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..
[Liatris Schreb. Gen. Pl. 542. 1791.] Erect perennial herbs, usually from a globular tuber, simple or little branched, with alternate, entire, narrow 1-5-nerved leaves, and spicate or racemose discoid heads of rose-purple or white flowers. Involucre oblong, ovoid or subhemispheric, its bracts imbricated in several series, the outer shorter. Receptacle flat, or slightly convex, naked. Corolla regular, its tube slender, its limb 5-lobed or 5-cleft. Anthers obtuse at the base. Style-branches elongated, obtuse or flattened at the apex. Achenes 10-ribbed, slender, tapering to the base. Pappus of 1 or 2 series of slender barbellate or plumose bristles. [Latin, fringed, from the appearance of the heads.]
About 35 species, natives of eastern and central North America, known as Blazing Star, or Button Snakeroot from the globular tubers. Type species: Serratula squarrosa L.
* Bracts of the involucre acute, acuminate or mucronate. Involucre cylindric, or turbinate, 15-60-flowered, its base rounded. Bracts with lanceolate spreading rigid tips.
1. L. squarrosa.
Bracts mucronate, closely appressed.
2. L. cylindrica.
Involucre oblong, or narrowly campanulate, 3-6-flowered. Inner bracts with prolonged petaloid tips.
3. L. elegans.
Bracts all acute, mucronate or acuminate.
Bracts appressed; pappus-bristles very plumose. Leaves 1"-2" wide: spike usually leafy below.
4. L. punctata.
Leaves less than 1" wide: spike mostly naked.
5. L. acidota.
Tips of the bracts spreading; pappus-bristles barbellate.
6. L. pycnostachya.
** Bracts of the involucre rounded, obtuse or acutish. Involucre hemispheric, 1/2'-1' broad, 15-45-flowered; heads peduncled.
7. L. scariosa.
Involucre oblong, 2 -4 broad, 5-15-nowered. Bracts obtuse, rounded.
Involucre rounded at base; bracts usually not punctate; heads mostly sessile.
8. L. spicata.
Involucre narrowed at base; bracts usually punctate; heads peduncled.
Leaves, even the lower, narrowly linear; involucre narrowly obovoid, 5"-6" high.
9. L. graminifolia.
Lower leaves linear-oblong; involucre broadly obovoid, 6"-7" high.
Bracts acutish, punctate.
II. L. Smallii.
Serratula squarrosa L. Sp. Pl. 818. 1753. Lacinaria squarrosa Hill, Hort. Kew. 70. 1769. Liatris squarrosa Willd. Sp. Pl. 3: 1634. 1804. Liatris intermedia Lindl. Bot. Reg. pl. 948. 1825. Lacinaria squarrosa intermedia Porter, Mem. Torr. Club 5: 314. 1894. Liatris squarrosa var. intermedia DC. Prodr. 5: 129.
Usually stout, 1/2°-2° high, pubescent or glabrous. Leaves narrowly linear, rigid, sparingly punctate, 3'-6' long, 1"-2 1/2" wide; heads sessile or short-peduncled, 15-60-flowered, usually few, or sometimes solitary. 1/2'-1 1/2' long, 4"-8" thick; bracts of the involucre imbricated in 5-7 series, lanceolate, rigid, acuminate, glabrous or pubescent, their tips more or less spreading when old; flowers purplej pappus very plumose.
In dry soil, western Ontario to Pennsylvania, Virginia, Florida, South Dakota, Nebraska and Texas. Called also rattlesnake-master. Races differ in pubescence and in size of the heads. June-Sept.