201 
*** Pappus of the fertile flowers not flaccid, little if at all elongated in Sruit, not very 
copious: achenes only 5-nerved (occasionally 4-nerved ). 
+ Involucral bracts from oblong to linear, rather firm and with green center or costa, 
6. B. Bigelovii Gray. Stems copiously and loosely branched, 3 to6 dm. high: leaves 
somewhat rigid, from linear to oblong and the broader ones sometimes petioled, irregu- 
larly serrate, commonly obtuse: heads over 4 mm. high, numerous in a cymose pani- 
cle: bristles of the male pappus thickened and barbellate at the tip.—In the Che- 
nate Mountains. 
7. B. Havardi Gray. Stems copiously branched, slender: leaves hardly at all 
rigid; lower linear-oblanceolate and tapering into a slender petiole, laciniate- 
pinnatifid into several irregular slender-subulate lobes; those of the branchlets 
narrowly linear, 2 or 3-toothed or entire: heads loosely paniculate, only the male 
known, these barely 4 mm. high: involucral bracts ublong: pappus-bristles rigid, 
clavellate.—Guadalupe Mountains. 
+ + Involucral bracts broader, thin-chartaceous, destitute of green center or distinct costa, 
8. B. glutinosa Pers. Stems herbaceous above but woody towards the base, 9 to 
30 dm. high: leaves elongated-lanceolate, serrate with few or scattered teeth on each 
side: heads mostly 6 mm. long (or the male smaller), numerous and corymbosely 
cymose at the summit of comparatively simple stems or branches: involucre yellow- 
ish.—Along streams and in moist ground, western Texas. 
34. PLUCHEA Cass. (MARSH-FLEABANE.) 
Herbs or shrubs, with alternate pinnately veined leaves, cymosely 
clustered heads of purplish flowers, flowers all tubular, the central per- 
fect but sterile (with 5-cleft corolla), all the others pistillate and fertile 
and with a thread-shaped truncate corolla, imbricated involucre, flat 
naked receptacle, tailed anthers, grooved achenes, and a simple pap- 
pus of capillary bristles. 
* Pappus of sterile lowers of more rigid bristles thickened at tip: involucre coriaceous : 
very leafy sericeous-canescent shrubs, 
1. P. borealis Gray. (CACHIMILLA. ARROW-WoOOD.) Much branched shrub, 
willow-like, with cymulose-glomerate heads, silvery with the very close and fine 
appressed pubescence: leaves entire, linear-lanceolate, sessile, acute at both ends: 
outer involucral bracts ovate, obtuse, tomentose.—Sandy banks of streams, along 
the Upper Rio Grande. 
** Pappus of both kinds of flowers fine and similar, none of the bristles at all thickened 
at tip: involucral bracts thin: heavy-scented herbs, somewhat pubescent and gland- 
ular. 
2. P. bifrons DC. Perennial, 6 to 9 dm. high: leaves closely sessile or half: clasp- 
ing, oblong to lanceolate, sharply denticulate, veiny, 5 to 7.5em. long: heads clus- 
tered in a corymb: involucral bracts lanceolate.—Wet soil, extending in the low coast 
country from New Jersey to southern Texas. 
3. P. camphorata DC. Annual, pale, 6 to 15 dm. high: leaves scarcely petioled, 
oblong-ovate or lanceolate, thickish, obscurely veiny, serrate: corymb flat: involu- 
cral bracts ovate to lanceolate (P. fetida DC.).—In salt marshes or moist saline soil 
throughout Texas. 
35. PTEROCAULON Ell. (BLAcK-Roor.) 
Perennial herbs, tomentose-canescent except the upper face of the 
sessile pinnately veined leaves (these decurrent on the whole stem, 
forming wings), small sessile whitish heads spicate at the summit of the 
