208 
** More or less shrubby, with firmer and more simply lobed leaves. 
3. P.incanum HBK. Shrubby, 3 to9dm. high, much branched, canescent with 
fine tomentum: leaves mostly obovate in outline, sinuately-pinnatifid into 3 to 7 
oblong or roundish and obtuse lobes: heads numerous, paniculate-cymose: ligules 
commonly longer than broad: pappus a pair of short-subulate erect or at length 
spreading awns.—Dry hills of extreme western Texas. 
4. P. argentatum Gray. Suffrutescent, 3 dm. high, silvery-canescent with close 
tomentum: branches erect, rather leafless above, bearing comparatively large and 
few heads: leaves lanceolate to spatulate in outline, some entire or incisely 2 or 
3-toothed; the larger incisely pinnatifid into 2 to 7 acute lateral lobes: pappus a pair 
of lanceolate chaffy awns.—Southwestern borders of Texas. 
*** Perennial herb, with larger heads and leaves, the latter undivided and thickish. 
5. P. integrifolium L. Rough-pubescent, 3to 9 dm. high: leaves oblong or ovate, 
crenate-toothed, or the lower (7.5 to 15 em. long) cut-lobed below the middle: heads 
many in a very dense flat corymb.—Dry ground, extending into Texas from the 
Eastern States. 
47. IVA L. (MARSH ELDER. HIGHWATER-SHRUB.) 
Herbaceous or shrubby coarse plants, with thickish leaves (lower 
opposite), small nodding greenish-white discoid heads, the pistillate 
fertile and staminate sterile flowers in the same heads (the former few 
and marginal), nearly separate anthers, few and roundish involucral 
bracts, smallreceptacle with narrow chaff, obovoid or lenticular achenes, 
and no pappus. 
* Heads in panicled spikes, scarcely bracteate: corolla of the 5 fertile flowers a mere rudi- 
ment or none, 
1. I. dealbata Gray. Canescent with floccose wool except the elongated and nar- 
row terminal panicle, 3 to 6 dm. high: leaves mostly alternate, soft-tomentose, from 
obscurely angulate-toothed to laciniately pinnatifid, cuneately or abruptly con- 
tracted at base into a short winged petiole: heads nearly sessile: involucre of 5 
obovate concave somewhat herbaceous bracts.—Valleys of southwestern Texas. 
2, I. ambrosizfolia Gray. Hirsute or villous-hispid, paniculately branched, 3 to 
6 dm. high: leaves almost all alternate, thin, twice or thrice pinnately parted into 
small oblong lobes: heads pedicellate, in looser panicles: involucre of 5 broadly 
ovate herbaceous outer bracts, and as many smaller obovate thin-scarious inner ones. 
(Euphrosyne ambrosiefolia Gray.)—Western borders of Texas. 
* * Heads spicate or racemose in the axils of leaves or leaf-like bracts: fertile flowers with 
evident corolla. 
3. I. ciliata Willd. Annnal, 6 to 18 dm. high, rough and hairy: leaves ovate, 
pointed, coarselytoothed, downy beneath, on slender ciliate petioles: heads in dense 
spikes, with conspicuous ovate-lanceolate rough-ciliate bracts: involucral bracts and 
fertile flowers 3 to 5.—In alluvial ground throughout Texas. 
4. I. frutescens L. Shrubby at base, nearly smooth, 9 to 24dm. high: leaves oval 
or lanceolate, coarsely and sharply toothed, rather fleshy, the upper reduced to linear 
bracts in the axils of which the heads are disposed in leafy panicled racemes: involu- 
eral bracts and fertile flowers 5.—Salt marshes, from the New England coast to Texas. 
5. I. angustifolia Nutt. Slender erect annual, strigulose-scabrous or somewhat 
hirsute, 6 to 12 dm. high: lower leaves lanceolate (some of them sparingly serrate) ; 
those of the branches from linear to filiform, the bracteal ones ascending and sur- 
passing the numerous small 3 to 6-flowered subsessile heads which are rather crowded 
and spicate: involucral bracts united by scarious edges into a cup: fertile flowers 
usually solitary.—Gravelly banks or beds of streams throughout eustern and central 
Texas. 
