Plant Story--Henbit Deadnettle, Lamium amplexicaule

Every spring I notice henbit in my neighborhood, one of the early flowers of spring. It grows as a weed, slipping into the corners of lawns or the edges of driveways.

henbit, Lamium amplexicaule 

The USDA's map shows it as introduced all across North America (link), the invasive plant atlas is more detailed (link).

The USDA calls it henbit dead nettle. The scientific name is Lamium amplexicaule. Lamium is the genus after which the huge plant family that includes mint and culinary sage, Lamiaceae, is named. So henbit dead nettle is a mint--or mints are henbits--with square stems and the distinctive flower shape. Nettles, as in stinging nettle, Urtica dioica, are in a quite different family, the Urticaceae, nettle family. Dead nettle is a general English common name for these mints, many of which have leaves similar to nettles but do not sting. I suspect that if you live where stinging nettles are--they are rare on the Colorado Front Range--you quickly learn to recognize stinging nettles and so it is logical to name plants with similar leaves based on them. For me, it seems odd: henbit deadnettle isn't a nettle, it is a mint.

henbit dead nettle, not very big

Unlike many mints, henbit doesn't have much of an odor to its leaves. The species epithet, amplexicaulis, means "stem-clasping", describing the arrangement of the slightly hairy leaves. Leaves that circle the stem like henbit's are not very common among plants.

(The genus name Lamium is what the Romans called the plant; so you could say the meaning of Lamium is henbit or dead nettle.)

Henbit is a winter annual, a common lifestyle (life history in ecological jargon) around the Mediterranean where it is native. Winter annuals sprout in the fall, grow until it gets too cold, go dormant, and then restart growth as soon as temperatures allow in the spring. Then they flower, develop their seeds, and die by the heat of summer. Next fall, the cycle restarts.

The result is that roadsides and fallow fields across North America light up with flowering henbit quite early in the spring. The plants are rather small but collectively the purple flowers make a bright display.

After that, they mature their seeds and die. Each plant can easily produce 200 seeds. As a result henbit is considered a serious weed in a number of places worldwide. In your yard, since they are annuals, pulling them up before seed production will eliminate them. (Unless seeds from previous years linger in the soil, in which case you have to do that several years. I could not find anything on how long seeds last in the soil.) Henbit is a winter refuge for soybean cyst nematodes and an alternate host tomato yellow leaf curl virus, so is particularly undesirable with those crops.

It is one of a small group of plants that have two kinds of flowers. One set of flowers is big and showy, pollinated by bees and butterflies (technically, chasmogamous, outcrossed). The other flowers are small and self-pollinate without even opening (cleistogamous, closed). This works well for a weed. If conditions are good, insect pollinators will cross flowers of different plants, creating variation in the seeds that aids adaptation. But in bad conditions, the cleistogamous flowers make seeds, even if it is too cold or too dry for pollinators. As annuals, henbit plants don't get to try again next year. I notice it because of the bright purple chasmogamous flowers; if the plant has only the cleistogamous flowers, it just looks green.

The name henbit is a reference to the fact that henbit is edible and chickens like it. The whole plant is edible, to people as well as chickens. I haven't tried it; I don't want to eat weeds from the yards of people I don't know and so far my attempts to create a population in my back yard have failed. I transplanted more plants this year and will water them, hoping for a good seed crop so I harvest plantsnext spring. Foragers report henbit can be eaten fresh, cooked, or as a tea and is high in vitamins.

The flowers are attractive nectar and pollen sources for insects, including native bees.

Henbit is a European plant that is sometimes a problem to agriculture. On the plus side, you can eat it, animals can eat it, pollinators like it. It has pretty flowers, and, important to me, they make very nice, though small, cut flowers. Mostly, it is so small we all walk by it.

Comments and corrections welcome.

References
Brown, D. Purple dead nettle and hen bit: two common garden spring weeds. MSU Extension. link Accessed 4/10/20.
Edible wild foods. Henbit, Lamium amplexicaule. link Accessed 4/8/20.
The Foraged Foodie. Henbit and dead nettle: two edible, medicinal herbal weeds of early spring. link. Accessed 4/9/20.
Green, D. Henbit: top of the pecking order. EattheWeeds. link Accessed 4/8/20.

Kathy Keeler, A Wandering Botanist

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