Burning nettle (Urtica urens)
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Burning nettle, an annual broadleaf plant, behaves as a winter annual in the interior valleys of California and grows year-round on the coast, where it is especially troublesome. Burning nettle is found througout much of California, to 9800 feet (3000 m), except for the Klamath Ranges, upper elevations of the Cascade Range, and deserts. It inhabits agricultural lands and other disturbed sites. Skin contact with the hairs of this plant usually causes a burning or stinging sensation for several minutes. This may be followed by a longer period of itching or numbness. A related species, stinging nettle, Urtica dioica, also causes a burning or stinging sensation.
Crop fields, orchards, vineyards, gardens, ditches, nurseries, roadsides and other disturbed, unmanaged places.
Cotyledons (seed leaves) are rounded, smooth edged and have a small notch at the tip. The first true leaves are oval, sparsely hairy, have distinctly toothed edges, sit atop short stalks, and are opposite to one another along the stem.
Mature plants are 5 to 24 inches (12.5—60 cm) tall, with square stems that branch from the base. Most of the plant's stinging hairs are located on the stems, leaf stalks, and lower surface of leaves. Leaves are elliptical to egg shaped, have toothed edges, and besides stinging hairs, have short non-stinging hairs, and often minute glands. Burning nettle has a slender taproot, often with many lateral roots. The related stinging nettle plant is taller and its leaves are less rounded than those of burning nettle.
Flowers bloom from January through April, but year-round in milder coastal climates. Small greenish white flowers cluster in the junction where the leaf stalk and stem join.
Fruits are tiny, less than 1/12 of an inch (2 mm), smooth, egg shaped, and contain a single seed.
Reproduces by seed.
Related or similar plants
- Stinging nettle, Urtica dioica ssp. holosericea