the San Francisco Bay Area