View source for Biology:Ceanothus

{{Short description|Genus of flowering plants}}
{{Automatic taxobox
|name=''Ceanothus''
|image=Ceanothus americanus.jpg
|image_caption=''[[Biology:Ceanothus americanus|Ceanothus americanus]]'' flowers
|taxon=Ceanothus
|authority=[[Biography:Carl Linnaeus|L.]]<ref name="GRIN">{{cite web |url=http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?2210 |title=Genus: ''Ceanothus'' L. |work=Germplasm Resources Information Network |publisher=United States Department of Agriculture |date=2004-02-10 |access-date=2012-04-25 |archive-url=https://web.archive.org/web/20090114223302/http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?2210 |archive-date=2009-01-14 |url-status=dead }}</ref>
|subdivision_ranks=Species
|subdivision=See text
|synonyms = ''Forrestia'' <small>Raf.</small>
|synonyms_ref = <ref name = powo/>
}}

'''''Ceanothus''''' is a [[Biology:Genus|genus]] of about 50–60 species of [[Biology:Actinorhizal plant|nitrogen-fixing]] [[Biology:Shrub|shrub]]s and small [[Earth:Tree|tree]]s in the buckthorn family ([[Biology:Rhamnaceae|Rhamnaceae]]).<ref name=EB1911>{{cite EB1911|wstitle=Ceanothus}}</ref><ref>{{Cite web |url=http://web.uconn.edu/mcbstaff/benson/Frankia/Rhamnaceae.htm |title=Untitled Document |access-date=2015-03-25 |archive-date=2016-03-04 |archive-url=https://web.archive.org/web/20160304062125/http://web.uconn.edu/mcbstaff/benson/Frankia/Rhamnaceae.htm |url-status=dead }}</ref><ref name=powo/><ref name=cf/> Common names for members of this genus are '''buckbrush''', '''California lilac''', '''soap bush''', or just '''ceanothus'''.<ref name=usda/><ref name=waterwise/><ref name=FPSMM/> ''"Ceanothus"'' comes from {{lang-grc|κεάνωθος}} (''keanōthos''), which was applied by [[Biography:Theophrastus|Theophrastus]] (371–287 BC) to an Old World plant believed to be ''[[Biology:Cirsium arvense|Cirsium arvense]]''.<ref>{{cite book |author=Elmore, Francis H. |title=Trees and Shrubs of the Southwest Uplands |publisher=Western National Parks Association |year=1976 |pages=195 |isbn=0-911408-41-X}}</ref><ref name="Austin">{{cite book |url=https://books.google.com/books?id=eS7lX_rC3GEC |first=Daniel F. |last=Austin |title=Florida Ethnobotany |publisher=CRC Press |year=2004 |isbn=978-0-8493-2332-4 |page=291}}</ref>

The genus is native to [[Earth:North America|North America]] with the highest diversity on the western coast.<ref name=powo/><ref name=bonapdiv/><!--can't infer from this that diversity is highest in CA and not MX; need a better source--> Some species (e.g., ''[[Biology:Ceanothus americanus|C. americanus]]'') are restricted to the eastern United States and southeast Canada, and others (e.g., ''[[Biology:Ceanothus caeruleus|C. caeruleus]]'') extend as far south as Guatemala. Most are shrubs {{convert|0.5|-|3|m|ft}} tall, but ''[[Biology:Ceanothus arboreus|C. arboreus]]'' and ''[[Biology:Ceanothus thyrsiflorus|C. thyrsiflorus]]'', both native to California, can be small multi-trunked trees up to {{convert|6|-|7|m|ft}} tall.

==Taxonomy and etymology==
There are two subgenera within this genus: ''Ceanothus'' and ''Cerastes''. The former clade is less drought-resistant, having bigger leaves. The evolution of these two clades likely started with a divergence in the niches filled in local communities, rather than a divergence on the basis of geography.<ref name="AckerlySchwilk2006"/>

The Californian species of ''Ceanothus'' are commonly known collectively as California lilacs, with individual species having more descriptive common names. Species native elsewhere have other common names such as New Jersey tea for ''C. americanus'', as its leaves were used as a black tea substitute during the American Revolution.<ref name=EB1911/><ref name=feis>
{{cite web
 |url=http://www.fs.fed.us/database/feis/plants/shrub/ceaame/all.html
 |title=''Ceanothus americanus''
 |author=Coladonato, Milo
 |year=1993
 |work=Fire Effects Information System (online)
 |publisher=U.S.D.A; Forest Service
 |location=Rocky Mountain Research Station, Fire Sciences Laboratory (Producer)
 |access-date=March 3, 2016
}}</ref> In garden use, most are simply called by their scientific names or an adaptation of the scientific name, such as 'Maritime ceanothus' for ''C. maritimus''.

