Lamiaceae: Lamium amplexicaule

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Family Name

Lamiaceae

Common Name

Henbit deadnettle

Description

Lamium amplexicaule is an annual herbaceous plant growing 10 to 40 cm tall with a fibrous root system. The stems are square in cross-section, sprawling to ascending, and covered with fine hairs. Leaves are opposite, simple, and broadly ovate to orbicular with rounded or slightly lobed margins, measuring about 2 to 5 cm long and wide. Leaves are sessile, clasping the stem (amplexicaul). The leaf surfaces are hairy and rough to the touch. The inflorescence consists of whorls of tubular, two-lipped flowers arranged in leaf axils, flowering from early spring to early summer (March–June). The calyx is composed of five sepals fused into a tubular cup about 5 to 8 mm long, with five pointed lobes that are ovate-lanceolate in shape and covered with fine hairs. The corolla is bilabiate, about 1 to 1.5 cm long and 0.5 to 0.8 cm wide, with the upper lip forming a hood that is broadly ovate and rounded, while the lower lip is three-lobed with the central lobe being the largest and slightly notched. The petals are pink to purple with darker markings on the lower lip. The flowers have four stamens, two long and two short, and a superior ovary with a bifid style. The fruit is a schizocarp that splits into four nutlets. In South Dakota, Henbit deadnettle is an introduced species, native to Eurasia, commonly found in disturbed sites, lawns, gardens, fields, and roadsides statewide.

Additional Notes

Henbit is considered a weed but provides early nectar for pollinators in spring.