a low crown, in others a few irregular awns up to half as long as the disk corollas; 

 achenes terete, glabrous or slightly pubescent, 1-2 mm. long. 



Infrequent along arroyos and about saline swales in Tex. Davis Mts., Ariz. 

 (Pinal, Cochise, Santa Cruz and Pima cos.), Aug.-Oct.; also Son., Chih. and Dgo. 



8. Euthamia Nutt, 



This genus is often considered as a section of Solidago, but its relationship 

 is apparently not that close. The genus, entirely American, is considered to 

 consist of about 6 species. 



1. Euthamia camponim Greene. 



Essentially glabrous often slightly glutinous rhizomatous perennial; stems erect, 

 3-5 dm. tall, freely branching in the upper half with the branches rather stiffly 

 ascending to form a somewhat corymbiform top to the plant, densely leafy; leaves 

 usually ascending, linear, entire, 3-ribbed, 3-8 cm. long; heads essentially sessile, 

 borne in fascicles; involucre 3-5 mm. high, somewhat campanulate, the outer 

 phyllaries acute to obtuse and wider than the inner ones; receptacle about 2 mm. 

 thick; phyllaries in 3 to 5 series, oblong; ray flowers few, pistillate and fertile, 

 the rays yellow and not exceeding the disk corollas; disk flowers perfect, fertile, 

 10 to 15 per head, with 5-toothed yellow corollas, only slightly exceeding the 

 involucre; pappus alike in ray and disk, of a single series of more or less equal 

 whitish capillary bristles. 



In sandy floodplains of creeks and rivers, in Okla. {Waterfall) and in the Tex. 

 Plains Country (Lipscomb, Wheeler and Wichita cos.), Aug.-Sept.; Kan., Okla., 

 Tex. and Colo. 



9. Machaeranthera Nees 



Herbs; leaves alternate, essentially sessile (especially the basal ones), often 

 pinnately or bipinnately lobed but in some species merely toothed or essentially 

 entire; heads about 1-2 cm. in diameter, usually borne more or less solitary at 

 the ends of branches though occasionally the whole plant subcorymbose or rarely 

 the heads nearly sessile in the upper axils; involucre mostly hemispheric; phyllaries 

 usually linear to lanceolate or subulate, basally and laterally stramineous, the 

 midrib in the upper half herbaceous-green (or at least darker than the stramineous 

 base) and expended into a somewhat rhombic patch that in some species occupies 

 essentially the entire tip-region, the tip either erect or in some species spreading 

 or even squarrose and apically acute to very shortly acute or even blunt; receptacle 

 3-10 mm. wide, rough, flat or very slightly convex; ray flowers pistillate, fertile; 

 rays yellowish or white and often tinged with blue, violet and/or red; disk flowers 

 numerous, perfect, fertile; corollas yellowish, with a cylindrical tube that is not 

 distinctly delimited from the greatly ampliate limb (which is composed of a throat 

 and 5 usually short teeth); style appendages various; achenes narrowly turbinate 

 to broadly linear or clavate, rather densely antrorsely pubescent; pappus persistent, 

 in some species absent from the ray flowers but present in the disk flowers, in 

 other species present and alike in both disk and ray, composed of numerous 

 somewhat unequal usually sordid-white slender bristles, the larger ones often 

 slightly dorsiventrally flattened at the base. Haplopappus Sect. Blepharodon DC; 

 Psilactis Gray, Eriocarpum Nutt.; Xylorhiza Greene. 

 An American genus of perhaps 50 or 60 species. 



1. Ray flowers with evident pappus 3. M. phyllocephala. 



1. Ray flowers with pappus none or vestigial (2) 



1609 