===Species===
[[File:Ceanothus cuneatus1.jpg|right|thumb|Flowers of ''Ceanothus cuneatus'' (buck brush) in Pinnacles National Park]]
{{As of|December 2023}}, accepted species are:<ref name=powo/><ref name="PlantList">{{cite web | url = http://www.theplantlist.org/1.1/browse/A/Rhamnaceae/Ceanothus/ | title = The Plant List entry for ''Myrica'' | date = September 2013 | website = [[Biology:The Plant List|The Plant List]], v.1.1 | publisher = [[Organization:Royal Botanic Gardens, Kew|Royal Botanic Gardens, Kew]] and the [[Organization:Missouri Botanical Garden|Missouri Botanical Garden]] | access-date = 15 December 2020}}</ref>

{{div col|colwidth=350px}}
* ''[[Biology:Ceanothus americanus|Ceanothus americanus]]'' <small>L.</small> &ndash; New Jersey tea; red root<ref>[http://wisplants.uwsp.edu/scripts/detail.asp?spcode=CEAAME University of Wisconsin–Stevens Point Plant Database: ''Ceanothus americanus''] {{webarchive|url=https://web.archive.org/web/20070116012715/http://wisplants.uwsp.edu/scripts/detail.asp?SpCode=CEAAME |date=2007-01-16 }}</ref>
* ''[[Biology:Ceanothus arboreus|Ceanothus arboreus]]'' <small>Greene</small> – feltleaf ceanothus
* ''Ceanothus arcuatus'' <small>McMinn</small>
* ''Ceanothus × bakeri'' {{small|Greene ex McMinn}}
* ''Ceanothus bolensis'' <small>S.Boyd & J.E.Keeley</small>
* ''[[Biology:Ceanothus buxifolius|Ceanothus buxifolius]]'' <small>Willd. ex Schult. & Schult.f.</small>
* ''[[Biology:Ceanothus caeruleus|Ceanothus caeruleus]]'' <small>Lag</small>
* ''[[Biology:Ceanothus confusus|Ceanothus confusus]]'' <small>J.T. Howell</small> – Rincon Ridge ceanothus
* ''Ceanothus × connivens'' <small>Greene</small> – trailing buckbrush
* ''[[Biology:Ceanothus cordulatus|Ceanothus cordulatus]]'' <small>Kellogg</small> – whitethorn ceanothus
* ''[[Biology:Ceanothus crassifolius|Ceanothus crassifolius]]'' <small>Torr.</small> – hoaryleaf ceanothus
* ''[[Biology:Ceanothus cuneatus|Ceanothus cuneatus]]'' <small>(Hook.) Nutt.</small> – buckbrush
** subsp. ''cuneatus'' <small>(Hook.) Nutt.</small>
** subsp. ''fascicularis'' <small>(McMinn) C.L.Schmidt</small>
** subsp. ''rigidus'' <small>(Nutt.) C.L.Schmidt</small>
** subsp. ''sonomensis'' <small>(Howell) C.L.Schmidt</small>
* ''[[Biology:Ceanothus cyaneus|Ceanothus cyaneus]]'' <small>Eastw.</small> – San Diego buckbrush
* ''Ceanothus decornutus'' <small>V.T.Parker</small>
* ''[[Biology:Ceanothus dentatus|Ceanothus dentatus]]'' <small>Torr. & A.Gray</small> – sandscrub ceanothus
* ''[[Biology:Ceanothus depressus|Ceanothus depressus]]'' <small>Benth.</small> – junco
* ''[[Biology:Ceanothus divergens|Ceanothus divergens]]'' <small>Parry</small> – Calistoga ceanothus 
* ''[[Biology:Ceanothus diversifolius|Ceanothus diversifolius]]'' <small>Kellogg</small> – pinemat
* ''[[Biology:Ceanothus fendleri|Ceanothus fendleri]]'' <small>A.Gray</small> – Fendler's ceanothus
* ''Ceanothus fernandezii'' {{small|Villarreal, A.E.Estrada & Encina}}
* ''[[Biology:Ceanothus ferrisiae|Ceanothus ferrisiae]]'' <small>McMinn</small> – coyote ceanothus
* ''[[Biology:Ceanothus foliosus|Ceanothus foliosus]]'' <small>Parry</small> – wavyleaf ceanothus
** subsp. ''foliosus'' <small>Parry</small>
** subsp. ''medius'' <small>(McMinn) C.L.Schmidt</small>
** subsp. ''vineatus'' <small>(McMinn) C.L.Schmidt</small>
* ''[[Biology:Ceanothus fresnensis|Ceanothus fresnensis]]'' <small>Dudley ex Abrams</small> – Fresno ceanothus
* ''[[Biology:Ceanothus gloriosus|Ceanothus gloriosus]]'' <small>J.T. Howell</small> – Point Reyes ceanothus
** subsp. ''exaltatus'' <small>(Howell) C.L.Schmidt</small>
** subsp. ''gloriosus'' <small>J.T. Howell</small>
** subsp. ''masonii'' <small>(McMinn) C.L.Schmidt</small>
** subsp. ''porrectus'' <small>(Howell) C.L.Schmidt</small>
* ''[[Biology:Ceanothus griseus|Ceanothus griseus]]'' <small>(Trel. ex B.L.Rob.) McMinn</small> – Carmel ceanothus
* ''[[Biology:Ceanothus hearstiorum|Ceanothus hearstiorum]]'' <small>Hoover & J.B.Roof</small> – Hearst Ranch buckbrush
* ''[[Biology:Ceanothus herbaceus|Ceanothus herbaceus]]'' <small>Raf.</small> – Jersey tea
* ''Ceanothus × humboldtensis'' {{small|Roof}}
* ''[[Biology:Ceanothus impressus|Ceanothus impressus]]'' <small>Trel.</small> – Santa Barbara ceanothus
