Key to Urtica
View taxon page for Urtica
(For a list of species in Urtica, use the above link.)
Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.
1. Annual 1–6(8) dm;
leaf 
Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).
blade 
Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.
18–40(90) mm;
inflorescence generally ± head- or spike-like, often <
petiole 
Leaf stalk, connecting leaf blade to stem; sometimes more or less indistinct.
, of
staminate and
pistillate flowers;
fruit deltate 
More or less equilaterally triangular, with the corners rounded or not.
..... U. urens 1' Perennial herb 5–30 dm; leaf blade 60–200 mm; inflorescence raceme- or panicle-like, generally > petiole, of staminate or pistillate flowers; fruit
ovate 
Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.
..... U. dioica 2. Non-stinging
hairs on
stem, leaf 0 to ±
dense, occasionally > 1 mm, those on
abaxial veins appressed 
Parallel or nearly parallel to and often in contact with surface of origin; used to describe the disposition of hairs, leaves, pedicels, etc.
; stem green
..... subsp. gracilis 2' Non-stinging hairs on stem, leaf dense, < 1 mm, those on abaxial veins
erect 
Upright; vertically oriented.
; stem gray-green
..... subsp. holosericea
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