Ceanothus

Ceanothus
Ceanothus americanus flowers
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Rosales
Family:	Rhamnaceae
Genus:	Ceanothus L.[1]
Species
See text

Ceanothus L. /ˌsiːəˈnoʊθəs/^[2] is a genus of about 50–60 species of nitrogen-fixing^[3] shrubs or small trees in the family Rhamnaceae. Common names for members of this genus are California lilac, wild lilac, and soap bush.^[4] "Ceonothus" comes from a Greek word meaning "spiny plant".^[4]

The genus is confined to North America, with the center of its distribution in California. Some species (e.g. C. americanus) are found in the eastern United States and southeast Canada, and others (e.g. C. coeruleus) extend as far south as Guatemala. Most are shrubs 0.5–3 m tall, but C. arboreus and C. thyrsiflorus, both from California, can be small trees up to 6–7 m tall. The name is derived from the Greek word κεανοθος (keanothos), which was applied by Theophrastus (371-287 BC) to a spiny Old World plant believed to be Cirsium arvense.^[5][6]

Description

Ceanothus arboreus illustrating the three parallel leaf veins characteristic of plants in this genus

Growth pattern

The majority of the species are evergreen, but the handful of species adapted to cold winters are deciduous. The leaves are opposite or alternate (depending on species), small (typically 1–5 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.^[7]

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.^[8]

Flowers and fruit

Flower of Ceanothus fendleri

The flowers are white, greenish–white, blue, dark purple-blue, pale purple or pink, maturing into a dry, three-lobed seed capsule.

The flowers are tiny and produced in large, dense clusters. A few species are reported to be intensely fragrant almost to the point of being nauseating, and are said to resemble the odor of "boiling honey in an enclosed area." The seeds of this plant can lie dormant for hundreds of years, and Ceanothus species are typically dependent on forest fires to trigger germination of their seeds.^[8]

Fruits are a hard, nut-like capsule.^[4]

Ecology

Ceanothus is a good source of nutrition for deer, specifically mule deer on the west coast of the USA. 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.

Distribution

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 up to 9,000 feet. 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.

Ceanothus velutinus is the most common member of this genus and is widespread throughout North America.^[8]

Cultivation

Flowers of Ceanothus cuneatus, at Pinnacles National Park, California

Many species are popular garden ornamental plants, and dozens of hybrids and cultivars have been selected, such as 'Flexible ceanothus', Ceanothus × flexilis Greene ex McMinn (C. cuneatus × C. prostratus).

The following cultivars and hybrids have gained the Royal Horticultural Society's Award of Garden Merit:-

(See also C. arboreus and C. thyrsiflorus).

Propagation

California Lilac (Ceanothus integerrimus) in Yosemite, 2005

Propagation of ceanothus is by seed, following scarification and stratification. Seeds are soaked in water for 12 hours followed by chilling at 1 °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.

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 made baskets from ceanothus branches. C. integerrimus has been used by North American tribes to ease childbirth.

Names

The Californian species are sometimes known as California lilac, but species found elsewhere have other common names, such as New Jersey tea for C. americanus (as its leaves were used as a black tea substitute during colonial times).^[17] 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.

Selected species

Formerly placed here

• Adolphia infesta (Kunth) Meisn. (as C. infesta Kunth)
• Colubrina arborescens (Mill.) Sarg. (as C. arborescens Mill.)
• Colubrina asiatica (L.) Brongn. (as C. asiaticus L.)
• Colubrina elliptica (Sw.) Brizicky & W.L.Stern (as C. reclinata L’Hér.)
• Noltea africana (L.) Endl. (as C. africanus L.)^[19]

See also

• California chaparral and woodlands

Notes

Wikimedia Commons has media related to Ceanothus.

Wikispecies has information related to: Ceanothus

References

1. University of Wisconsin–Stevens Point Plant Database: Ceanothus americanus
2. Moerman, D. (1988). Native American Ethnobotany. Timber Press, Oregon.