This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Artemisia Absinthium L. Sp. Pl. 848. 1753.
Shrubby, finely canescent; stem much branched, 2°-4° high. Leaves 2'-5' long, 1-3-pinnately divided into numerous linear to obovate, obtuse lobes, the lower long-petioled, the upper short-petioled or sessile, the uppermost commonly linear and entire; heads numerous, yellow, racemose-paniculate, drooping, short-peduncled, 2"-2 1/2" broad; involucre hemispheric, its outer bracts linear, the inner much broader, scarious-margined; receptacle pilose-pubescent; central flowers fertile, the marginal ones pistillate, fertile or sterile.
In waste places, Newfoundland and Hudson Bay to Massachusetts, Pennsylvania, North Carolina, western Ontario, New York, North Dakota and Montana. Naturalized or adventive from Europe, mostly escaped from gard ens. Old English names, madderwort, mugwort, mingwort, warmot. Boys'-love. July-Oct.
Artemisia Abrotanum L. Sp. Pl. 845. 1753.
Perennial, somewhat shrubby; stem puberulent or glabrous, much branched, 2°-4° high, the branches short, erect or ascending. Leaves glabrous or somewhat pubescent, 1'-3' long, 1-3-pinnately parted into linear obtuse entire lobes about 1/2' wide, or the uppermost linear and entire, the lowest petioled; heads several-flowered, yellow, very numerous, nodding, racemose-paniculate, 2"-2 1/2" broad; involucre nearly hemispheric, pubescent, its outer bracts lanceolate, acute, the inner ones obovate; receptacle glabrous; central flowers fertile.
In waste places, Massachusetts to western New York, southern Ontario, and Nebraska. Adventive from continental Europe. Old English names, lad's-love, boys'-love, slovenwood, old-man, sweet benjamin.
Artemisia annua L. Sp. Pl. 847. 1753.
Annual, glabrous throughout, much branched, 2°-5° high. Leaves 2'-6' long, finely 2-3-pinnately dissected into very narrow short, obtuse lobes, the lower and basal ones slender-petioled, the upper sessile and less divided, but none of them entire; heads very numerous, about 1" broad, drooping, borne on very slender peduncles of about their own length or less; involucre hemispheric, glabrous, its bracts few, ovate to oblong; receptacle glabrous; flowers commonly all fertile.
In waste places, Ontario to New Hampshire, Virginia, West Virginia, Tennessee, Kansas and Arkansas, a bad weed in some places. Adventive or naturalized from Asia. Summer.