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, often tufted, simple or branched herbs, with basal or alternate, entire leaves, and large long-peduncled discoid heads of purple, pink or white, glandular-pubescent flowers. Involucre hemispheric or broadly campanulate, its bracts in 1 or 2 series, herbaceous, narrow, nearly equal. Receptacle convex or at length conic, chaffy, the scales narrow, rigid, distinct. Rays none. Flowers all perfect and fertile, their corollas with a deeply 5-lobed or 5-parted campanulate limb and a slender tube. Anthers minutely sagittate at the base. Style-branches long, truncate. Achenes turbinate, 5-ribbed and 5-angled. Pappus of 5 or 6 acute or acuminate, ovate or lanceolate-deltoid, nearly entire scales. [Named for Humphrey Marshall, of Pennsylvania, botanical author.]
About 6 species, natives of the central United States. Type species: Marshallia Schreberi Gmel.
Leaves ovate, oval, or ovate-lanceolate, 3-nerved.
1. M. trinervia.
Leaves linear, lanceolate, or the basal spatulate, or obovate. Chaff of the receptacle linear; leaves linear; western.
2. M. caespi osa.
Chaff of the receptacle broader; leaves obovate to lanceolate; eastern.
3. M. grandiflora.
Athanasia trinervia Walt. Fl. Car. 201. 1788. Marshallia Schreberi Gmelin, Syst. 1208. 1791. Marshallia latifolia Pursh, Fl. Am. Sept. 519. 1814. Marshallia trinervia Porter, Mem. Torr. Club 5: 337. 1894.
Stem simple, or little branched, leafy to or beyond the middle, 1°- 2° high. Leaves thin, those of the stem ovate, oval or ovate-lanceolate, 3-nerved, acute or acuminate at the apex, narrowed to a sessile base, 2-3' long, 9"- 18" wide; heads 1/2' - 1' broad, corolla purplish; bracts of the involucre linear-lanceolate, acute, rigid; chaff of the receptacle subulate-filiform; pappus scales lanceolate-acuminate from a triangular base; achenes glabrous when mature.
In dry soil, Virginia to Alabama and Mississippi. May-June.
Stems usually tufted and simple, sometimes sparingly branched, leafy either only near the base or to beyond the middle, 8'-15' high. Leaves thick, mostly basal, faintly 3-nerved, linear or linear-spatulate, obtuse, sometimes 4' long and 3" wide, the upper ones linear, acutish, shorter; head about 1' broad, borne on a peduncle often 10' long; corollas pale rose or white; bracts of the, involucre linear-lanceolate, acute or acutish; chaff of the receptacle linear, or slightly dilated above; achenes villous on the angles; scales of the pappus ovate, acutish, equalling or longer than the achene.
Prairies and hills, Missouri and Kansas to Texas. May-June.
Marshallia grandiflora Beadle & Boynton, Biltmore Bot. Stud. 1: 7. 1901.
Stem simple, 1°- 2° high, leafy to above the middle. Lower and basal leaves obovate to oblong-lanceolate, tapering into petioles often as long as the blade, obtuse or obtusish; upper leaves lanceolate, sessile, or more or less clasping; florets slightly larger than those of M. trinervia, 7"- 10" long; achenes larger, 2"-2i" long, pubescent.
In moist soil, Pennsylvania to West Virginia and North Carolina. July-Aug.
Marshallia obovata (Walt.) Beadle & Boynton, a lower plant of the Southern States, with obovate or spatulate leaves mainly basal, is recorded as extending northward to southwestern Pennsylvania