URTICACEAE 357 
wise glabrous, simple or branched at the base or above: leaf-blades thin, varying from 
suborbicular on the lower part of the stem, through ovate to lanceolate on the upper part of 
the stem, 1-4 cm. long, obtuse or acute, crenate-dentate, truncate or cordate at the base or 
the upper ones acutish ; petioles slender, 3-3 as long as the blades: flower-clusters shorter 
than the petioles : sepals oblong or those of the pistillate flowers oval, less than 1 mm. long, 
obtuse : achene ovoid, 1 mm. long, enveloped in the 2 accrescent sepals. 
In thickets, Kentucky to Arkansas, Florida and Texas. Spring and summer. 
3. Urtica Bréweri S. Wats. Perennial, stout, finely pubescent with somewhat curled 
hairs or glabrate except scattered bristle-like hairs. Stems 4-12 dm. tall, often branched : 
leaf-blades thin, lanceolate to narrowly oblong, 7-20 cm. long, acuminate, coarsely serrate 
with somewhat flaring teeth, rounded or subcordate at the base ; petioles about 4 as long as 
the blades : panicles about as long as the petioles : sepals oval, 1 mm. long, obtuse, densely 
hispid : achene ovoid, 1.2 mm. long, enveloped in the 2 accrescent sepals. 
On river banks, Wyoming to California, Texas and Mexico. Summer and fall. 
4. Urtica gracilis Ait. Perennial, slender, sparingly pubescent with stinging hairs. 
Stems erect, 6-18 dm. tall, angled, simple or sparingly branched above: leaf-blades thin, 
lanceolate to ovate-lanceolate, 6-15 cm. long, acuminate, rather coarsely serrate, the teeth 
often somewhat incurving, acute or obtuse at the base; petioles 4-} as long as the blade: 
panicles much longer than the petioles: sepals suborbicular, about 1 mm. long, densely 
puberulent : achenes ovoid, 1.2 mm. long, enveloped in the accrescent ovate sepals. 
On river banks and along fences, Nova Scotia to British Columbia, North Carolina and Louisiana. 
Summer and fall. 
5. Urtica dioica L.  Perennial, stoutish, densely bristly with stinging hairs. Stems 
erect, 6-13 dm. tall, simple or branched : leaf-blades ovate to ovate-lanceolate, 3-12 dm. 
long, acute or short-acuminate, coarsely serrate or sometimes incised, cordate at the base ; 
petioles 4-3 as long as the blades : panicles shorter than the petioles or about equalling them 
in length : sepals densely soft-pubescent, less than 1 mm. long, the outer obovate, the inner 
p nh : achene suborbicular, 1 mm. long, enveloped in the accrescent depressed orbicular 
sepals. 
In waste places, Nova Scotia to Minnesota, South Carolina and Missouri. Naturalized from 
Europe and Asia. Summer and fall. 
2. URTRICASTRUM Fabr. 
Perennial herbs (shrubs or trees in the tropics), armed with stinging hairs. Leaves al- 
ternate : blades often large and membranous, toothed : stipules distinct. Flowers monoecious 
or dioecious, mostly in axillary panicled or dichotomous cymes, the staminate with a 
perianth of 5 partially united sepals, 5 stamens, and a rudimentary ovary. Pistillate 
flowers with a perianth of 4 partially united somewhat unequal sepals and an oblique 
ovary: style subulate, becoming lateral. Achene oblique with a membranous or fleshy 
pericarp. Woop NETTLE. 
. 1l. Urticastrum divaricatum ( L.) Kuntze. Foliage bright green, bristly with sting- 
ing hairs. Stems 2-12 dm. tall, often flexuous : leaves alternate ; blades thin, ovate, oblong 
or elliptic, 5-20 em. long, acuminate, coarsely serrate or crenate-serrate, rounded or, rarely 
acutish at the base, glabrous or bristly, especially on the nerves ; petioles slender, 3 as long 
as the blades or longer : panicles slender, spreading, the lower staminate, the upper pistil- 
late : sepals oblong (in the staminate flowers) or suborbicular (in the pistillate), hyaline, 
or with hyaline margins : achene oblique, almost 3 mm. in diameter, the style lateral, about 
twice as long as the 2 accrescent sepals. [Laportea Canadensis Gaud. ] 
In thickets and rich woods, Nova Scotia to Minnesota, Florida and Kansas. Summer and fall. 
3. ADÍCEA Raf. 
Annual or perennial herbs, with pellucid watery tissues, destitute of stinging hairs. 
Leaves opposite : blades often 3-nerved or nearly nerveless, and transversely ridged or 
wrinkled, entire or toothed : stipules interpetiolar. Flowers monoecious or dioecious, in 
axillary panicled or congested cymes, the staminate with a perianth of 4 or rarely 2-3 
partially united sepals, the tube often cup-like, 4 or rarely 2-3 stamens and a rudimentary 
ovary. Pistillate flowers with a perianth of 3 partially united sepals and an equilateral 
ovary surrounded by 4 or rarely 2-3 staminodia : stigma tufted. Achene flattened, with 
a membranous pericarp. [Pilea Lindl] RICHWEED. CLEARWEED. 
Leaf-blades 2-10 mm. long, entire, transversely wrinkled or ridged. Wr 
" filiform : leaf-blades suborbicular or broadly oval, 2-4 mm. long. Lo herniarioides. 
Le seme not filiform : leaf-blades elliptic or oblanceolate, 5-10 mm. long. 2. A. microphylla. 
af-blades 3-10 em. long, toothed, not transversely roughened. 3. A. pumila. 
