§ 1. _Annuals; leaves mostly alternate, petiolate; receptacle flat; disk brownish._ 1. H. ánnuus, L. (COMMON SUNFLOWER.) Tall, rough; leaves triple-ribbed, ovate or the lower cordate, serrate; involucral scales broadly ovate to oblong, long-pointed, ciliate; disk usually 1´ broad or more.--Minn. to Tex., and westward; long cultivated, and occasionally found in waste grounds. 2. H. petiolàris, Nutt. More slender, 1--3° high; leaves oblong- or ovate-lanceolate, smaller (1--3´ long), mostly entire; scales lanceolate or oblong-lanceolate, seldom ciliate; disk ½´ broad or more.--Minn. to Tex., and westward. § 2. _Perennials; receptacle convex or at length low-conical; lower leaves usually opposite._ [*] _Involucral scales loose, becoming squarrose, narrowly lanceolate, pointed (½´ long); disk usually purple or brownish; leaves linear, 1-nerved._ 3. H. orgyàlis, DC. Stem glabrous, tall, very leafy; leaves mostly alternate, linear to filiform and entire, or the lowest lanceolate and serrulate; scales filiform-attenuate.--Dry plains, Mo. to Neb., south and westward. 4. H. angustifòlius, L. Stem slender (2--6° high), usually scabrous; leaves long and linear, sessile, entire, with revolute margins; heads loosely corymbed, long-peduncled; scales acute or pointed.--Low pine barrens, N. J. to Ky., and southward. [*][*] _Involucral scales closer, more imbricated, short, unequal and not foliaceous; leaves lanceolate to ovate, mostly opposite and 3-nerved._ [+] _Disk dark._ 5. H. atròrubens, L. _Rough-hairy; stem slender_ (2--4° high), smooth and naked and forking above; _leaves thinnish, ovate or oval to oblong-lanceolate_, or the lowest heart-shaped (3--6´ long), serrate, abruptly contracted into a margined petiole; heads small, corymbed; scales ovate, obtuse, ciliolate, appressed; rays 10--16; pappus of 2 fringed scales.--Dry soil, Va. to Ark., and southward. 6. H. rígidus, Desf. _Stem stout_ (2--6° high or more), simple or sparingly branched, rough; _leaves very thick and rigid, rough both sides, oblong-lanceolate_, usually pointed at both ends, nearly sessile, entire or serrate, the lowest oval; heads nearly solitary, pretty large; scales ovate or oblong, obtuse, or mostly acute, ciliate, appressed; rays 20--25, pappus of 2 large and often several small scales.--Dry prairies, Mich. to Ill., and westward. [+][+] _Disk yellow._ 7. H. lætiflòrus, Pers. Closely resembling the last; leaves rather thinner; heads single or corymbed; scales rather fewer (in 2 or 3 rows), narrower and acute or mostly acuminate.--Dry open places, Ohio to Wisc. and Minn., and southward.--Rays showy, 1--2´ long.