"Ceanothus" comes from (
keánōthos), which was applied by
Theophrastus (371–287 BC) to a spiny 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. 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. 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 The following species list is based on the treatments in the
Flora of North America Volume 12 (2016) and
A Taxonomic Conspectus of Ceanothus subgenus Cerastes (Rhamnaceae) by Burge et. al. (2016). Supplementary names are provided by
Plants of the World Online and
The Plant List.
Subgenus Ceanothus Ceanothus subgenus
Ceanothus consists of
evergreen or
deciduous species with thin scale-like
stipules, alternate leaves,
branchlets that may be thorn-tipped, and inflorescences that are generally
raceme-like to
panicle-like, or occasionally
umbel-like. The capsules lack horns, and are sometimes crested. Depending on the authority, there are about 21 to 32 species recognized in subgenus
Ceanothus. This subgenus is widely distributed across North America, from Canada, the United States and Mexico to Central America (Costa Rica, Guatemala, Panama). Many species in this subgenus have burls (root crowns) that can withstand
wildfires, allowing them to respond to fire by resprouting. •
Ceanothus americanus L. – New Jersey tea; red root •
Ceanothus arboreus Greene – feltleaf ceanothus •
Ceanothus buxifolius Willd. ex Schult. & Schult.f. •
Ceanothus caeruleus Lag •
Ceanothus cordulatus Kellogg – whitethorn ceanothus •
Ceanothus cyaneus Eastw. – San Diego buckbrush •
Ceanothus dentatus Torr. & A.Gray – sandscrub ceanothus •
Ceanothus depressus Benth. – junco •
Ceanothus diversifolius Kellogg – pinemat •
Ceanothus fendleri A.Gray – Fendler's ceanothus •
Ceanothus fernandezii •
Ceanothus foliosus Parry – wavyleaf ceanothus • subsp.
foliosus Parry • subsp.
medius (McMinn) C.L.Schmidt • subsp.
vineatus (McMinn) C.L.Schmidt •
Ceanothus griseus (Trel. ex B.L.Rob.) McMinn – Carmel ceanothus •
Ceanothus hearstiorum Hoover & J.B.Roof – Hearst Ranch buckbrush •
Ceanothus herbaceus Raf. – Jersey tea •
Ceanothus impressus Trel. – Santa Barbara ceanothus •
Ceanothus incanus Torr. & A.Gray – coast whitethorn •
Ceanothus integerrimus Hook. & Arn. – deerbrush ceanothus •
Ceanothus lemmonii Parry – Lemmon's ceanothus •
Ceanothus leucodermis Greene – chaparral whitethorn •
Ceanothus martini M.E.Jones – Martin's ceanothus •
Ceanothus microphyllus Michx. – littleleaf buckbrush •
Ceanothus ochraceus Suess. •
Ceanothus oliganthus Nutt. – hairy ceanothus • subsp.
oliganthus Nutt. • subsp.
sorediatus (Hook. & Arn.) C.L.Schmidt •
Ceanothus palmeri Trel. – Palmer ceanothus •
Ceanothus papillosus Torr. & A.Gray – wartleaf ceanothus •
Ceanothus parryi Trel. – Parry Ceanothus •
Ceanothus parvifolius (S.Watson) Trel. – littleleaf ceanothus •
Ceanothus pendletonensis D.O.Burge, Rebman, & M.R.Mulligan •
Ceanothus sanguineus Pursh – redstem ceanothus •
Ceanothus spinosus Nutt. – green bark ceanothus •
Ceanothus thyrsiflorus Eschsch. – blueblossom •
Ceanothus tomentosus Parry – woolyleaf ceanothus •
Ceanothus velutinus Dougl. ex Hook. – snowbrush ceanothus • subsp.
laevigatus (Torr. & A.Gray) Piper & Beattie • subsp.
velutinus Dougl. ex Hook.