* ''[[Biology:Ceanothus incanus|Ceanothus incanus]]'' <small>Torr. & A.Gray</small> – coast whitethorn
* ''[[Biology:Ceanothus integerrimus|Ceanothus integerrimus]]'' <small>Hook. & Arn.</small> – deerbrush ceanothus
* ''[[Biology:Ceanothus jepsonii|Ceanothus jepsonii]]'' <small>Greene</small> – Jepson ceanothus
** subsp. ''albiflorus'' <small>(Howell) C.L.Schmidt</small>
** subsp. ''jepsonii'' <small>Greene</small>
* ''[[Biology:Ceanothus lemmonii|Ceanothus lemmonii]]'' <small>Parry</small> – Lemmon's ceanothus
* ''[[Biology:Ceanothus leucodermis|Ceanothus leucodermis]]'' <small>Greene</small> – chaparral whitethorn
* ''Ceanothus × lobbianus'' {{small|Hook.}}
* ''Ceanothus × lorenzenii'' {{small|(Jeps.) McMinn}}
* ''[[Biology:Ceanothus maritimus|Ceanothus maritimus]]'' <small>Hoover</small> – maritime ceanothus
* ''Ceanothus martini'' <small>M.E.Jones</small> – Martin's ceanothus
* ''[[Biology:Ceanothus masonii|Ceanothus masonii]]'' <small>McMinn</small> – Mason's ceanothus
* ''[[Biology:Ceanothus megacarpus|Ceanothus megacarpus]]'' <small>Nutt.</small> – bigpod ceanothus
** subsp. ''insularis'' <small>(Eastw.) P.H.Raven</small>
** subsp. ''megacarpus'' <small>Nutt.</small>
* ''Ceanothus × mendocinensis'' {{small|McMinn}}
* ''Ceanothus microphyllus'' <small>Michx.</small> – littleleaf buckbrush
* ''Ceanothus ochraceus'' <small>Suess.</small>
* ''[[Biology:Ceanothus oliganthus|Ceanothus oliganthus]]'' <small>Nutt.</small> – hairy ceanothus
** subsp. ''oliganthus'' <small>Nutt.</small>
** subsp. ''sorediatus'' <small>(Hook. & Arn.) C.L.Schmidt</small>
* ''[[Biology:Ceanothus ophiochilus|Ceanothus ophiochilus]]'' <small>Boyd, Ross & Arnseth</small> – Vail Lake ceanothus
* ''[[Biology:Ceanothus otayensis|Ceanothus otayensis]]'' <small>H. E. McMinn</small> – Otay Mountain buckbrush
* ''Ceanothus palmeri'' <small>Trel.</small> – Palmer ceanothus
* ''[[Biology:Ceanothus papillosus|Ceanothus papillosus]]'' <small>Torr. & A.Gray</small> – wartleaf ceanothus
* ''[[Biology:Ceanothus parryi|Ceanothus parryi]]'' <small>Trel.</small> – Parry Ceanothus
* ''[[Biology:Ceanothus parvifolius|Ceanothus parvifolius]]'' <small>(S.Watson) Trel.</small> – littleleaf ceanothus
* ''[[Biology:Ceanothus pauciflorus|Ceanothus pauciflorus]]'' <small>DC.</small>
* ''Ceanothus pendletonensis'' <small>D.O.Burge, Rebman, & M.R.Mulligan</small>
* ''Ceanothus perplexans'' <small>Trel.</small>
* ''[[Biology:Ceanothus pinetorum|Ceanothus pinetorum]]'' <small>Coville</small> – Coville ceanothus
* ''[[Biology:Ceanothus prostratus|Ceanothus prostratus]]'' <small>Benth.</small> – prostrate ceanothus
** subsp. ''confusus'' <small>(Howell) C.L.Schmidt</small>
** subsp. ''prostratus'' <small>Benth.</small>
** subsp. ''pumilus'' <small>(Greene) C.L.Schmidt</small>
* ''[[Biology:Ceanothus pumilus|Ceanothus pumilus]]'' <small>Greene</small> – dwarf ceanothus
* ''[[Biology:Ceanothus purpureus|Ceanothus purpureus]]'' <small>Jepson</small> – hollyleaf ceanothus
** subsp. ''divergens'' <small>(Parry) C.L.Schmidt</small>
** subsp. ''purpureus'' <small>Jepson</small>
* ''Ceanothus × regius'' {{small|(Jeps.) McMinn}}
* ''[[Biology:Ceanothus roderickii|Ceanothus roderickii]]'' <small>Knight</small> – Pine Hill buckbrush
* ''Ceanothus × rugosus'' {{small|Greene}}
* ''[[Biology:Ceanothus sanguineus|Ceanothus sanguineus]]'' <small>Pursh</small> – redstem ceanothus
* ''Ceanothus serpyllifolius'' <small>Nutt.</small> – Coastal Plain buckbrush
* ''Ceanothus × serrulatus'' {{small|McMinn}}
* ''[[Biology:Ceanothus sonomensis|Ceanothus sonomensis]]'' <small>J.T. Howell</small> – Sonoma ceanothus
* ''[[Biology:Ceanothus spinosus|Ceanothus spinosus]]'' <small>Nutt.</small> – green bark ceanothus
* ''[[Biology:Ceanothus thyrsiflorus|Ceanothus thyrsiflorus]]'' <small>Eschsch.</small> – blueblossom
* ''[[Biology:Ceanothus tomentosus|Ceanothus tomentosus]]'' <small>Parry</small> – woolyleaf ceanothus
* ''Ceanothus × veitchianus'' {{small|Hook.}}
* ''[[Biology:Ceanothus velutinus|Ceanothus velutinus]]'' <small>Dougl. ex Hook.</small> – snowbrush ceanothus
** subsp. ''laevigatus'' <small>(Torr. & A.Gray) Piper & Beattie</small>
** subsp. ''velutinus'' <small>Dougl. ex Hook.</small>
* ''[[Biology:Ceanothus verrucosus|Ceanothus verrucosus]]'' <small>Nutt.</small> – Barranca brush
{{div col end}}

