THISTLE FAMILY 



259 



Plant annual; llgules partly or wholly purple. 2. G. pulchella. 



Lobes of the disk-coroUas short and broad, acute or obtuse. 



Plant hirsute or villous; leaves neither coriaceous nor conspicuously punctate. 

 Pappus-squamellae lanceolate, awn-pointed. 



Disk purple; leaf-segments more or less ascending. 



Leaves, except the earliest ones, pinnatifld with narrow divisions. 



3. G. pinnatiflda. 

 Leaves entire or with broad divisions. 



Perennials with a thick root. 4. Gf. gracilis. 



Annuals or biennials; root not thick. 5. G. Mearnsii. 



Disk pale yellow; leaf-segments divaricate. 6. G. fiava. 



Pappus-squamellae elliptic, muticous, or with a very short awn-tip; disk yellow. 

 Squamellae with a distinct midrib, usually minutely awn-tipped.' 



7. G. Pringlei. 

 Squamellae without midrib and awn-tip. 8. G. arizonica. 



Plant minutely and sparingly puberulent; caudex thick and woody; leaves coriaceous, 

 conspicuously punctate. 

 Plant distinctly caulescent; leaf-blades spatulate to linear. 9. G. spathulata. 



Planiacaulescent, scaoose; basal leaf-blades broadly obovate. 10. G. Parryi. 



1. B. papposa. 



1. T. aurea. 



2. T. Thurberi. 



112. BOEBERA Willd. Fetid Marigold. 



113. THYMOPHYLLA Lag. Tiny Tim. 

 Annuals; pappus-squamellae muticous. 

 Perennials; pappus-squamellae awn-tipped. 



114. PECTIS L. Lemon-scent. 



Flowers subsessile; pappus of a crown of 4 or 5 connate squamellae, sometimes with 1 or 

 2 additional awns. 1. P. angustifoUa. 



Flowers distinctly peduncled; pappus at least of the disk-flowers of 12-18 barbellate 

 bristles. 2. P. papposa. 



115. ACHILLEA (Vaillant) L. Yarrow, Milfoil. 



Leaves pinnatifld to tripinnatifld. 



Bracts with dark brown, almost black margins. 

 Involucre 5-6 mm. high, 4-5 mm. broad. 



Ultimate segments of the leaves long and linear, not thickened at the apex; 



bracts all acute. 1. A. borealis. 



Ultimate segments of the leaves ovate, lanceolate, or oblanceolate, short, often 

 thickened at the apex; bracts except the outermost obtuse. 

 Upper leaves 1-2 cm. broad, with spreading not densely crowded divisions. 



2. A. Palmen. 

 Upper leaves 5-10 mm. broad, with short densely crowded divisions. 



3. A. fusca. 

 Involucre 3.5-4 mm. high, about 3 mm. broad. 4. A. subalpina. 



Bracts with light brown, yellowish, or straw-colored margins. 

 Involucre 5-8 mm. high, 4 mm. broad or more. 



Ultimate divisions of the leaves linear, not thickened, spreading, not crowded ; 



bracts with light brown margins. 5. A. californica. 



Ultimate divisions lanceolate or ovate, usually thickened towards the apex, 

 ascending and crowded; bracts and their margins of the same color, light 

 yellowish or straw-colored. 6. A. pacifica. 



Involucre 4-4.5, rarely 5 mm. high, 2.5-4 mm. broad. 

 Ultimate leaf-segments linear; rachls merely margined. 



Ligules 2.5-4 mm. long; leaf-segments ascending, crowded. 



7. A. lanulosa. 

 Ligules 1.5-2.5 mm. long; leaf-segments more or less spreading, not crowded. 



8. A. occidentalis. 

 Ultimate leaf-segments ovate or lanceolate; racUs distinctly winged. 



9. A. millefolium. 

 Leaves serrate or incised, not pinnatifld. 10. A. muUiflora. 



116. ANTHEMIS L. Corn Chamomile. 



1. A. arvensis. 



117. MARUTA Cass. May Weed, Dog Fennel, Dog Chamomile. 



1. M. Cotula. 



118. CHAMOMILLA (Hall.) Gilib. Chamomile, Pineapple-weed, Green 

 Dog-fennel. l. C. suaveolens. 



119. LEUCANTHEMUM (Tourn.) Mill. Ox-eye Daisy, l. L. Leucanthemum. 



120. TANACETUM (Tourn.) L. Tansy. l. T. vulgare. 



121. SPHAEROMERIA Nutt. 



Plant shrubby, 2-4 dm. high, glabrous; heads several, corymbose. 1. S. ditersifolia. 

 Plant with cespitose caudices, 1.5 dm. or less high, silvery-canescent ; heads solitary or 

 in a small cluster. 



