Species

As of December 2023^[update], accepted species are:^[2][14]

Species names with uncertain taxonomic status

The status of the following species is unresolved:^[14]

Hybrids

The following hybrids have been described:^[14]

Hybrid names with uncertain taxonomic status

The status of the following hybrids is unresolved:^[14]

Growth pattern

The majority ^{[citation needed]} 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.^[16]

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.^[17]

Flowers and fruit

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 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]} The seeds of this plant can lie dormant for hundreds of years,^{[citation needed]} and Ceanothus species are typically dependent on forest fires to trigger germination of their seeds.^[17]

Fruits are hard, nutlike capsules.^[8]

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 hybrids and cultivars have been selected, such as flexible ceanothus, Ceanothus × flexilis (C. cuneatus × C. prostratus).^{[citation needed]}

Royal Horticultural Society's Award of Garden Merit cultivars

The following cultivars and hybrids have gained the Royal Horticultural Society's Award of Garden Merit (as of 2017^[update]):^[18]

Other cultivars available include:-

There are also more cultivars and hybrids of Ceanothus arboreus, Ceanothus griseus horizontalis (groundcovers), and Ceanothus thyrsiflorus in the nursery trade.

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.^[37]