322 PITTONIA. 
in the arachnoid-tomentose upper face of the leaves, by its 
more numerous and narrow involucral bracts, the tips of all 
inner ones being sharply, almost setaceously, pointed. 
Often associated, in the District of Columbia, with the 
woodland species, A. decipiens, yet as frequently seen in open 
places along with A. arnoglossa ; about a week later in flow- 
ering than the former, and as much in advance of A. arno- 
glossa in this particular. From A. arnoglossa var. ambigens 
it is not, at a glance, to be distinguished in the herbarium ; 
but in view of the narrow setaceous-pointed inner bracts of 
A. fallax it is easily separated from all others. Much of the 
northeastern plant which I referred to A. decipiens as first 
and too vaguely circumscribed, seems to be A. arnoglossa 
var. ambigens; and a more general investigation of this 
plant seems likely to result in its elevation to the rank of a 
species. 
A. OCCIDENTALIS. Large as A. arnoglossa and A. fallax, 
the stolons as leafy and the habit very similar, but the 
3-ribbed leaves distinctly smaller and narrower, always with 
blade tapering rather gradually to the indistinct petiole; 
pubescence of both faces of the leaf of less flocculent or arach- 
noid character and more truly tomentose, yet tardily decid- 
uous from the upper face of all the foliage: cymose panicle 
of large female heads more open than in either; bracts of 
their involucre few and elongated, forming only 2 or 3 series, - 
by their white tips appearing as in only 2 series, the outer 
of these obovate-oblong, obtuse and serrulate, the inner 
somewhat narrowly lanceolate and abruptly acuminate: 
male plant half as large, all its heads distinctly pedicelied 
and forming a corymb; tips of the hardly biserial bracts 
obovate, obtuse or truncate: pappus-bristles, with rather 
narrow and notably serrate dilatation. 
Common in grassy openings among oak woods along the — 
rivers of the Illinois prairie region, and apparently ‘westward 
to Kansas; perhaps northward to Michigan; though the 