===Species names with uncertain taxonomic status===
The status of the following species is unresolved:<ref name="PlantList"/>
{{div col|colwidth=350px}}
* ''Ceanothus atropurpureus'' <small>Raf.</small>
* ''Ceanothus chloroxylon'' <small>Nees</small>
* ''Ceanothus collinus'' <small>Douglas ex Knowles & Westc.</small>
* ''Ceanothus cuneatus'' <small>A.Gray</small>
* ''Ceanothus cuneatus'' <small>K.Brandegee</small>
* ''Ceanothus divergens'' <small>Poepp. ex Endl.</small>
* ''Ceanothus elongatus'' <small>Salisb.</small>
* ''Ceanothus glaber'' <small>Spach</small>
* ''Ceanothus laevigatus'' <small>Howell</small>
* ''Ceanothus lancifolius'' <small>Moench</small>
* ''Ceanothus leschenaultii'' <small>DC.</small>
* ''Ceanothus mocinianus'' <small>DC.</small>
* ''Ceanothus mystacinus'' <small>DC.</small>
* ''Ceanothus neumannii'' <small>Tausch</small>
* ''Ceanothus oblanceolatus'' <small>Davidson</small>
* ''Ceanothus pauciflorus'' <small>Moc. & Sessé ex DC.</small>
* ''Ceanothus pubiflorus'' <small>DC.</small>
* ''Ceanothus pulchellus'' <small>Delile ex Spach</small>
* ''Ceanothus scandens'' <small>D.Dietr.</small>
* ''Ceanothus spathulatus'' <small>Labill.</small>
* ''Ceanothus spinosus'' <small>Torr. & A. Gray</small>
* ''Ceanothus triqueter'' <small>Wall.</small>
{{div col end}}

