General: Horehound (Marrubium vulgare) is a non-native shrub introduced into this country from Europe. It is now widespread, but it isn't terribly invasive, and the weed can be controlled by digging up the shallow roots.

The shrub grows upright to spreading with round, crinkly leaves. The flowers are in ball-like clusters in the leaf axils, and when dried, persist on the plant. The stems are square in cross-section.

Horehound is an uncommon component of vegetation communities in dry, well-drained sandy and gravelly areas on desert flats, bajadas, and moderate slopes in the lower mountains in the Lower Sonoran (Creosote-Bursage Flats) and Upper Sonoran (Mojave Desert Scrub) life zones. Look for this plant in disturbed areas such as around cattle operations and parking areas.

Family: Mint (Lamiaceae).

Other Names: White Horehound

Plant Form: Upright, spreading shrub.

Height: To about 2 feet.

Stems: Upright, spreading, square.

Leaves: Roundish with toothed edge, crinkly texture, hairy.

Flowers: Inflorescence axillary. Flowers in clusters. Corolla white, two lipped, upper lip two lobed, lower lip three lobed.

Seeds: Nutlet.

Habitat: Disturbed and overgrazed sites desert flats, canyons, and lower desert mountains.

Elevation: To about 2,000 feet.

Distribution: Worldwide, but desert mountains around Las Vegas.

Comments: This is a weed species that should be removed when found. Dig it up and bag the plant to prevent spreading the seeds.