Subgenus Cerastes Ceanothus subgenus
Cerastes (
S. Watson) Weberbauer consists of evergreen species with thick, wart-like stipules, branchlets that are not thorn-tipped, and leaves that are usually oppositely arranged (except in
C. verrucosus and
C. megacarpus var.
megacarpus). The leaves of plants in this subgenus are leathery in texture. The inflorescences are generally
umbel-like, and rarely
raceme-like. The capsules may be horned or not, and are usually not crested (except in
C. divergens and
C. gloriosus). Depending on the authority, there are about 25 to 29 species recognized in subgenus
Cerastes. This subgenus is found in the mountainous western parts of the United States and Mexico, with most species restricted to
California. Species in this subgenus strictly reproduce by seeds. •
Ceanothus arcuatus McMinn – arching ceanothus •
Ceanothus bolensis S.Boyd & J.E.Keeley – Cerro Bola ceanothus •
Ceanothus confusus J.T. Howell – Rincon Ridge ceanothus •
Ceanothus × connivens Greene – trailing buckbrush •
Ceanothus crassifolius Torr. – hoaryleaf ceanothus •
Ceanothus cuneatus (Hook.) Nutt. – buckbrush • subsp.
cuneatus (Hook.) Nutt. • subsp.
fascicularis (McMinn) C.L.Schmidt • subsp.
rigidus (Nutt.) C.L.Schmidt • subsp.
sonomensis (Howell) C.L.Schmidt •
Ceanothus decornutus V.T.Parker – Nicasio ceanothus •
Ceanothus divergens Parry – Calistoga ceanothus •
Ceanothus ferrisiae McMinn – coyote ceanothus •
Ceanothus fresnensis Dudley ex Abrams – Fresno ceanothus •
Ceanothus gloriosus J.T. Howell – Point Reyes ceanothus • subsp.
exaltatus (Howell) C.L.Schmidt • subsp.
gloriosus J.T. Howell • subsp.
masonii (McMinn) C.L.Schmidt • subsp.
porrectus (Howell) C.L.Schmidt •
Ceanothus jepsonii Greene – Jepson ceanothus • subsp.
albiflorus (Howell) C.L.Schmidt • subsp.
jepsonii Greene •
Ceanothus maritimus Hoover – maritime ceanothus •
Ceanothus masonii McMinn – Mason's ceanothus •
Ceanothus megacarpus Nutt. – bigpod ceanothus • subsp.
insularis (Eastw.) P.H.Raven • subsp.
megacarpus Nutt. •
Ceanothus ophiochilus Boyd, Ross & Arnseth – Vail Lake ceanothus •
Ceanothus otayensis H. E. McMinn – Otay Mountain buckbrush •
Ceanothus pauciflorus Moc. & Sessé ex DC. – Mojave ceanothus •
Ceanothus perplexans Trel. – cup-leaved ceanothus •
Ceanothus pinetorum Coville – Coville ceanothus •
Ceanothus prostratus Benth. – prostrate ceanothus • subsp.
confusus (Howell) C.L.Schmidt • subsp.
prostratus Benth. • subsp.
pumilus (Greene) C.L.Schmidt •
Ceanothus pumilus Greene – dwarf ceanothus •
Ceanothus purpureus Jepson – hollyleaf ceanothus • subsp.
divergens (Parry) C.L.Schmidt • subsp.
purpureus Jepson •
Ceanothus roderickii Knight – Pine Hill buckbrush •
Ceanothus sonomensis J.T. Howell – Sonoma ceanothus •
Ceanothus verrucosus Nutt. – wart-stem ceanothus
Hybrids Ceanothus have few natural barriers to genetic exchange, as they share a common diploid chromosome number and lack strong isolating mechanisms, resulting in a number of
hybrids and integradation between species. Hybridization usually only occurs within subgenera, as crosses across subgenera produce sterile
progeny. The role of hybridization creates difficulties in reliably circumscribing
Ceanothus species, and many species were formerly recognized as hybrids, like
Ceanothus otayensis and
Ceanothus arcuatus. Some authorities do not recognize even named hybrids due to the difficulty of keying them out. There are at least 44 interspecific combinations reported in the literature. The following hybrids have been described: •
Ceanothus × lobbianus •
Ceanothus × lorenzenii •
Ceanothus × mendocinensis •
Ceanothus × rugosus •
Ceanothus × serrulatus •
Ceanothus ×
vanrensselaeri Roof •
Ceanothus × veitchianus The status of the following hybrids is unresolved: •
Ceanothus ×
arnoldii Dippel •
Ceanothus × bakeri Greene ex McMinn •
Ceanothus ×
burkwoodii auct. •
Ceanothus ×
burtonensis Renss. •
Ceanothus ×
cyam L.W.Lenz •
Ceanothus ×
delilianus Spach •
Ceanothus ×
flexilis McMinn •
Ceanothus × humboldtensis •
Ceanothus ×
intermedius Koehne •
Ceanothus ×
pallidus Koehne •
Ceanothus ×
pallidus Lindl. •
Ceanothus ×
roseus Koehne ==Distribution==