===Hybrids===
The following hybrids have been described:<ref name="PlantList"/>
{{div col|colwidth=350px}}
* ''Ceanothus'' × ''arcuatus'' <small>McMinn</small>
* ''Ceanothus'' × ''bakeri'' <small>Greene ex McMinn</small>
* ''Ceanothus'' × ''flexilis'' <small>McMinn</small>
* ''Ceanothus'' × ''lobbianus'' <small>Hook.</small>
* ''Ceanothus'' × ''lorenzenii'' <small>(Jeps.) McMinn</small>
* ''Ceanothus'' × ''mendocinensis'' <small>McMinn</small>
* ''Ceanothus'' × ''otayensis'' <small>McMinn</small>
* ''Ceanothus'' × ''rugosus'' <small>Greene</small>
* ''Ceanothus'' × ''serrulatus'' <small>McMinn</small>
* ''Ceanothus'' × ''vanrensselaeri'' <small>Roof</small>
* ''Ceanothus'' × ''veitchianus'' <small>Hook.</small>
{{div col end}}

===Hybrid names with uncertain taxonomic status===
The status of the following hybrids is unresolved:<ref name="PlantList"/>
{{div col|colwidth=350px}}
* ''Ceanothus'' × ''arnoldii'' <small>Dippel</small>
* ''Ceanothus'' × ''burkwoodii'' <small>auct.</small>
* ''Ceanothus'' × ''burtonensis'' <small>Renss.</small>
* ''Ceanothus'' × ''cyam'' <small>L.W.Lenz</small>
* ''Ceanothus'' × ''delilianus'' <small>Spach</small>
* ''Ceanothus'' × ''humboldtensis'' <small>Roof</small>
* ''Ceanothus'' × ''intermedius'' <small>Koehne</small>
* ''Ceanothus'' × ''pallidus'' <small>Koehne</small>
* ''Ceanothus'' × ''pallidus'' <small>Lindl.</small>
* ''Ceanothus'' × ''roseus'' <small>Koehne</small>
{{div col end}}

==Description==
[[Image:Ceanothus arboreus 2.jpg|thumb|''Ceanothus arboreus'', illustrating the three basal leaf veins characteristic of this genus]]

===Growth pattern===
The majority of the species are [[Biology:Evergreen|evergreen]], but the handful of species adapted to cold winters are [[Biology:Deciduous|deciduous]]. The leaves are opposite or alternate (depending on species), small (typically 1–5&nbsp;cm long), simple, and mostly with serrated margins.

===Leaves and stems===
Ceanothus leaves may be arranged opposite to each other on the stem, or alternate. Alternate leaves may have either one or three main veins rising from the base of the leaf.<ref name="NSSN">Native Shrubs of the Sierra Nevada, John Hunter Thomas, Dennis R. Parnell, University of California Press, 1974, p. 70–77, [https://books.google.com/books?id=RgUUOn9Fx2wC&dq=ceanothus+one+vein&pg=PA74]</ref>

The leaves have a shiny upper surface that feels "gummy" when pinched between the thumb and forefinger, and the roots of most species have red inner root bark.<ref name=Tilford>Edible and Medicinal Plants of the West, Gregory L. Tilford, {{ISBN|0-87842-359-1}}</ref>

===Flowers and fruit===
[[Image:Ceanothus fendleri flower1.jpg|thumb|''Ceanothus fendleri'' blossom]]
The flowers are white, greenish&ndash;white, blue, dark purple-blue, pale purple or pink, maturing into a dry, three-lobed seed capsule.

The flowers are tiny and fragrant and produced in large, dense clusters. A few species are reported to be so intensely fragrant they are almost nauseating, and are said to resemble the odor of "boiling honey in an enclosed area".{{citation needed|date=October 2021}} The seeds of this plant can lie dormant for hundreds of years,{{citation needed|date=June 2014}} and ''Ceanothus'' species are typically dependent on forest fires to trigger germination of their seeds.<ref name=Tilford/>

Fruits are hard, nutlike capsules.<ref name=FPSMM>Flowering Plants of the Santa Monica Mountains, Nancy Dale, 2nd Ed., 2000, pp. 166–167</ref>

==Distribution==
[[Image:Ceanothus.jpg|thumb|right|''Ceanothus americanus'' (fruit left, flowers right)]]
Plants in this genus are widely distributed and can be found on dry, sunny hillsides from coastal scrub lands to open forest clearings, from near sea level to {{convert|9000|ft|m}} in elevation. These plants are profusely distributed throughout the Rocky Mountains from British Columbia south through Colorado, the Cascades of Oregon and California, and the Coastal Ranges of California.

''[[Biology:Ceanothus velutinus|Ceanothus velutinus]]'' is perhaps the most widespread member of this genus, occurring through much of western North America.<ref name=Tilford/> The plants in this genus often co-occur with one another, especially when they are more distantly related.<ref name="AckerlySchwilk2006">{{cite journal|last1=Ackerly|first1=D. D.|last2=Schwilk|first2=D. W.|last3=Webb|first3=C. O.|title=Niche evolution and adaptive radiation: Testing the order of trait divergence|journal=Ecology|volume=87|issue=sp7|year=2006|pages=S50–S61|issn=0012-9658|doi=10.1890/0012-9658(2006)87[50:NEAART]2.0.CO;2|pmid=16922302}}</ref>

==Uses==
[[File:Ceanothus integerrimus 01.jpg|thumb|''Ceanothus integerrimus'' (deerbrush) in Yosemite National Park]]

===Wildlife===
Ceanothus is a good source of nutrition for deer, specifically mule deer along the West Coast of the United States. However, the leaves are not as nutritious from late spring to early fall as they are in early spring. Porcupines and quail have also been seen eating stems and seeds of these shrubs. The leaves are a good source of protein and the stems and leaves have been found to contain a high amount of calcium.

===Cultivation===
Many ''Ceanothus'' species are popular ornamental plants for gardens. Dozens of [[Biology:Hybrid|hybrids]] and [[Biology:Cultivar|cultivar]]s have been selected, such as flexible ceanothus, ''Ceanothus × flexilis'' (''C. cuneatus'' × ''C. prostratus'').{{citation needed|date=January 2018}}

