The opposite, coarsely saw-toothed leaves are 2 to 5 in. long on an erect, squarish, stem. Shipley Nature Center, Huntington Central Park, Huntington Beach, CA. 5-21-10. © Joan Avise.

Hoary (Stinging) Nettle

Urtica dioica ssp. holosericea

A densely hairy, generally monoecious perennial, 3 to 8 ft. tall in the summer, dying down to the ground in winter. It is common in damp moist places, usually near streams. It has widely spreading rhizomes and stolons, which are bright yellow as are the roots. Flowering June- September. Cultural uses.

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Flowers are clustered in pairs of racemes in axils; staminate clusters are loose, nearly as long as the leaves; pistillate clusters are denser and shorter; pistillate calyx deeply 4-parted of uneven lengths; no petals. Shipley Nature Center, Huntington Central Park, Huntington Beach, CA. 5-21-10. © Joan Avise.
The leaves and stems are very hairy with non-stinging hairs and also bear many stinging hairs (trichomes), whose tips come off when touched, transforming the hair into a needle that will inject several chemicals: acetylcholine, histamine, 5-HT (serotonin), moroidin, leukotrienes, and possibly formic acid. This mixture of chemical compounds cause a painful sting or paresthesia from which the species derives its common name, as well as the colloquial names burn nettle, burn weed, burn hazel (Wikipedia). Shipley Nature Center, Huntington Central Park, Huntington Beach, CA. 5-21-10. © Joan Avise.

Shipley Nature Center, Huntington Central Park, Huntington Beach, CA. 5-21-10. © Joan Avise.
Shipley Nature Center, Huntington Central Park, Huntington Beach, CA. 5-21-10. © Joan Avise.
Associations with insects
Host plant for the larvae of these butterflies:

Satyr Comma,
Polygonia satyrus
Red Admiral,
Vanessa atalanta
West Coast Lady,
Vanessa anabella
Painted Lady,
Vanessa cardui