Ferocactus Viridescens

''Ferocactus viridescens'' is a species of flowering plant in the cactus family Cactaceae. This rare barrel cactus is known by several common names, including coast barrel cactus, keg cactus and San Diego barrel cactus. Most of its native range in the United States is in San Diego County, California, where it is threatened by development, agriculture, and other alterations in its habitat. It is also found in northern Baja California, Mexico.

Description

''Ferocactus viridescens'' is a solitary barrel cactus, typically spherical, oblate, or nearly cylindrical, reaching heights of 10-30(-45)cm and diameters of 10-20(-35)cm. It has bright green flesh arranged into several 13 to 34 blunt ribs covered in arrays of long spines. The areoles are narrow elliptic to oval, 10-20 mm long, with brownish tomentum, bearing 10-19 spines per areole, including central and radial spines. The central spines are initially pink or yellowish, becoming duller with age, with the principal central spine measuring 30-50 cm long and 2-3(-5) mm broad. The 10-20 radial spines are similar to the centrals but smaller, 1-2 cm long.

Blooming from spring to early summer, the species produces infundibuliform flowers that are 2.5-5 cm long and 3-6 cm in diameter, with greenish-yellow or greenish perianth segments sometimes tinged with pink. The flower tube bears stamens almost to the top of the ovary, with yellow stigma lobes. The fruits are barrel-like, bright yellow (rarely reddish), with a pleasant acid taste, measuring 20-35 mm long and 15-25 mm across. They have a leathery skin and about 30 fimbriate-denticulate scales, dehiscent through a basal pore. The seeds are elongate-obovoid, minutely reticulate, and measure 1.6-1.8 mm long..

Taxonomy

John Torrey and Asa Gray first described ''Ferocactus viridescens'' as ''Echinocactus viridescens'' in 1840. The Latin specific epithet ''viridescens'' means "turning green". Nathaniel Lord Britton and Joseph Nelson Rose later reclassified the species under the genus ''Ferocactus'' in 1922.

''Ferocactus viridescens'' ssp. ''littoralis'' G.E.Linds., also known as the Santo Tomas coast barrel cactus, is found in a small area between Ensenada and Vicente Guerrero, Baja California. It has also been sighted slightly further south, along the coastline, near El Socorrito and Rancho Los Pinos.

Distribution

San Diego barrel cacti, as their name suggests, are found growing in the extreme south of Southern California—primarily in San Diego County—as well as across the U.S.-Mexico border into Baja California state, where it is found mostly along the coast, ranging south towards El Rosario and San Quintín. Beyond San Diego, California, the species has been observed as far north as San Clemente (Orange County) and Perris (Riverside County). Its preferred habitat varies, as it inhabits elevations ranging from sea level to 200 meters (656 feet), in coastal, mild-winter microclimates as well as warmer, inland areas that may experience autumn or winter frosts. It grows in sandy and gravelly soils with a generally high mineral content (but comparatively low amounts of organic matter).

Habitats where ''Ferocactus viridescens'' may be found include chapparal, arid hills, dry and grassy dunes, or rocky coastal bluffs and sun-baked cliffs; cacti especially thrive along the Californian and Mexican west coasts, as they experience significant fog cover (marine layer) throughout the year, notably in the mornings and evenings, allowing the plants to absorb sufficient moisture before the heat of the day. This habitat also gives ''Ferocactus viridescens'' an innate tolerance for salts and minerals that many botanical species simply cannot handle. The San Diego barrel cactus can also be found on shrub-covered hillsides, often at the crests of slopes, and in cobbles. Occasionally, it is found on the edges of vernal pools, sometimes in large numbers. This habitat, which is more moist compared to its usual xeric environment, is unusual for the plant, and may occur sporadically during years of excessive precipitation in the area.

Cultivation

This plant, which is hardy down to , must be grown under glass in temperate regions, though it may be placed outside in a sheltered spot in the warm summer months. It has gained the Royal Horticultural Society's Award of Garden Merit.

References

External links

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Jepson Manual TreatmentUSDA Plants ProfilePhoto gallery
{{Taxonbar, from=Q147469, from2=Q24691865, from3=Q96108196

viridescens
Cacti of the United States
var. viridescens
Flora of California
Natural history of the California chaparral and woodlands
Natural history of San Diego County, California