WOOTON AND STANDLEY—FLORA OF NEW MEXICO. 645 
Bracts of the involucre nearly equal and alike; all dis- 
tinct. 
Leaves dissected ; stems leafy throughout. 
115. RypBERGIA (p. 730). 
Leaves entire; stems naked or with only a few leaves. 
116. TETRANEURIS (p. 730). 
Tribe VII. ANTHEMIDEAE. 
Receptacle chaffy; rays white. 
Achenes flattened; heads small.............-...-+------ 117. AcuILuEa (p. 733). 
Achenes terete; heads large....................220-004- 118, ANTHEMIS (p. 733). 
Receptacle naked; rays white or usually wanting. 
Heads radiate; rays white..............-.----.--119. CHRYSANTHEMUM (p. 734). 
Heads discoid. 
Heads corymbose, bright yellow, showy.......... 120. TANACETUM (p. 734). 
Heads not corymbose, not bright yellow, inconspicuous. 
Plants spiny; achenes cobwebby.......-..- 121. PicrotHAMNUS (p. 734). 
Plants not spiny; achenes not cobwebby....... 122. ARTEMISIA (p. 734). 
Tribe VIII. SENECIONEAE. 
Involucre of 4 to 6 bracts; stems woody throughout.......123. TeTRADYMIA (p. 739). 
Involucre of more than 6 bracts; stems woody at the base or entirely herbaceous, 
Pappus of plumose bristles; leaves mostly wanting or reduced to scales. 
124. Bessa (p. 740). 
Pappus not of plumose bristles; leaves evident. 
Involucral bracts erect-connivent, equal, sometimes with a few short outer 
ones. 
Leaves opposite; pappus a single series of rigid bristles. 
125. Arnica (p. 740). 
_ Leaves alternate; pappus of numerous soft bristles. 
Heads usually radiate; corollas yellow; leaves bipinnatifid to entire. 
126. Senecio (p. 740). 
Heads discoid; corollas white; leaves thrice pinnatifid into narrow 
segments.....-.2..-----0-0 eee eee 130. MESADENIA (p. 749). 
Involucral bracts not erect-connivent, usually unequal and overlapping. 
Leaves opposite, linear-filiform............- 127. HAPLOESTHES (p. 748). 
Leaves alternate, not linear-filiform. 
Heads homogamous; achenes terete..... 128. PsaTHYROTES (p. 748). 
Heads heterogamous; achenes compressed. 
129. BartLetTTia (p. 749). 
Tribe IX. CYNAREAE. 
Annual; achenes attached obliquely............-.-.------ 131. CENTAUREA (p. 749). 
Perennials or biennials; achenes not attached obliquely. 
Leaves prickly; involucral bracts not slender-subulate, 
the tips not hooked................-..-.2-2---02---- 132. Cirsium (p. 749). 
Leaves not prickly; involucral bracts slender-subulate, 
hooked ......--.----- 2-22 e eee eee eee eee ee eee eee eee 133. Arctium (p. 753). 
1. VERNONIA Schreb. IRoNWEED. 
Tall herbaceous perennials with leafy stems and corymbose inflorescence; heads 
many-flowered, campanulate, the bracts closely imbricated in several series; flowers 
purple; achenes ribbed, the pappus in two series, the outer of short scales or bristles, 
the inner long and capillary. 