=== Royal Horticultural Society's Award of Garden Merit cultivars===
The following cultivars and [[Biology:Hybrid#Hybrid plants|hybrids]] have gained the Royal Horticultural Society's Award of Garden Merit ({{as of|2017|lc=y}}):<ref>{{cite web |url=https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf |title=AGM Plants - Ornamental |date=July 2017 |page=16 |publisher=Royal Horticultural Society |access-date=24 January 2018}}</ref> 
{{div col|colwidth=15em}}
*’Autumnal Blue’<ref>{{cite web 
|url=https://www.rhs.org.uk/Plants/91791/i-Ceanothus-i-Autumnal-Blue/Details
|title=RHS Plantfinder - ''Ceanothus'' 'Autumnal Blue'
|publisher=Royal Horticultural Society |access-date=21 January 2018}}</ref> 
*'Blue Mound'<ref>{{cite web|title=RHS Plant Selector - ''Ceanothus'' 'Blue Mound'|url=https://www.rhs.org.uk/Plants/63246/Ceanothus-Blue-Mound/Details | access-date=15 April 2020}}</ref> 
*'Burkwoodii'<ref>{{cite web|title=RHS Plant Selector - ''Ceanothus'' 'Burkwoodii'|url=https://www.rhs.org.uk/Plants/96855/Ceanothus-Burkwoodii/Details | access-date=15 April 2020}}</ref> 
*'Cascade'<ref>{{cite web|title=RHS Plant Selector - ''Ceanothus'' 'Cascade'|url=https://www.rhs.org.uk/Plants/91792/Ceanothus-Cascade/Details | access-date=15 April 2020}}</ref> 
*'Concha'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/97563/Ceanothus-Concha/Details
| title = ''Ceanothus'' 'Concha' | publisher = RHS | access-date = 12 April 2020}}</ref> 
*'Dark Star'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/95793/Ceanothus-Dark-Star/Details
| title = ''Ceanothus'' 'Dark Star' | publisher = RHS | access-date = 12 April 2020}}</ref> 
*'Gloire de Versailles'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/69338/Ceanothus-x-delileanus-Gloire-de-Versailles/Details
| title = Ceanothus × ''delileanus'' 'Gloire de Versailles' | publisher = RHS | access-date = 12 April 2020}}</ref> 
*'Mystery Blue'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/274981/Ceanothus-thyrsiflorus-Mystery-Blue/Details
| title = ''Ceanothus thyrsifolius'' 'Mystery Blue' | publisher = RHS | access-date = 12 April 2020}}</ref> 
*'Perle Rose'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/52985/Ceanothus-x-pallidus-Perle-Rose/Details
| title = ''Ceanothus'' × ''pallidus'' 'Perle Rose' | publisher = RHS | access-date = 12 April 2020}}</ref> 
*'Puget Blue'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/95971/Ceanothus-Puget-Blue/Details
| title = ''Ceanothus'' 'Puget Blue' | publisher = RHS | access-date = 12 April 2020}}</ref> 
*'Skylark'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/236885/Ceanothus-Skylark/Details
| title = ''Ceanothus'' 'Skylark' | publisher = RHS | access-date = 12 April 2020}}</ref> 
*'Topaze'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/46202/Ceanothus-x-delileanus-Topaze/Details
| title = ''Ceanothus'' × ''delineanus'' 'Topaze' | publisher = RHS | access-date = 12 April 2020}}</ref> 
*'Trewithen Blue'<ref>{{cite web | url = https://www.rhs.org.uk/Plants/3253/Ceanothus-arboreus-Trewithen-Blue/Details
| title = ''Ceanothus arboreus'' 'Trewithen Blue' | publisher = RHS | access-date = 12 April 2020}}</ref> 
*''C. thyrsifolius'' var. ''repens'' <ref>{{cite web | url = https://www.rhs.org.uk/Plants/94754/Ceanothus-thyrsiflorus-var-repens/Details
| title = ''Ceanothus thyrsifolius'' var. ''repens'' | publisher = RHS | access-date = 12 April 2020}}</ref> 
{{div col end}}

Other cultivars available include:-
{|
|- valign=top
|
*'Anchor Bay' <ref>[http://www.smgrowers.com/products/plants/plantdisplay.asp?strSearchText=Ceanothus&plant_id=1755&page=San Marcos Growers Horticulture Database: ''Ceanothus'' 'Anchor Bay']</ref>
*'Diamond Heights' (variegated leaves)<ref>[http://www.smgrowers.com/products/plants/plantdisplay.asp?plant_id=2992 San Marcos Growers Horticulture Database: ''Ceanothus griseus horizontalis'' 'Diamond Heights']</ref> 
|
*'Ray Hartman'<ref>[http://www.smgrowers.com/products/plants/plantdisplay.asp?strSearchText=Ceanothus&plant_id=372&page=San Marcos Growers Horticulture Database: ''Ceanothus'' 'Ray Hartman']</ref>
*'Snow Flurry'<ref>[http://www.smgrowers.com/products/plants/plantdisplay.asp?strSearchText=Ceanothus&plant_id=373&page= San Marcos Growers Horticulture Database: ''Ceanothus thyrsiflorus'' 'Snow Flurry']</ref>
|}

There are also more cultivars and hybrids of ''[[Biology:Ceanothus arboreus|Ceanothus arboreus]]'', ''[[Biology:Ceanothus griseus|Ceanothus griseus horizontalis]]'' (groundcovers), and ''[[Biology:Ceanothus thyrsiflorus|Ceanothus thyrsiflorus]]'' in the nursery trade.

