Ceanothus

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Read about Ceanothus in the Standard Cyclopedia of Horticulture 

Ceanothus (ancient Greek name). Rhamnaceae. Ornamental woody plants grown for their profusely produced white, blue or pink flower-clusters.

Deciduous or evergreen shrubs or trees: lvs. alternate or sometimes opposite, short-petioled. serrate or entire, usually 3 - nerved, with small stipules: fls. perfect, small. 5-merous, in small umbels forming panicles or racemes; sepals often incurved, colored; petals clawed, spreading or recurved; filaments slender; disk annular; ovary partly adnate to the calyx-tube, 3-celled; style 3-cleft: fr. a 3-celled drupe, dry at length and separating into 3 one- seeded dehiscent nutlets.— Nearly 50 species in N. Amer., chiefly in the Pacific coast region.

These are free-flowering shrubs, some especially valuable for their late flowering period. Many of them are hardy only in the warmer temperate regions, but C. americanus, C. ovatus, and C. Fendleri are hardy North, while the numerous hybrids of C. americanus are only half hardy, and even if protected they are killed to the ground in the North, but the young shoots will usually flower the same season. The safest way, however, to have good free-flowering plants of these beautiful hybrids will be, in the North, to dig them up in fall, store them away in a frost-proof pit or cellar, and plant them out again in spring. Pruning of the late-flowering species will be of advantage; about one-half of last year's growth may be taken away. They grow in almost any soil, but best in a light and well-drained one, and most of the Californian species prefer a sunny position. Propagated by seeds sown in spring and by cuttings of mature wood in autumn, inserted in a cold- frame or greenhouse; softwood cuttings also grow readily if taken in early spring from forced plants. Sometimes increased by layers, and the varieties and hybrids by grafting on roots of C. americanus under glass in early spring; the cions must be fresh and with leaves, taken from plants kept in the greenhouse during the winter.


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Ceanothus
Ceanothus americanus flowers
Ceanothus americanus flowers
Plant Info
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Rosales
Family: Rhamnaceae
Genus: Ceanothus
L.

Species
See text
Ceanothus americanus (fruit left, flowers right)

Ceanothus L. is a genus of about 50–60 species of shrubs or small trees in the buckthorn family Rhamnaceae. The genus is confined to North America, with the center of its distribution in California but some species (e.g. C. americanus) in the eastern United States and southeast Canada, and others (e.g. C. coeruleus) extending 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.

Flowers of Ceanothus cuneatus, at Pinnacles National Monument, California

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

The Californian species are sometimes known as California-lilac, but not surprisingly, the species found elsewhere have other common names, e.g. New Jersey Tea for C. americanus (as its leaves were used as a black tea substitute during colonial times).[1] In garden use, most are simply called by their scientific names or an adaptation of the scientific name, e.g. Maritime Ceanothus for C. maritimus.

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).

Uses

Ceanothus species are used as food plants by the larvae of some Lepidoptera species including the bucculatricid leaf-miners Bucculatrix anaticula and Bucculatrix ceanothiella and the gelechiid Chionodes ceanothiella which all feed exclusively on the genus. Chionodes occidentella is a polyphagous species which has been recorded on Ceanothus.

Ceanothus is also a good source of nutrition for deer, specifically mule deer on the west coast. 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 [3].

Other uses of Ceanothus include medicinal and food sources of Native American Indians. Miwok Indians of California made baskets from Deer Brush branches [3]. C. integerrimus has been used by North American tribes to treat women who have suffered from a difficult birth [4]. Other Ceanothus species have also been used medicinally to treat high blood pressure and as a treatment to soothe mouth and throat ailments [1].

Several members of this genus, including Ceanothus americanus, form a symbiotic relationship with soil micro-organisms, forming root nodules which fix atmospheric nitrogen. This nitrogen is available to other adjacent plants, and may play an important role in forest regeneration as it creates nutrient-rich patches in forest habitats.

Propagation

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 [2]. Seeds are stored in duff in large quantities. It is estimated that there are about two million seeds per acre in forest habitats [3]. Seed are dispersed propulsively from capsules and, it has been estimated, can remain viable for about a hundred years.

Selected species

References

  1. University of Wisconsin Stevens Point Plant Database: Ceanothus americanus
  2. Plants for a Future: Ceanothus integerrimus.
  3. Fire Effects Information: Ceanothus integerrimus
  4. Moerman, D. (1988). Native American Ethnobotany. Timber Press, Oregon.

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