THISTLE FAMILY 957 



10, the inner 5, usually 3-awned, the outer 1-awned. H. Thurberi A. Gray. D. 

 cupulata A. Nels. D. Thurberi B. L. Robins. Dry hills: Tex. s Utah Ariz.; 

 Mex. Mr-N. 



114. PECTIS L. LEMON-SCENT. 



Rather low, branching, mostly aromatic or strong-scented, annual or perennial 

 herbs. Leaves opposite, glandular-dotted, mostly entire, usually with several 

 pairs of marginal bristles near the base. Heads usually small, solitary or cymose, 

 radiate. Involucre from cylindric or oblong to campanulate or turbinate; 

 bracts 3-12, free, in a single series, without calyculum, glandular-dotted, rounded- 

 carinate at least below; receptacle naked. Ray-flowers few, pistillate and fer- 

 tile; ligules yellow or tinged with red or purple. Disk-flowers rather few, hermaph- 

 rodite and fertile; corollas yellow. Style hispidulous, the short branches 

 obtuse and without appendages. Achenes linear, terete or somewhat angled, 

 pubescent or glabrate. Pappus various, of few or many squamellae, awns, or 

 bristles, or rarely reduced to a mere crown. 



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

 2 additional awns. 1. P. angustifolia. 



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

 bristles. 2. P. papposa. 



1. P. angustifolia Torr. Glabrous annual, lemon-scented; stem branched, 

 5-20 cm. high; leaves narrowly linear; involucres 4-5 mm. high, 2-3 mm. broad; 

 bracts linear, about 8; ligules oblong, about 3 mm. long. P. papposa sessilis M. 

 E. Jones. "Sand-draws" and sandy hillsides: Tex. Neb. Colo. Ariz.; Mex. 

 Son, Mont. Ap-O. 



2. P. papposa A. Gray. Annual, glabrous; stem branched from the base, 

 5-30 cm. high; leaves narrowly linear, 3-5 cm. long; involucres about 4 mm. high 

 and 3 mm. broad; bracts 7-9, linear; ligules 4-5 mm. long. Sandy places: Calif. 



-s Utah N.M. Son. Au-O. 



115. ACHILLEA (Vaillant) L. YARROW, MILFOIL. 



Perennial caulescent, usually villous, herbs. Leaves alternate, from serrate 

 to tripinnatifid. Heads several, usually radiate. Involucre campanulate to 

 hemispheric; bracts imbricate in 3-4 series, the outer usually much shorter. Re- 

 ceptacle conic or convex, chaffy; paleae membranous. Ray-flowers few, 5-12, 

 pistillate and fertile; ligules short and broad, in most species white or sometimes 

 pink or purple. Disk-flowers 15-75, hermaphrodite and fertile; corollas yellow- 

 ish white or straw-colored. Anthers with ovate obtuse tips. Style-branches in 

 the pistillate flowers oblong, obtuse, in the hermaphrodite ones with truncate, 

 fimbriate tips. Achenes oblong or obovate, obcompressed, callous-margined, 

 glabrous. Pappus wanting. 



Leaves pinnatifid to tripinnatifid. 



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. Palmeri. 

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



3. A. fusca. 

 Involucre 3.54 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. paciflca. 



Involucre 44.5, rarely 5 mm. high, 2.5-4 mm. broad. 



Ultimate leaf-segments linear; rachis merely margined. 



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



7. A. lanulosa. 



