Arbutus

Arbutus canariensis.

Arbutus is a genus of plants in the family Ericaceae with about 11 accepted species, out of more than 100 described, of trees and shrubs native to temperate regions. the Mediterranean, Western Europe and North America. Several of the species are widely cultivated as ornamental plants outside of their natural habitat.

• Note: Some species of genders Epigaea, Arctostaphylos and Gaultheria were previously classified into gender Arbutus.

Description

They are trees to shrubs; bark falling off in large flakes, remaining only on old parts of trunks. Alternate, perennial, petiolate, coriaceous leaves, eucamptodrome venation, entire or finely serrated margins. Terminal inflorescences in grouped racemes; flower bracts early hardened; pedicels continuous with calyx; bracteoles 2, basal. Flowers 5-mer, scentless, aestivation imbricated; free chalice wolves; corolla urceolate, constricting towards the middle and inflating simultaneously; stamens 10, equal; filaments distinct, equal, expanded below to a swollen downy base, the connective sometimes prolonged to a sagitted membranaceous wing extending above anther apex; spurred anthers, the apex dehiscent by subterminal elliptical pores, with disintegrating tissue; viscine stringless pollen; superior ovary. Fruits in berries, rough-tuberculate, glabrous or hairy; brown seeds, partially embedded in a fleshy placenta.

Taxonomy

The genus was described by Charles Linnaeus and published in Species Plantarum 1: 395. 1753.

Genetics

A recent study analyzing the ribosomal DNA of Arbutus and its related genera suggests that species from the Mediterranean Basin are not very closely related to North American species and that the split between the two groups occurred between the Paleogene and Neogene periods.

Species

Main species

Old World

• Arbutus andrachne. Southeast Europe and Southwest Asia.
• Arbutus canariensis Veill.. Canary Islands.
• Arbutus unedo L.. It was spread throughout the Mediterranean region, including its islands and also west of France and west Ireland as well as south to the Algarve in Portugal. Also native to Ukraine and the Canary Islands
• A. unedo and A. andrachne are hybridized naturally where their distribution areas coincide; the hybrid has been called Arbutus × andrachnoides (no. A. × hybridaor A. andrachne × unedo), inheriting traits from both species of origin, although the fruits are not usually born freely, and as a hybrid it is unlikely that it actually breeds from seeds.

New World

• Arbutus arizonica (A.Gray) Sarg.. New Mexico, Arizona and Eastern Mexico to the south to Jalisco.
• Arbutus menziesii Pursh. West coast of North America from South British Columbia to Central California, on the western slopes of Sierra Nevada and the Pacific Coastal Chain Mountains.
• Arbutus xalapensis Kunth (no. A. texana, A. peninsularis and A. glandulous). Texas, New Mexico and Mexico.

Other species accepted

• Arbutus × androsterilis M.Salas " al.
• Arbutus munsis S.González
• Western Arbutus McVaugh & Rosatti
• Arbutus tessellata P.D.Sørensen

Complete list of all the taxa described, accepted and synonyms in "The Plant List"

Ecology

Members of this genus are eaten by some species of Lepidoptera, including the emperor butterfly.