Lamium amplexicaule L.

Henbit

Lamium amplexicaule plant2

Family - Lamiaceae

Habit - Taprooted annual forb.

Stems - Ascending to erect, to 35 cm tall, often multiple from base, purplish basally, greenish above, 4-angled, hollow, usually pubescent with retrorse hairs.

Lamium amplexicaule stemStem and node.

Leaves - Opposite, lowest leaves petiolate. Petioles to 2 cm long. Blades unlobed or 3-lobed, to 2 cm long and broad, rotund to reniform, pubescent, the margins bluntly toothed or scalloped. Upper leaves appear clasping or perfoliate.

Lamium amplexicaule leaves

Inflorescences - Well-separated axillary clusters in the apical 1/2 of the stem, lacking bractlets, with 4-12 flowers per node. Cleistogamous flowers often produced.

Lamium amplexicaule inflorescenceInflorescence.

Flowers - Calyces 5-7 mm long, the tube and lobes densely bristly-hairy, the lobes shorter than to slightly longer than the tube. Corollas (except in cleistogamous flowers) 10-20 mm long, the outer surface sparsely to more commonly densely hairy, with a very dense patch of usually longer, darker hairs on the upper lip, the upper lip 3-5 mm long, rounded to shallowly notched at the tip, pinkish purple, rarely entirely white, the lower lip 1.5-3.0 mm long, usually lighter pink or white, with purple spots or mottling, rarely entirely white, the lateral lobes reduced to small convexities along the lip margin, the central lobe obcordate. Stamens 4, didynamous, fused to the base of lower lip, included under the upper lip. Filaments white, 4-5 mm long, slightly pubescent near the base. Anthers purplish, 1 mm long. Style 1.8 cm long, white, glabrous. Stigma 2-lobed. Ovary 4-parted, light green, 1.7 mm long, glabrous. Divisions of ovary shaped like pie-pieces when viewed from above.

Lamium amplexicaule calycesCalyces (fruiting).

Lamium amplexicaule flowersFlowers.

Lamium amplexicaule flowers2

Fruits - Dry schizocarps, separating into 2-4 nutlets, these 1.5-2.5 mm long, obovoid, truncate at the tip, often with thickened angles, with 2 flat sides and a rounded dorsal face, the surface light brown to grayish brown or olive brown, often with lighter mottling, finely pebbled, glabrous.

Flowering - February - November.

Habitat - Waste ground, lawns, cultivated fields, pastures, roadsides, railroads.

Origin - Native to Eurasia and Africa.

Lookalikes - Lamium purpureum.

Other info. - This aggressive little plant has spread throughout Missouri and nearly all of North America. The plant is tolerant of sun or shade, heat or cold. In cultivated areas that get tilled regularly, the plant can form vast seas of pink in the spring. The plant can grow from small pieces of its stem so chopping the plant only helps it spread. It also grows well from seed.

There is a report that livestock in Australia develop neurological problems ("staggers") after grazing on henbit; however, this does not seem to occur in the U.S., or in areas where henbit is native.

Photographs taken in Brown Summit, NC., 2-4-03, and at Rock Hill Park, Boone County, MO., 3-27-04 (DETenaglia); also near Labadie, Franklin County, MO, 4-6-2008 and 4-10-2019, and near Treloar, Warren County, MO, 4-23-2014 (SRTurner).


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