leaflike bracts; involucre scarcely graduated, about 3 mm. long, the scarious tips 

 of the phyllaries relatively inconspicuous. G. strictum Gray. 



Moist or wet places, mountain meadows and at edge of ponds in N. M. (Union 

 and Rio Arriba cos.) and Ariz. (Coconino Co.), Aug.-Sept.; Wyo. to N.M. and 

 Ariz. 



4. Gnaphalium palustre Nutt. Lowland cudweed. 



Annual; stems 5-20 cm. tall, many and branching from often decumbent base, 

 erect or ascending; herbage loosely floccose-woolly, the wool long and eventually 

 more or less deciduous; leaves spatulate, acute, 1-3 cm. long, tapering to a sessile 

 or subsessile base, the upper leaves oblong or lanceolate and little reduced; in- 

 florescences scattered; the densely aggregated heads in globose terminal and 

 axillary clusters, the latter at the tips of short or reduced branches, all clusters 

 leafy-bracted, the encircling leaves longer than the heads; phyllaries loosely woolly, 

 linear, the tips whitish, scarious; achenes smooth or scabrous; pappus bristles 

 falling separately, not hairy at base. 



Stream beds, vernal pools, or low moist areas in N. M. (San Juan Co.) and 

 Ariz. (Coconino, Yavapai, Gila, Maricopa, Pinal and Yuma cos.), Apr.-Oct.; 

 Alta. and B.C. to N.M., Ariz., Calif, and Baja Calif. 



18. Pluchea Cass. Marsh-fleabane. Stinkweed 



Aromatic annual or perennial herbs; leaves alternate; blades simple, unlobed, 

 usually crenate or serrate, ovate to linear-lanceolate, glabrous to glandular- 

 pubescent to floccose; petioles present or absent; heads usually crowded in 

 corymbiform terminal aggregations; involucre campanulate to hemispheric; 

 phyllaries, strongly imbricated, herbaceous to chartaceous; receptacle flat, naked; 

 ray flowers absent; disk flowers very numerous, a few central ones perfect but 

 infertile, the much more numerous outer ones pistillate and fertile; corolla rose to 

 rose-purple or creamy-white, tubular, the corolla of the staminate central flowers 

 5-lobed, that of the fertile flowers 3-lobed; achenes less than 1 mm. long, cylindri- 

 cal, dark-brown or reddish-brown, 4- to 6-angled or with prominent ridges, setose 

 to hirtellous or glabrous and with a minute white enlargement basally; pappus a 

 single series of fine barbellate bristles. 



A genus of about 9 species of the Americas. 



1. Leaves broadly elliptical to lanceolate or ovate to ovate-lanceolate, petiolate 

 or sessile, if sessile the bases of the blades narrowed to the midribs, 

 neither auriculate-clasping nor truncate (2) 



1. Leaves oblong to oblong-ovate or oblong-elliptical to oblong-lanceolate, sessile, 



the bases of the blades auriculate-clasping to truncate, not nar- 

 rowed to the midribs (3) 



2(1). Leaves petiolate; phyllaries with resin-globules, only the outermost puberu- 

 lent and ciliate; the aggregation of heads characteristically elongate 

 and paniculiform, not flat-topped, each branch terminating in a 

 convex aggregation 1. P. camphorata. 



2. Leaves sessile or petiolate; phyllaries glandular or not, the outermost and 



median ones copiously puberulent and ciliate, the inner ones 

 sparsely puberulent on their summits; the overall aggregation of 

 heads cymiform, the younger branches elongating and exceeding 

 the more central ones, thus producing a flat-topped or layered 

 inflorescence 2. P. purpurascens. 



3(1). Corollas creamy-white; heads 8-10 mm. high; outer phyllaries obtuse or 

 obtuse-apiculate 3. P. foetida. 



3. Corollas rose-purplish; heads 4-6 mm. high; outer phyllaries acuminate 



4. P. rosea. 



1633 



