228 COMPOSITACEAE (COMPOSITE FAMILY) 



A. Annual; disk flowers brownish or dark purp',e. 

 B. Leaves ovate-lanceolate or v.ider; rays more than 8; chaff of the receptacle 3- 

 toothed or -Cleft, not awnlike at tip; disk often over 12 mm. wide. 

 C. Disk about 1.5 cm. wide; leaves oblong to ovate-lanceolate, 2.5-8 cm. long. E. 



H. petiolaris (prairie sunflower) 

 CC. Disk 2.5 cm. or more wide; at least the lower leaves ovate or cordate, 5-17 cm. 

 long. E. — Often cultivated for beauty or seed. 



H. annuus (common sunflower) 



BB. Leaves lanceolate to linear-lanceolate; rays 5-8; chaff of the receptacle not 



3-toothed, narrowed into awnlike tooth; disk 12 mm. or less wide. U. H. exilis 



AA. Perennial; disk flowers yellow. 



D. Stems 1.2 m. or less high or long, often not erect; plant scabrous, without hairs; 



leaves entire or serrulate. 



E. Stems 3-12 dm. high or long; leaves acute or acuminate, entire or serrulate. E. 



H. nuttallii 

 EE. Stems 1-3 dm. high or long; leaves obtuse, entire. E. H. cusickii 



DD. Stems 1.5-3.5 m. high, erect; plant pubescent or hirsute; leaves coarsely ser- 

 rate or lobed. W. E. — Cultivated for the tubers for stock. 



H. tuberosus (Jerusalem artichoke) 



BIDENS (Beggar-tick) 



Leaves opposite at least below. Heads radiate or rayless; receptacle 

 flat or nearly so. Pappus of 2-6 teeth or awns ; awns retrorsely hispid or 

 barbed. — (L. bi = 2, dens = a tooth; the akenes of some have 2, barbed 

 teeth.) Weeds. Akenes adhere to wool of animals and to clothing. 



A. Leaves usually 5-divided; plant terrestrial; pappus of 7 awns; akene and awns 

 retrorsely barbed to base; annual. E. B. vulgata (s-leaved beggar-tick) 



AA. Leaves serrate to laciniate, or submerged and divided into many capillary seg- 

 ments; pappus of 3-6 awns. 

 B. Annual, terrestrial; stem erect; leaves 7-15 cm. long; rays none or not over 

 16 mm. long; akenes not barbed; pappus awns retrorsely barbed above only. 

 W. E. B. cemua (nodding beggar-tick) 



BB. Perennial, aquatic; stem slender and not usually erect; leaves i-S cm. long; 

 rays 20-25 mm. long; akenes retrorsely barbed at margins; pappus awns retrorsely 

 barbed to base. W. E. 1 B. beckli (water beggar-tick) 



HELENEAE (Sneezeweed Tribe). — Herbs. Heads radiate or appar- 

 ently rayless ; involucre bracts not scarious ; receptacle naked except 

 in Gaillardia. Disk flowers fertile, 4-5-toothed, tubular. Anthers not 

 tailed at base. Style branches of perfect flowers truncate or appendaged, 

 not flat. Pappus none or chaffy or awns or bristles but the bristles not 

 capillary. 



A. Leaves opposite, except sometimes the upper. 

 B. Leaves entire. 

 C. Plants of salt marshes. 

 D. Pappus none, involucre bracts not united. W. — (Honor of I. H. Jaume St. 

 Hilare, a French botanist.) Jaumea carnosa 



DD. Pappus of 5-10 chaffy scales; involucre bracts united to form a 5-15-toothed 

 cup. U. — (Honor of Lasthenia, a pupil of Plato.) Lasthenia glaberrima 



CC. Plants of dry soil, not of salt marshes. 



