Some of the first green weeds to pop up in spring belong to two different families and are often confused. While it’s not of earth shaking importance you may want to know how to identify the difference between these sprawling goundcovers, ground ivy, (Glechoma hederacea) and one of the Lamiums, either deadnettle, (Lamium purpureum), hensbit, (Lamium amplexicaule), or Spotted deadnettle, (Lamium maculatum). These plants have similar looking leaves, flowers and growth habits.
Ground ivy has one very good distinguishing feature; it smells like mint when it’s cut or bruised. The plant crawls on the ground, and has green rounded to heart shaped leaves with a scalloped edge and prominent veins. Each leaf has a short stem, and they are joined in pairs opposite each other on the stem. The stems are square, and can be smooth or have short white hairs on them that point backward.
The flowers of ground ivy appear in the leaf joints at the end of stems in early spring and continue until warm weather. Flowering stems are shorter and more upright than other stems. The flowers are purplish blue and tubular with a flare of 2 lobes on the upper lip and 3 on the bottom. Some of the flowers do produce tiny tan seeds but the plant spreads more by rooting its stems than by seed.
Each joint of the ground ivy stem may root where it touches ground. In a season they can cover an amazing amount of space. The plants are also called creeping Charlie, gill over the ground or field balm. Ground Ivy likes damp, shady areas but can spread into full sun areas. It is a perennial plant and when covered with snow will remain green all winter. It is a frequent “weed” in lawns and gardens.
Ground Ivy is native to Eurasia where it has many uses and was probably brought here as an herbal remedy. Because it is high in Vitamin C it was used as a spring tonic, usually made into a pleasant tasting tea. The tea was said to be a cure for lead poisoning, common among painters in England. It was also used to brew beer, especially in France.
The lamiums come in 3 common species. Hensbit (L. amplexicaule) has leaves that may look similar to ground ivy, but on close inspection it can be seen that the leaves don’t have a stem and look like they encircle the square stem. Young leaves have fine white hairs on the surface. The stems of hensbit are reddish purple and are more upright than ground ivy. There is no mint smell when the foliage is broken.
The flowers of hensbit are tubular and lipped similar to ground ivy flowers. They appear in whorls on the end of stems between the leaf layers. They are a bit larger and showier than ground ivy flowers and range in color from pale pink to purple. Heaviest flowering is in early spring, but cool periods, especially in late summer will bring more blooming. These flowers will produce numerous seeds.
Hensbit is an annual and while the stems may root, it spreads by seed. Seedlings may come up at any time its mild and some survive the winter as seedlings to bloom in spring. It likes sunnier areas than ground ivy but can grow in partial shade.
Hensbit’s close relative is purple deadnettle, (L. purpureum). Purple deadnettle has leaves that are more pointed than hensbit and the upper leaves on a stem have short stems. Leaves further down the stems may appear to circle the stem much like hensbit. Leaves and stems have white hairs but the hairs do not cause itching like other nettles. The end of each stem is packed with a whorl of leaves that have a reddish purple color, which gives purple deadnettle its name. The stems are also reddish.
Purple deadnettle flowers are smaller, lighter in color and more hidden under the leaves than hensbit. They are shaped like hensbit flowers. This plant is also an annual that spreads by seed. It can look quite showy in the lawn or garden in cool times of the year. It likes sunny areas.
Purple deadnettle and hensbit are both native to Eurasia. They are considered edible and are eaten in spring salads. Both of these plants are important sources of nectar and pollen for bees in the spring. They should be tolerated in wilder areas. But you may want to prevent large patches from forming where animals like cattle and sheep may graze as they can cause a condition called staggers.
The other lamium one may encounter in a garden or lawn is actually cultivated as a ground cover but sometimes escapes. Spotted deadnettle, (L. maculatum) is much like purple deadnettle, but the leaves are attractively spotted with white. You may know it as White Nancy. Several color variations exist, some more golden leaved, some silvery leaved as well as the spotted variation. Numerous varieties are on the market. These plants are perennial and make good ground covers in partially shaded areas. They flower sporadically through the summer. They spread by runners, but can become invasive. They too, are native to Eurasia.
Since one mans weed is another man’s flower some people enjoy growing all of the plants listed above. Purple deadnettle is often mistaken for a perennial flower in gardens because it’s pretty and leaving ground ivy in the lawn makes it smell nice when it’s mowed. But now you know what these plants look like it’s your choice whether to remove or save them.
Here are some additional articles you may want to read.
Crown Vetch, friend or foe
How to identify evergreens
Shamrocks, 4 leaved clovers and oxalis
You can read the authors weekly garden blog here.