HELIANTHELLA HELIANTHUS 279 



volucre low hemispheric, the bracts in 1-2 rows, spreading or reflexed; 

 heads solitary on the branches ; leaves alternate, simple, toothed, often 

 decurrent ; annual or perennial. 



1. Rays orange to purplish; stems not winged by 



the leaf-bases 



a. Rays 2-4 cm. long; leaves spatulate to lance- 



oblong, mostly entire H. Hoopesii 



b. Rays about 1 cm. long; leaves linear to linear- 



lanceolate, usually parted into 3-5 linear di- 

 visions H. helenioides 



2. Rays bright yellow, 3-cleft at tip ; stem winged by 



the decurrent bases of the lanceolate to lance- 

 ovate leaves H, autumnale 



HELIANTHELLA Torrey and Gray 1840 HELIANTHELLA 

 (Diminutive of Helianthus, which it resembles) 



PL 40, fig. 7. 



Heads with yellow neutral ray-flowers, disk-flowers yellow or purple, 

 perfect, achenes flattened, somewhat winged, pappus of scales or awns or 

 both; receptacle with chaff, involucre hemispheric, the bracts in 2-3 rows, 

 more or less leaf-like; heads solitary; leaves alternate, simple, mostly en- 

 tire ; perennial. 



1. Disk yellowish 



a. Disk 2-3 cm. wide; rays 2.5-4 cm. long; stems 



2-5 ft. high H. quinquenervis 



b. Disk 1-2 cm. wide; rays 1.5-3 cm. long; stems 



1-2 ft. high H.Pdrryi 



2. Disk dark purple 



a. Heads several ; rays 5-6 mm. long H. microcephala 



b. Heads mostly solitary ; rays 2-3 cm. long H. uniHora 



HELIANTHUS Ljnne 1753 SUNFLOWER 

 (Gr. helios, sun, anthos, flower) 



PI. 39, fig. 7. 



Heads with yellow neutral ray-flowers, disk-flowers yellow, brown or 

 purple, perfect, achenes oblong or obovate, flattened or somewhat 4-angled, 

 pappus of 2 scales or awns falling readily ; receptacle flat, conic, with chaff, 

 involucre hemispheric, the bracts imbricated in several rows ; heads solitary 

 or in corymbs ; leaves opposite or alternate, simple ; annual or perennial. 

 1. Disk brown or purplish 



a. Leaves all, or nearly all, opposite, thick, 



leathery, toothed, lanceolate to lance-oblong H. rigidus 



