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..
perennial mostly glabrous herbs, with alternate petioled leaves and numerous, rather small, corymbose, discoid heads of white, yellowish or pinkish flowers, all tubular and perfect. Sap milky (at least in some species). Involucre cylindric or nearly so, its principal bracts • 5, in 1 series, equal, usually with a few short outer ones. Receptacle flat, not chaffy, with a fleshy projection in the center. Corollas with somewhat spreading 5-cleft limbs, the lobes usually with a mid-nerve. Style-branches conic or obtuse at the apex. Achenes oblong, glabrous. Pappus of copious white scabrous bristles. [Greek, referring to the central projection of the receptacle.]
About 30 species, natives of North and Central America. Besides the following, 4 others occur in the southern and southwestern parts of the United States. Type species: Mesadenia atriplici-folia (L.) Raf.
Leaves thin, reniform or fan-shaped, lobed, or angulate-dentate. Leaves green both sides, angulate-dentate.
1. M. reniformis.
Leaves glaucous beneath, green above, angulate-lobed.
2. M. atriphcifoha.
Leaves thick, green both sides, ovate or oval, entire, or repand.
3. M. tuberosa.
1753. 1804. Mesadeniareniformis Raf. New Fl.4: 79. 1836. M. rotundifolia Raf. New Fl. 4: 79. 1836.
Glabrous; stem angled and grooved, 40-10° high. Leaves thin, green both sides, coarsely angulate-dentate with mucronate-pointed teeth, the basal and lower reniform, long-petioled, sometimes 2° wide, the upper ovate or fan-shaped, mostly cuneate at the base, the uppermost small and oblong; heads numerous, mostly 5-flowered, about 2" broad, in large compound corymbs; involucre 3"-4" high, its bracts linear-oblong, obtuse or acutish, scarious-margined, with or without 1-3 minute outer ones.
Cacalia atriplicifolia L. Sp. Pl. 835. 1753.
Senecio atriplicifolius Hook. Fl. Bor. Am. 1: 332. 1833.
Mesadenia atriplicifolia Raf. New Fl. 4: 79. 1836.
Stem terete, glabrous and glaucous, 3°-6° high. Leaves thin, angulate-lobed, palmately veined, glaucous beneath, the lower and basal ones slender-petioled, sometimes 6' wide, the upper reniform, fan-shaped, or triangular with a nearly truncate base, the uppermost commonly small, lanceolate or oblong and entire; heads very numerous, about 1 1/2" broad, in large, loose compound corymbs; involucre 3"-4" high, its bracts linear-oblong, scarious-margined, with or without 1-3 minute outer ones.
In woods, New Jersey to Indiana. Minnesota, south to Florida, Tennessee, Missouri and Kansas. Recorded from Ontario. Called also wild caraway. July-Sept.
Cacalia tuberosa Nutt. Gen. 2: 138. 1818. Mesadenia plantaginea Raf. New Fl. 4: 79. 1836. Senecio Nuttallii Sch. Bip. Flora 27: 499. 1845. M. tuberosa Britton in Britt. & Brown, III. Fl. 3: 474. 1898.
Glabrous and green throughout; stem angled, stout, 2°-6° high. Leaves thick, strongly 5-9-nerved, the lower and basal ones oval, ovate, or ovate-lanceolate, obtuse or acutish, usually quite entire, but sometimes repand, long-petioled, narrowed at the base, or rarely subcordate, 4-8' long, 1'-3' wide; upper leaves ovate to oblong or cuneate-obovate, sessile or short-petioled, much smaller, sometimes toothed toward the apex; heads very numerous in a compound corymb, about 2" broad, mostly 5-flowered; involucre 3"-4" high, its bracts linear-oblong, obtuse or obtusish, scarious-margined.