WOOTON AND STANDLEY FLOEA OF NEW MEXICO. 643 



Tribe VI. HELENIEAE. 



Plant tissues, especially the leaves and involucres, with oil glands. 



Rays wanting; plants tall, usually about a meter high. 83. Porophyllum (p. 714). 

 Rays present; plants mostly less than 30 cm. high. 

 • Pappus wholly of capillary bristles. 



Stems woody almost throughout 84. Chrysactinia (p. 714). 



Stems herbaceous; annuals 85. Pectis (p. 714). 



Pappus at least in part of paleae. 

 Bracts of the involucre distinct. 



Perennials; leaves alternate; flowers flesh-colored . 



86. Nicolletia (p. 715). 



Annuals; leaves opposite; flowers yellow 85. Pectis (p. 714). 



Bracts more or less united. 



Bracts united only at the base 87. Boebera (p. 715). 



Bracts united for half their length or more. 



Involucres cylindric; achenes compressed, not striate; annual. 



88. Tagetes (p. 716). 

 Involucres campanulate; achenes terete, striate; annuals or 

 perennials. 

 Low shrub; leaves all entire; heads sessile or nearly so. 



89. Actphyllaea (p. 716). 

 Herbs; leaves mostly pinnatifid; heads slender-peduneled. 



90. Thymophylla (p. 716). 

 Plant tissues without oil-glands. 



Rays persistent; plants more or less woolly. 



Pappus present; rays 3 to 4; heads small, corymbose. 



91. Psilostrophe (p. 718). 

 Pappus none; rays 5 to many ; heads large, solitary at the ends of the branches. 



92. Baileya (p. 718). 

 Rays not persistent; plants with various pubescence. 

 Achenes flat. 



Pappus of about 20 bristles; plants scapose 93. Laphamia (p. 719). 



Pappus a low crown or of 1 or 2 awns; plants not scapose. 



Pappus a lacerate-ciliate crown with sometimes a pair of awns; tall 

 plant 50 cm. high or more with triangular-hastate lea^ 



91. Pbricomb (p. 719). 

 Pappus of 2 awns; low plants seldom more than 10 cm. high, with 



pinnately parted leaves 95. Perityle (p. 719). 



Achenes angled or terete, aever flat. 

 Receptacle chaffy. 



Stems woody; leaves fleshy; pappus of 20 to 25 bristles. 



96. CLAPPIA (p. 719). 



Stems herbaceous; leaves not fleshy; pappus of 5 to lOscarious pales. 



97. (JAIII.AKMA (p. 719). 



Receptacle naked. 



Bracts of the involucre pale or colored, at hast (ho margins and lips 

 Bcarious. 



Involucres 3 to 9-flowered 98. Schkuhria (p. . 



Involucres L2 to many-flowered. 

 Rays wanting !>!). Eymknopappi 



