''Ceanothus cyaneus'' is a species of flowering

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

in the genus ''

Ceanothus ''Ceanothus'' is a genus of about 50–60 species of Actinorhizal plant, 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 ceano ...

'' known commonly as the San Diego buckbrush and Lakeside ceanothus. This species is found in the

Peninsular Ranges The Peninsular Ranges (also called the Lower California province) are a group of mountain ranges that stretch from Southern California to the southern tip of the Baja California peninsula; they are part of the North American Coast Ranges, which ...

San Diego County, California San Diego County (), officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the fi ...

, and known from one occurrence in

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

. It is characterized by brilliant blue flowers, glossy green foliage, and is regarded as one of the most beautiful members of the genus.

Description

This plant is an open,

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

reaching less than 3 m in height. The stems are ascending to erect, with flexible, light-green twigs. The leaves are arranged alternately, with scale-like

stipule In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). Stipules are considered part of the anatomy of the leaf of a typical flowering plant, although in many speci ...

s. The leaf petiole is 2 to 6 mm long, while the leaf blade is 14 to 45 mm long and 15 to 20 mm wide. The leaves are shaped ovate to elliptic, colored dark green and smooth (lacking hair) on the upper surface of the leaf, while the bottom side of the leaf is colored pale green with

hairy Hairy may refer to: * people or animals covered in hairs or fur * plants covered in trichomes * insects covered in setae * people nicknamed "the Hairy" * Hairy (gene) See also * Hairies, a fictional people * Haerye ''Hunminjeongeum Haerye'' ...

veins. The margin of the leaves may be more or less

serrate Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied pr ...

, with 23 to 58 teeth. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

is 5 to 30 cm long, with deep or bright blue flowers. The fruit is 3 to 5 mm wide. The plants flower from April to June.

Characteristics

The twigs of this species are papillate (bearing small protuberances, papillae) not

thorn Thorn(s) or The Thorn(s) may refer to: Botany * Thorns, spines, and prickles, sharp structures on plants * ''Crataegus monogyna'', or common hawthorn, a plant species Comics and literature * Rose and Thorn, the two personalities of two DC Com ...

-like, and the leaf blade has a length that is less than twice the width. The flowers are a very distinctive brilliant blue. Compared to other local species like '' Ceanothus tomentosus'', this species has larger leaves and does not have the conspicuous black glands on the teethed edges of the leaf margin. The leaves are also almost glabrous, unlike both ''Ceanothus tomentosus'' and '' Ceanothus oliganthus''. The twigs are flexible, and not rigid like on '' Ceanothus leucodermis.''

Distribution and habitat

This species is distributed throughout part of

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

and has one historical occurrence in

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. In San Diego County, it is found in the inland

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...

on the

Peninsular Range The Peninsular Ranges (also called the Lower California province) are a group of mountain ranges that stretch from Southern California to the southern tip of the Baja California peninsula; they are part of the North American Coast Ranges, which ...

foothills near the communities of Lakeside and

Crest Crest or CREST may refer to: Buildings *The Crest (Huntington, New York), a historic house in Suffolk County, New York *"The Crest", an alternate name for 63 Wall Street, in Manhattan, New York *Crest Castle (Château Du Crest), Jussy, Switzerla ...

. This plant occurs in dense, almost impenetrable chaparral on

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock ...

and rocky, coarse sandy loams. In Baja California, a single historical collection is known from near the Cerro Coronel, in between

Tijuana Tijuana ( ,"Tijuana"
(US) and < ...

and La Mision.

Uses

This species was introduced into cultivation in California by

Theodore Payne Theodore Payne (June 19, 1872 - May 6, 1963), was an English horticulturist, gardener, landscape designer, and botanist. His best known work was done over his adult life in Southern California. Biography Payne was born at Manor Farm, Church Brampt ...

. It requires good drainage, must be kept dry during summer, and is not tolerant of frost.

References

External links

Jepson Manual TreatmentUSDA Plants Profile
cyaneus Flora of California Flora of Baja California Natural history of the California chaparral and woodlands Natural history of the Peninsular Ranges Natural history of San Diego County, California Taxa named by Alice Eastwood {{Rhamnaceae-stub