COMPOSITAE 207 



7. A. Mexicans Willd. Resembles the last : stem taller and more 

 slender, nearly glabrous : upper leaves linear, entire, the lower pinnatifid 

 with linear-oblong segments: involucre nearly glabrous : heads usually 

 not nodding, IV^ long — On barrens and prairies throughout the southern 

 part. July-October. Possibly a form of the last. 



42. ERECHTITES Raf. 

 Alternate-leaved, vile-smelling herbs. Heads corymbose. Marginal 

 flowers pistillate. Pappus of copious fine soft hairs. 



1. E. hieracifolia (L. ) Raf. Fireweed. Annual, usually somewhat 

 hairy, l°-6° high : leaves lanceolate, clasping, sessile or short-petioled, 

 sinuate-dentate : heads 3'^ wide. — Rather common in woods. August- 

 October. 



43. MESADENIA Raf. Indian Plantain. 



Leaves alternate, petioled. Flowers corymbose. Heads bracted, 5- 

 angled. Marginal flowers perfect. Receptacle flat with a pointed pro- 

 jection in the center. Pappus of numerous soft bristles. 



Leaves triaugular-reniform. 1. if. atripHcifoUa. 



Leaves ovate-lanceolate. 2. 31. tuberosa. 



1. M. atriplicifolia (L. ) Raf. Stems 3°-6° high, terete: leaves thin, 

 angulately lobed, glaucous beneath, palmately veined. — Rather common 

 in open woods. — July-September. 



2. M. tuberosa (Nutt. ) Britton. Stems 2°-5° high, angled : leaves 

 thick, entire, strongly parallel-nerved, chiefly basal. — Frequent on 

 prairies, save in the northwestern part. June-July. 



44. SENECIO L. 



Alternate-leaved herbs with corymbose heads of flowers. Receptacle 

 flat. Rays fertile. 



Basal leaves lyrate pinnatifid. 1. S. lohatus. 

 Basal leaves merely crenate. 



Basal leaves cordate at base. 2. S. aureus. 



Basal leaves tapering at base. 3. S. BaJsamitae. 



1. S. lobatus Pers. Butter weed. Annual, l°-3° high, glabrous : 

 leaves all pinnatifid : rays 6-12 : achenes hispidulous. — Locally common 

 in low woods along the Missouri River. May-June. 



2. S. aureus L. Squaw Weed. Perennial, 1°-1^° high, nearly 

 glabrous : basal leaves ovate-cordate : stem leaves pinnatifid : rays 8-12 : 

 achenes glabrous. — Low grounds along the Blue and Little Blue Rivers, 

 but uncommon. May-June. 



3. S. Balsamitae Muhl. Squaw Weed. Resembles the last, but 

 woolly at base : lower leaves oblong-oval : achenes hispidulous. —Prairies 

 near Lee's Summit. Uncommon. April-May. 



45. ARCTIUM L. 



Biennial, alternate-leaved, herbs. Heads corymbose-paniculate. Invo- 

 lucre globular, its scales tipped with hooked bristles. Pappus of short 

 rough bristles. Flowers red or white. 



