IVA COMPOSIT A 335 
54 Centromadia Achenes of theray-flowers very oblique, the small ter- 
minal areola from the summit of the inner angle or face, on a narrow 
beak : receptacle convex or couical, chaffy throughout, the chaff distinct. 
* * * Ray-achenes obcompressed or clavate, completely enclosed 
in the involucral bracts which are flattish on the back at base and their 
_thin margins abruptly infolded. 
55 Lagophylla Heads few-flowered: ray achenes about 5, 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 composed of bristles or sub- 
ulate pointed scales or none. 
57 Achyrachena Heads many-flowered; the flowers all fertile: achenes 
linear-cuneate or clavate, 10-ribbed, some or all of the ribs tuberculate- 
scabrous; those of the disk with a pappus of blunt, silvery-scarious 
scales in 2 series. 
Subtribe i Ivee Heads androgynous, bearing few pistillate flowers 
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 tne 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 flowersin the same 
heads: the former 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 less united 
into acup. Receptacle chaffy with linear or spatulate scales sub- 
tending the sterile flowers. Anthers nearly distinct. Style in 
the fertile flowers deeply 2-cleft: of the sterile ones undivided. 
Achenes obovate, thick, often granulate without a disk at the 
apex. Pappus wanting. 
I. 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 filiform chaff. In 
saline or sandy places, Brit. Columbia to California New Mex.and the 
Saskatchewan. 
‘I. xanthifolia Nutt. Gen. ii, 185 ‘ Tall and coarse ( 3-5 feet high), pu- 
bescent, at least when young: leaves mainly opposite, long-petioled, broad- 
ly ovate, ample coarsely or incisely serrate, acuminate, 3-ribbed 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-hemispheric, biser- 
ial, the outer of 5 broadly ovate herbaceous bracts; inner of as many mem- 
