Red Dead-Nettle › How to identify red dead-nettle
How to identify red dead-nettle
Red dead-nettle is easy to recognise once you know a few features. Use this checklist, and check every point before you decide what you have found.
Plant type and size
Red dead-nettle is an annual herb, so it grows from seed, flowers and dies within a year. Plants are usually 5 to 20 cm tall, though occasionally they reach about 40 cm in good conditions. They may be upright or sprawl a little, and they often grow in patches because they seed readily.
Stem
The stem is square in cross-section. Roll it between finger and thumb and you can feel the four corners. This is a key feature of the mint family (Lamiaceae), which includes dead-nettles, mints, sage and lavender. Stems are often tinged purple or red towards the top.
Leaves
- Arrangement: in opposite pairs, each pair at right angles to the pair below (a pattern called decussate).
- Shape: rounded to heart-shaped or triangular, with wavy or toothed edges, and a crinkled, hairy surface.
- Colour: green near the base, turning purplish towards the top of the stem, where leaves are small and tightly packed.
- Stalks: the leaves on the flowering stem have short stalks. This helps separate it from henbit, which has stalkless upper leaves.
- Feel: soft and slightly velvety, not stinging.
Flowers
The flowers are bright red-purple to pinkish-purple, tubular, with a hooded upper lobe and two lower lips. They grow in small clusters (whorls) in the angles between the upper leaves. Each flower is small, and the tube is shorter than that of henbit. The flowers are mostly visited by bees, and the pollen can be reddish.
Seeds and spread
After flowering the plant produces small nutlets, and the plant can set seed quickly, which is why it appears in disturbed ground each year. It can flower for much of the year, including during mild winter weather.
A step-by-step checklist
- Is the stem square?
- Are the leaves in opposite pairs?
- Do the upper leaves look purplish and crowded?
- Are the flowers pinkish-purple and hooded, in clusters among the upper leaves?
- Do the stem leaves have short stalks?
- Is there nothing that stings?
If you answered "yes" to all, it is probably red dead-nettle. If any answer is "no", compare with the plants on the lookalikes page.
Through the seasons
Seedlings often appear in autumn and early spring as pairs of rounded leaves. By late winter and early spring the plants are branching, and flowers appear whenever it is mild. In summer they can be shaded out by taller plants or die off in dry weather, and new plants often germinate again in autumn. Because it can flower in any month, a patch in a warm sheltered corner in January is not unusual.
Tips for identification
- Look at the plant in daylight, with a hand lens if you have one.
- Photograph the whole plant, a leaf pair and the flowers.
- Use a trustworthy field guide or a flora, and ask a local botanical society for help if you are unsure.
- Do not rely on a single phone app for anything you plan to eat.
For where to look, see habitat and flowering. For the full family, see related species.
Frequently asked questions
What does red dead-nettle look like?
A low plant with square stems, paired hairy leaves that turn purplish towards the top, and clusters of pinkish-purple hooded flowers among the upper leaves.
How tall does red dead-nettle grow?
Usually 5 to 20 cm tall, occasionally up to about 40 cm.
Is the stem of red dead-nettle round?
No. The stem is square in cross-section, a typical feature of the mint family.