A COMPOSITE 335 



54. Centromadia Achenea of the ray-flowers very oblique the small ter- 

 minal areola from the summit of the inner angle or face, on a narrow 

 beak : receptacle convex or conical, chaffy throughout, the chaff distinct. 



* * * Bay-achenes obcompreased or clavate, completely enclosed 

 involucral bracts which are flattish on the back at base and their 

 thin margins abruptly infolded. 



65. Lagophlla Heads few-flowered : ray achenes about 6, obovate, much 

 obcompressed, smooth : disk-flowers sterile : pappus none. 



56 Layia Heads many-flowered ; rays 8-20, with obovate or somewhat 

 clavate smooth achenes; disk-flowers mostly fertile, their similar or 

 narrower achenes often pubescent: pappus cemposed of bristles or sub- 

 ulate pointed scales. 



57 Achyrachtena Heads many-flowered ; the flowers all fertile ; achenes 

 linear-cuheate or clavate, 10-ribbed, some or all of the ribs tuberevlrte- 

 Bcabrous ; those of the disk with a pappus of blunt, silvery-scarious 

 scales in 2 series. 



Subtribe i Ivex Heads undrogynous, bearing Jew pistillate floicers 

 at the margin; the more numerous staminate ones all or most of them 

 subtended by slender chaffy bracts. Anther tips, short and obtuse, 

 rarely pointed. Involucre open. Achenes usually large for the size 

 of the head, free. 



85 IVA L Gen. n. 1059. 



Herbs or shrubs with entire or dentate or dissected leaves, at 

 least the lowest ones opposite, and small spicately or racemosely 

 or paniculately disposed or scattered and commonly nodding heads 

 of inconspicuous flowers. Fertile and sterile flowers in the same 

 heads: the fotmer 1-5, marginal, with a small tubular corolla ; the 

 latter 7-20 (rarely only 2 or 3), with tubular-campanulate or fun- 

 nelform 5-toothed corolla. Bracts of the campanulate or hemi- 

 spherical involucre 3-5, in a single series and more or lesst united 

 into a cup. Receptacle chaffy with linear or spatulate scales sub- 

 tending the sterile flowers. Anthers nearly distinct. Style in 

 the fertile floweas deeply 2-cleft: of the sterile ones undivided. 

 Achenes obovate, thick, often granulate, without a disk at the 

 apex. Pappus wanting. 



1, axillaris Pursh Fl. 743. Herbaceous from somewhat woody creep- 

 ing rootstocks; the stems or branches nearly simple, ascending, 10-20 

 inches high : leaves obovate or oblong to nearly, linear, obtuse, entire, ses- 

 sile, rarely over an inch long, even the uppermost usually much surpassing 

 the mostly solitary heads in their axiles : bracts of the hemispherical 

 involucre connate into a 4-5-lobed or sometimes parted and sometimes 

 merely crenate cup: bracts of the receptacle reduced to fllifol-m chaff. In 

 saline or sandy places, Brit. Columbia to California, New Mex. and the 

 Saskatchewan. 



I. xanthifolia Nutt. Gen ii, 185 "Tall and ciiarse (3-6 feet high), pu- 

 bescent, at least when young: leaves mainly opposite, long-petioled, broad- 

 ly ovate, ample coarsely or incisely serrate, acuminate, 3ribbed at base, 

 pubescently scabrous aboVe and when young canescent beneath : heads 

 nearly sessile, crowded in narrow spiciform clusters which are aggregated 

 in axillary and terminal panicles : involucre depressed-bemisqheric, biser- 

 ial, the outer of 5 broadly ovate herbaceous bracts; inner of as many mem- 



