''Ceanothus cyaneus'' is a species of flowering shrub in the genus ''

Ceanothus ''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"' ...

'' known commonly as the San Diego buckbrush and Lakeside ceanothus. This species is found in the Peninsular Ranges of San Diego County, California, 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 shrub 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 stipules. 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 veins. The margin of the leaves may be more or less serrate, with 23 to 58 teeth. The inflorescence 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-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 ''Ceanothus tomentosus'', with the common name woollyleaf ceanothus, is a species of shrub in the family Rhamnaceae. It is characterized by pale-blue to deep blue flowers and wooly leaves. It is native to California and Baja California, having an ...

'', 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 ''Ceanothus oliganthus'' is a species of shrub in the family Rhamnaceae known by the common name hairy ceanothus or hairy-leaf ceanothus.Flowering Plants of the Santa Monica Mountains, Nancy Dale, 2nd Ed., 2000, p. 167 The variety of this specie ...

''. The twigs are flexible, and not rigid like on '' Ceanothus leucodermis.''

Distribution and habitat

This species is distributed throughout part of San Diego County, California 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 U.S. state, states, a Washington, D.C., federal district, five ma ...

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 Guate ...

. 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 Mediterrane ...

on the Peninsular Range foothills near the communities of

Lakeside Lakeside or Lake Side may refer to: Places Australia * Lakeside College, Pakenham, Victoria * Lakeside Joondalup Shopping City, Joondalup, Western Australia * Lakeside, near Reservoir, Victoria * Lakeside International Raceway, Pine Rivers, Quee ...

and Crest. This plant occurs in dense, almost impenetrable chaparral on igneous rock and rocky, coarse sandy loams. In Baja California, a single historical collection is known from near the Cerro Coronel, in between Tijuana and La Mision.

Uses

This species was introduced into cultivation in California by Theodore Payne. 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