''Ceanothus cyaneus'' is a species of flowering

shrub A shrub or 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 by their multiple ...

in the genus '' Ceanothus'' known commonly as the San Diego buckbrush and Lakeside ceanothus. This species is found in the Peninsular Ranges of

San Diego County, California San Diego County (), officially the County of San Diego, is a county (United States), county in the southwest corner of the U.S. state of California, north to its Mexico-United States border, border with Mexico. As of the 2020 United States Cen ...

, and known from one occurrence in

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

. 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 Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

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 (botany), petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part ...

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 veins. The margin of the leaves may be more or less serrate, with 23 to 58 teeth. The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

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 thornlike, 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 (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and has one historical occurrence in

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

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

chaparral Chaparral ( ) is a shrubland plant plant community, community found primarily in California, southern Oregon, and northern Baja California. It is shaped by a Mediterranean climate (mild wet winters and hot dry summers) and infrequent, high-intens ...

on the Peninsular Range foothills near the communities of Lakeside and Crest. This plant occurs in dense, almost impenetrable chaparral on

igneous rock Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...

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

Tijuana Tijuana is the most populous city of the Mexican state of Baja California, located on the northwestern Pacific Coast of Mexico. Tijuana is the municipal seat of the Tijuana Municipality, the hub of the Tijuana metropolitan area and the most popu ...

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