This section is from the book "Class-Book Of Botany USA&Canada", by Alphonso Wood. Also available from Amazon: Class-Book Of Botany.
2 H. debilis Nutt. Decumbent, slender; lvs. ovate, serrulate, petiolate, mostly alternate; hds. small, solitary, pedunculate ; scales narrow, slender-pointed; ach. pubescent. - (J) Fla., La. (Not within our limits ?). Sts. 1 to 2f long. Hds. half an inch diam. Rays about 12.
3 H. Radula Torr. & Gr. Erect, hirsute, simple, bearing a single head; lvs. sessile or nearly so, roundish obovate or ovate, obtuse, opposite, crowded below; scales and pales lanceolate, acuminate, erect, dark purple; rays 7 to 10, rarely none. -Ц Barrens, Ga., Ala., Fla. St3. often clustered, 1 to 3f high. Lvs. very rough on the upper surface. Hds. near 1' diam., disk dark purple. Aug., Sept † (Rudbeekia, Ph.)
4 H. heterophyllus Nutt. Slightly hispid, slender, bearing a single head; lvs. opposite, entire, subsessile, the lower oval, upper linear-lanceolate, scales acuminate, erect, ciliate; pales acute; rays 12 to 18. - Ц N. Car. to Fla. and La. St. 1 to 2f high. Hds. 6 ' diam., rays expanding 2 1/2'. Aug., Sept.
5 H. angustifolius L. Erect, slender, scabrous or hispidly hirsute; lvs. sessile, lance-linear, tapering to a long point, 1-veiued, rigid, opposite, the upper often alternate, subdenticulate, often revolute; hds. pedunculate, few t scales lance-linear, the long point spreading; pales linear, 3-toothed. - Sandy or rocky places, N. J., Ky., and S. States, common. St. 2 to 3f high, subsimple. Lvs. 2 to 6' by 3 to 6", broadest at the abrupt base. Rays 12 to 18, expanding about 2 . Disk flowers brown at the summit. Aug. - Oct
6 H. rigidus Desf. St. rigid, simple or with few branches, scabrous or smooth-ish, nearly naked above; lvs. lanceolate, tapering to each end, petiolate, mostly opposite, tripli-veined, serrulate or entire, rigid, scabrous both sides; hds. few; scales in many rows ovate, acute, regularly imbricate, shorter than the disk; pales obtusish. - Prairies, etc, Wis. (Lapham), to Mo., La., etc. Plant 2 to 4f high. Lvs. 3 to 6' by 1/2 to 1', very rough with papillous hairs, but less so than H. divari-catus. Rays 12 to 20, expanding 2 to 3", light yellow. (H. scaberrimus Ell.)
7 H. atrorubens L. St. with few long, naked peduncles above, hirsute below: lvs. ovate, or oval, obtusish, abruptly contracted into winged petioles, subserrate. rough or hispid, 3-veined; scales obovate or oblong, obtuse, 3-veined, about equaling the disk; pales obtusish. - Dry soils, Va. to Fla. and Ark. St. 2 to 4f high. Lvs. mostly near the base, large. Hds. small, few, with 12 to 15 rays, 9 to 10" long. Aug. - Oct.
8 H. giganteus L. St. rough, hairy lvs., alternate (the lowest opposite), lanceolate, acuminate, serrate, scabrous, obscurely 3-veined, tapering at base into short, ciliate, winged petioles; scales lanceolate-linear, ciliate; pappus of 2 short, slightly fringed scales. - Can. to Car. and Ky., in low grounds and thickets. Stem 4 - 8f high, purplish, branching above into a corymbous panicle of large, yellow flowers. Leaves 2 - 5' by 1/2- 1', opposite or alternate in various degrees. Rays 12 - 20. Variable.
"ß. ambiguus. Lvs. nearly all opposite, sessile and rounded at base." - L. I. (T. & G.)
9 H. tomentosus Mx. St. stout, pubescent, branched above; lvs. mostly alternate, acuminate, nearly entire, scabrous above, tomentous or nearly glabrous beneath, lower ones ovate, petiolate, upper long-lanceolate, subsessile; hds. long-pedunculate ; scales lance-linear, long-acuminate, villous, squarrous; chaff 3-toothed, hirsute at summit. - Dry soils, I11. to Ga. Plant 4 to 8f high, with ample lvs. and fls. Lvs. 6 to 12' by 2 to 6', some of them triph-veined. Rays elliptical lanceolate, about 15" long. Aug. - Oct. †
ß. Lvs. oval, mostly opposite. - Ga. (H. spatulatus Ell.;
10 H. grosse-serratus Martens. St. smooth and glaucous; lvs. mostly alternate, lanceolate, or lance-ovate, long-acuminate, sharply serrate, scabrous above, hoary and softly pubescent beneath, abruptly contracted into naked petioles; scales lance-subulate, loosely imbricated, sparingly ciliate, as long as the disk. - Ohio, Ind., I11., to La. Allied to H. giganteus. St. 4 to 6f high. Lvs. 6 to 9' by 1 to 2', broadest near the base, lower ones rather coarsely serrate. Rays 15 to 20, expanding near 3'. Aug., Sept.
11 H. tuberdsus L. Jerusalem Artichoke. Boot bearing oblong tubers; lvs. 3-veined, rough, lower ones opposite, cordate-ovate, upper ovate, acuminate, alternate; petioles ciliate at base. - Ц Native of Brazil. The plant has been cultivated for the sake of its tuberous roots, which are used for pickles. It is naturalized in borders of lields, hedges, etc. Sept.![]()
12 H. laetifldrus Pers. St. rough and branched above; lvs. oval-lanceolate, acuminate, serrate, tripli-veined, very rough on both sides, on short petioles, upper ones often alternate; scales ovate-lanceolate, ciliate, appressed, a little shorter than the disk; chaff entire or 3-toothed; rays 12 to 20. - Barrens, etc., Ind., Ohio (Torr. & Gr.) A rough, but showy plant, 3 to 4f high. Lvs. thick, 5 to 8' by 1 1/2 to 2 1/2'. Rays nearly 2' in length. Disk yellow. Aug. - Oct. †
13 H. occidentals Riddell. St. slender, simple, nearly naked above; lvs. opposite, oval, scabrous, obscurely serrate, contracted at base into long, hairy petioles, upper ones small and few, entire; hds. pedunculate; scales lance-oval, appressed. Sand prairies, W. States. St. 3 to 5f high, scape-like, slender. Lvs. 3 to 5' by 1 to 2', upper ones 1 to 2' long. Hds. few, middle size. Rays 12 to 15, light yellow. Jl. - Sept. †
14 H. mollis Lam. St. villous; lvs. ovate, acuminate, sessile, cordate and clasping, entire or subserrate, tomentous canescent, opposite, upper ones sometimes alternate ; scales lanceolate, villous canescent; pales entire, acute and canescent above. Prairies and barrens, Ohio, Ind., Mo., common. A hoary and villous species, 2 to 4f high, nearly simple. Lvs. 3 to 5' long, 1/2. to 3/4 as wide. Rays 15 to 25, 1/2 to 1' by 1/4'. Jl - Sept. (H. canescens Mx.)
 
Continue to: