5. Urtica L. (nettle)
Plants annual or
perennial (but then sometimes flowering the first year), armed with sparse to
dense, long, stinging hairs, often also with sparse to dense, shorter, finer,
nonstinging hairs, more or less taprooted or with rhizomes. Stems erect or
ascending to more or less spreading with ascending tips, unbranched or branched.
Leaves opposite, short- to more commonly long-petiolate, stipulate. Leaf blades
lanceolate to ovate, elliptic, or somewhat heart-shaped, variously angled to
rounded, truncate, or shallowly cordate at the base, short-tapered to tapered
at the tip, the margins variously toothed, more or less with 3 main veins,
sometimes appearing weakly palmately veined; cystoliths more or less rounded or
less commonly linear. Inflorescences axillary, small clusters, these often
arranged in panicles or occasionally dense spikelike racemes, the staminate
flowers variously in the same inflorescences as the pistillate ones or in
different inflorescences on the same or different plants. Staminate flowers
with 4 sepals, these 0.8–1.5 mm long, cupped around the stamens. Stamens 4.
Pistillate flowers with 4 free sepals, the calyx consisting of 2 smaller,
spreading sepals, alternating with 2 larger sepals, these loosely cupped around
but not fused to the ovary and fruit. Style absent, the stigma capitate
(papillose and appearing bushy, not persistent at fruiting), the stigmatic
region linear. Fruits 1–2 mm long, flattened, ovate or ovate-elliptic in
outline, tan to brown, glabrous, the surface often appearing finely pebbled.
About 45 species, nearly worldwide.
Stinging hairs
are relatively sparse in the taxa of Urtica native to Missouri and care
must be taken not to miss these during identification of the genus. Steyermark
(1963) noted that the young herbage of nettle species is sometimes boiled and
eaten as a vegetable.