Red Dead-nettle, Lamium purpureum

Purple dead-nettle is a weedy winter annual (sometimes a summer annual) in the mint family (Lamiaceae). It is usually considered a common lawn weed and originates from Europe and Asia. The common name “purple dead-nettle” refers to the resemblance of Lamium leaves to those of the nettle family (Urticaceae), members of which often have stinging hairs. Lamium does not have stinging hairs (and is, hence, “dead”). The species epithet is Latin for “purple,” which describes the flowers and the subtending leaves.

Purple dead-nettle prefers full sun or light shade and moist, fertile soil. It will, however, tolerate sandy or clay soils. This plant develops quickly during the cool weather of spring. It is typically viewed as a common garden weed, flowering at any time of the year, with seed germinating whenever the weather is mild.

It is a low-growing weed, maturing up to 2½ feet tall, but usually shorter, with no branches. The leaves are opposite and decussate, meaning that a pair of leaves emerges from each node, and each pair is rotated 90° from the pair of leaves immediately below or above. Young leaves subtending flowers are often suffused with purple. The blooming period for the bright reddish purple, ½-inch flowers is usually mid- to late spring and lasts about six weeks, although plants that germinate in the summer may bloom during the fall. The upper surface of each leaf has a reticulated network of indented veins, creating a wrinkly appearance. 

It can be found in lawns, along roads, gardens and meadows. It is often confused with henbit (Lamium amplexicaule), which can grow with purple dead-nettle. Henbit can be distinguished by its nearly circular, stemless leaves and showier flowers.

This plant occasionally forms dense colonies by reseeding itself. It can become weedy and is often found in moist fallow fields, ditches and drainage canals, gardens and nursery plots, weedy edges of woodlands and various kinds of waste ground. It prefers degraded sites with a history of disturbance. On the plus side, the flowers are visited by bees.

Diseases, Insect Pests, and Other Plant Problems: The foliage is little bothered by disease and insect pests. The Clemson Cooperative Extension Home and Garden Information Center has a factsheet on controlling purple dead-nettle in lawns and gardens.