Ceanothus is a genus of about 50–60 species of nitrogen-fixing shrubs and small trees in the buckthorn family (Rhamnaceae). Common names for members of this genus are buckbrush, California lilac, soap bush, or just ceanothus. "Ceanothus" comes from Ancient Greek: κεάνωθος (keanōthos), which was applied by Theophrastus to an Old World plant believed to be Cirsium arvense.
Ceanothus cuneatus is a species of flowering shrub known by the common names buckbrush and wedgeleaf ceanothus.
Ceanothus megacarpus is a species of flowering shrub known by the common name bigpod ceanothus. This Ceanothus is endemic to California, where its distribution extends along the Central Coast and includes the Channel Islands.
Ceanothus griseus is a species of flowering shrub known by the common names Carmel ceanothus and Carmel creeper. 'Carmel' refers to the Carmel-by-the-Sea region in California.
Ceanothus impressus is a species of shrub in the family Rhamnaceae known by the common name Santa Barbara ceanothus. It is endemic to the Central Coast of California, where it is known from San Luis Obispo and Santa Barbara Counties. It occurs in chaparral habitat.
Ceanothus ophiochilus is a rare species of flowering shrub known by the common name Vail Lake ceanothus, native to Southern California. It was not described until 1991.
Ceanothus confusus is a species of shrub in the family Rhamnaceae known by the common name Rincon Ridge ceanothus. It is endemic to northern California where it grows in the coastal mountains north of the San Francisco Bay Area. Its habitats include coniferous forest, woodland, and chaparral. This is a low, spreading shrub often forming a short mat up to about 1.2 meters wide. The stem is gray-brown with new twigs having a reddish color and fuzzy texture. The evergreen leaves are oppositely arranged. Each is up to 2 centimeters long and oval in shape with 3 to 5 large teeth. The upper surface is shiny green and the underside is paler and feltlike in texture with hairs along the veins. The inflorescence is a small cluster of blue or purple flowers. The fruit is a horned capsule about half a centimeter wide.
Ceanothus cordulatus is a species of shrub in the family Rhamnaceae known by the common names mountain whitethorn and whitethorn ceanothus. It is native to California and adjacent sections of Oregon, Nevada, and Baja California, where it grows on mountain ridges and other forested areas. This is a spreading shrub growing usually wider than tall and up to about 1.5 meters. The stems are gray, with the twigs yellow-green in color and fuzzy in texture when new. The evergreen leaves are alternately arranged and up to 3 centimeters long. Each is oval in shape with three ribs and generally not toothed. The leaves may be hairy or not. The inflorescence is panicle-shaped, up to about 4 centimeters long. The flowers are white to off-white with five sepals and five petals. The fruit is a rough, ridged capsule up to half a centimeter long. It has three valves inside, each containing a seed. It is a nitrogen-fixing plant, that is uniquely abundant in old-growth forest conditions when compared to similar types of nitrogen-fixing plants. In addition, Ceanothus cordulatus is known to be an important source of nitrogen patches for significantly longer times than other similar post-disturbance successional shrubs, following disturbance events such as forest fires.
Ceanothus ferrisiae is a rare species of shrub in the family Rhamnaceae. Its common name is coyote ceanothus.
Ceanothus gloriosus is a species of shrub in the family Rhamnaceae known by the common name Point Reyes ceanothus. It is endemic to California, where it is known from the coastline of the San Francisco Bay Area and areas north and south. It grows on seaside bluffs and the slopes of the coastal mountains. This shrub grows flat and spreading to erect, approaching two meters in maximum size. The evergreen leaves are oppositely arranged and up to 5 centimeters long, rounded to oval in shape. The edges are toothed, the teeth sometimes spine-tipped. The inflorescence is a small cluster of bright blue to purple flowers. The fruit is a horned capsule about 4 millimeters wide.
Ceanothus leucodermis, with the common names chaparral whitethorn or chaparral white thorn, is a species of shrub in the family Rhamnaceae. This Ceanothus is an importance browse for several types of ungulate, such as the mule deer and bighorn sheep, who prefer the new growth and shoots to the older, spiny parts.
Ceanothus maritimus, with the common name maritime ceanothus, is a species of shrub in the buckthorn family Rhamnaceae. It is endemic to San Luis Obispo County, California, where it is known from only a few occurrences in the vicinity of Hearst Ranch. It shares the same range as the similarly rare Ceanothus hearstiorum, growing on the coastal bluffs.
Ceanothus masonii is a species of shrub in the buckthorn family, Rhamnaceae, known by the common name Mason's ceanothus. It is endemic to Marin County, California, where it is known only from an area near Bolinas on the Point Reyes National Seashore. It grows in the coastal chaparral on the windblown bluffs..
Ceanothus pinetorum is a species of shrub in the family Rhamnaceae known by the common names Kern ceanothus and Coville ceanothus. It is endemic to the Sierra Nevada of California, where it is known only from the Kern Plateau, a section of the southern Sierra featuring wide meadows and ridges.
Ceanothus roderickii is a rare species of shrub in the family Rhamnaceae known by the common name Pine Hill ceanothus. It is endemic to western El Dorado County, California, where it grows in the chaparral and woodlands of the Sierra Nevada foothills, such as the Pine Hill Ecological Reserve. It is named after 20th century California flora explorer, botanist, and arboretum director Wayne Roderick.
Ceanothus sanguineus is a species of shrub in the family Rhamnaceae known by the common name redstem ceanothus. It is native to western North America from British Columbia to Montana to far northern California; it is also known from Michigan. It grows in temperate coniferous forest habitat in forest openings amidst the conifers. This is an erect shrub approaching 3 meters in maximum height. Its stem is red to purple in color, its woody parts green and hairless when new. The deciduous leaves are alternately arranged and up to about 10 centimeters long. They are thin, light green, oval, and generally edged with glandular teeth. The undersides are sometimes hairy. The inflorescence is a cluster of white flowers up to about 12 centimeters long. The fruit is a three-lobed smooth capsule about 4 millimeters long. This shrub is an important food plant for wild ungulates such as the Rocky Mountain Elk, it is browsed eagerly by many types of livestock, and the seed is consumed by many types of animals.
Ceanothus sonomensis, with the common name Sonoma ceanothus, is a rare species of shrub in the family Rhamnaceae. It is endemic to northern California.
Ceanothus verrucosus is a species of shrub in the family Rhamnaceae known by the common names wart-stem ceanothus, barranca brush, coast lilac and white coast ceanothus. It is endemic to northwestern Baja California and San Diego County, where it grows in coastal sage scrub and coastal succulent scrub habitats. It is considered a rare species north of the international border, as most of the valuable coastal land that hosts this plant in the San Diego area has been claimed for development. In California, several extant populations still remain scattered around the region, such as one protected at Torrey Pines.
Ribes hudsonianum is a North American species of currant, known by the common name northern black currant.
Vaccinium pallidum is a species of flowering plant in the heath family known by the common names hillside blueberry, Blue Ridge blueberry, late lowbush blueberry, and early lowbush blueberry. It is native to central Canada (Ontario) and the central and eastern United States plus the Ozarks of Missouri, Arkansas, southeastern Kansas and eastern Oklahoma.