====Propagation====
[[Earth:Plant propagation|Propagation]] of ceanothus is by [[Biology:Seed|seed]], following scarification and stratification. Seeds are soaked in water for 12 hours followed by chilling at 1&nbsp;°C for one to three months. It can also sprout from roots and/or stems. Seeds are stored in plant litter in large quantities. It is estimated that there are about two million seeds per acre in forest habitats. Seeds are dispersed propulsively from capsules and, it has been estimated, can remain viable for hundreds of years. In habitat, the seeds of plants in this genus germinate only in response to range fires and forest fires. {{Citation needed|date=December 2013}}

===Other uses===
Native Americans used the dried leaves of this plant as an herbal tea, and early pioneers used the plant as a substitute for black tea. Miwok Indians of California make baskets from Ceanothus branches. ''Ceanothus integerrimus'' has been used by North American tribes to ease childbirth.<ref>Moerman, D. (1988). ''Native American Ethnobotany''. Timber Press, Oregon.</ref>

== Nitrogen fixation ==
''Ceanothus'' is [[Biology:Actinorhizal plant|actinorhizal]], meaning it fixes nitrogen through a symbiotic relationship with ''[[Biology:Frankia|Frankia]].'' Six genera within Rhamnaceae are actinorhizal, but ''Ceanothus'' is the only genus not in the monophyletic tribe Colletieae. This suggests that actinorhizal symbiosis may have [[Biology:Convergent evolution|evolved twice]] in Rhamnaceae.<ref>{{Cite web|last=Vining|first=Susan|date=2020-02-26|title=Rhamnaceae {{!}} Frankia|url=https://frankia.mcb.uconn.edu/home/rhamnaceae/|access-date=2021-06-12|language=en-US}}</ref> ''[[Biology:Frankia|Frankia]]'' forms [[Biology:Root nodule|nodules]] on the roots of ''Ceanothus'', converting atmospheric nitrogen ({{chem|N|2}}) into [[Chemistry:Ammonia|ammonia]] ({{chem|NH|3}}) using [[Biology:Nitrogenase|nitrogenase]].<ref>{{Cite web|last=Vining|first=Susan|date=2020-02-26|title=Nodules {{!}} Frankia|url=https://frankia.mcb.uconn.edu/home/nolules/|access-date=2021-06-12|language=en-US}}</ref><ref>{{Cite web|last=Vining|first=Susan|date=2020-02-26|title=Nitrogen Fixation {{!}} Frankia|url=https://frankia.mcb.uconn.edu/frankia-biology/nitrogen-fixation/|access-date=2021-06-12|language=en-US}}</ref>

==References==
{{Reflist|refs=
<ref name=bonapdiv>{{cite web |title=Largest Genera in Continental North America |url=http://bonap.org/2015_SpecialtyMaps/Most%20Number%20of%20Native%20Species/Native%20Species%20per%20Genus.html |website=BONAP |access-date=29 September 2019}}</ref>
<ref name=cf>[http://www.calflora.org/cgi-bin/specieslist.cgi?where-genus=Ceanothus Calflora Database: Index of ''Ceanothus'' species native to California]</ref>
<ref name=powo>{{cite web |title=''Ceanothus'' L. |url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30006383-2 |website=Plants of the World Online |publisher=Royal Botanical Gardens Kew |access-date=2 December 2023}}</ref>
<ref name=usda>{{PLANTS |id=CEANO |taxon=Ceanothus |access-date=29 September 2019}}</ref>
<ref name=waterwise>McMahan, L. R. [https://extension.oregonstate.edu/sites/default/files/documents/1/waterwise-plant-profiles.pdf WaterWise Plant Profiles]. Oregon State University Extension Service.</ref>
}}

{{Taxonbar|from=Q311139}}

[[Category:Ceanothus| ]]
[[Category:Rhamnaceae genera]]

{{Sourceattribution|Ceanothus}}