Texas barberry (Mahonia swaseyi)

At a glance

Lifecycle: Perennial (hardy)
Exposure: Full sun
Frost limit: −12.2 °C

Cultivation

Unlike most members of the genus, this species requires a dry, perfectly drained position in full sun, a gritty slightly acid soil is best. This species is not hardy in the colder areas of the country, it tolerates temperatures down to between -5 and -10°c. This plant has been recommended for improvement by selection and breeding as an edible fruit. Closely related to M. haematocarpa, differing mainly in having broadly ovate bracts up to 8mm long.

Propagation

Seed - best sown as soon as it is ripe in a greenhouse. It usually germinates in the spring[K]. 'Green' seed (harvested when the embryo has fully developed but before the seed case has dried) should be sown as soon as it is harvested and germinates within 6 weeks[K]. Stored seed should be sown as soon as possible in late winter or spring. 3 weeks cold stratification will improve its germination, which should take place in 3 - 6 months at 10°c. Prick out the seedlings when they are large enough to handle and grow them on in the greenhouse for at least their first winter. Plant them out in late spring or early summer and consider giving them some protection from the cold for their next winter. Division of suckers in spring. Leaf cuttings in the autumn.

Edible uses

Fruit - raw but more usually cooked in preserves. The roasted seed is a coffee substitute.

Medicinal uses

Berberine, universally present in rhizomes of Mahonia species, has marked antibacterial effects.

Habitat

Besides rocky streams in Texas. Endemic to the Edwards Plateau in Texas, where it grows on limestone ridges and canyons at elevations of 150-600 metres.

Native range

South-western N. America.