216 COMPOSITE. (COMPOSITE FAMILY.") 



thickened, and bearded at the tip, partly embracing the flattened and margined 

 achenia. Pappus none, or 2 teeth. Perennial herbs, with alternate pinnate 

 leaves ; the grooved stems or branches naked above, and terminated by single 

 showy heads. Rays yellow or party-colored, large and drooping ; the disk gray- 

 ish. (Name from Xenit, a scale, and ira^vs, thick, referring to the thickened tips 

 of the chaff.) 



1. 1. pinnata, Torr. & Gr. Hoary with minute appressed hairs, slen- 

 der (4 high), brandling; leaflets 3-7, lanceolate, acute; disk oblong, much 

 shorter than the large and drooping light-yellow rays (which are 2' long). 

 Dry soil, from Chatauque County, New York (SartweLl), to Wisconsin and 

 southward. July. The receptacle exhales an anisate odor when bruised. 

 Achenia slightly margined on the inner edge, obscurely 2-toothed at the top. 



39. HELIANTHUS, L. SUNFLOWER. 



Heads many-flowered, radiate ; the rays several or many, neutral. Involucre 

 Imbricated. Receptacle flattish or convex ; the persistent chaff embracing the 

 4-sided and laterally compressed achenia, which are neither winged nor mar- 

 gined. Pappus very deciduous, of 2 thin chaffy-awned scales on the principal 

 angles of the achenium, and often 2 or more little intermediate scales. Coarse 

 and stout herbs (often exuding a resin), with solitary or corymbed heads, and 

 yellow rays : flowering towards autumn. (Name from rjXios, the sun, and avOos, 

 a floiver.) All our wild species are perennial. 



* Disk convex, dark purple : leaves opposite, or the upper alternate. 

 - Scales of the involucre tapering into narrow and spreading herbaceous tips. 



1. H. angllStifoIillS, L. Stem slender (2 -6 high); leaves long and 

 linear, sessile, entire, with revolute margins, 1 -nerved, pale beneath; heads 

 (small) loosely corymbed, long-peduncled. Low pine barrens, New Jersey to 

 Kentucky and southward. 



- - Scales of the involucre regularly imbricated and appresst-d, ovate or broadly 

 lanceolate, obtuse, ciliate, destitute of herbaceous tips. (Leaves nearly all opposite.) 



2. H. atrdmbens, L. Rough-hairy; stem slender (2 -5 high), smooth, 

 and naked and forking above ; leaves thin, ovate or oval, or the lowest heart-shaped 

 (3' -6' long), serrate, abruptly contracted into a margined petiole; heads small, 

 corymbed; rays 10-16; pappus of 2 fringed scales. Dry soil, Virginia, Illi- 

 nois, and southward. 



3. H. rigid us, Desf. Stem stout (l-3 high), simple or sparingly 

 branched, rough ; leaves very thick and rigid, rough both sides, oblong-lanceolate, 

 usually pointed at both ends, nearly sessile, slightly serrate, the lowest oval ; 

 heads nearly solitary, pretty large; rays 20-25; pappus of 2 large and often 

 several small scales. Diy prairies, Michigan to Illinois, and westward. 



# * Disk convex, yellow : scales of the involucre regularly imbricated and appressed, 

 with somewJiat spreading and acute (but not foliaceous) tips : leaves chiejly opposite. 



4. H. IsetiflorilS, Pers. Stout and rough (3 -4 high), branching above; 

 leaves oval-lanceolate, very rough both sides, narrowed into short petioles, serrate, taper- 

 pointed, the uppermost alternate and nearly entire ; heads single or corymbed, 



