Hymenatherum. COMPOSITE. 357 



167. HYMENATHERUM, Cass. ('Y/xryv, membrane, dflifc, awn, the 

 paleo3 of the pappus awned.) Low herbs or suffruticulose plants (chiefly of the 

 Mexican borders), of various habit, mostly pleasant-scented ; with alternate or 

 opposite leaves, and small or barely middle-sized usually radiate heads of yellow 

 flowers. Cass. Bull. Philom. 1817, 1818, & Diet. xxii. 313; Gray, PI. Pencil. 

 88, & PL Wright, i. 115; Benth. & Hook. Gen. n. 410. Hymenatherum (excl. 

 2), Dysodia Aciphyllcea, & Gnaphaliopsis, DC. Prodr. Now adding Tliy- 

 mophylla, Lag. (slightly earlier published name, but obscure), & Lowellia, Gray, 

 with inuticous pappus. Vide Proc. Am. Acad. xix. 40. 



1. ACIPHYLLJ:A, Gray. "Paleae of the simple pappus numerous (18 to 20), 

 above resolved into about 5 or the alternate ones into 3 capillary bristles, like 

 those of Dysodia (to which it makes transition) : heads sessile or nearly so at the 

 end of the woody branchlets : leaves entire, opposite. -- PL Wright, i. 115. 



H. acerosum, GRAY, 1. c. Shrubby, a span to a foot high from a thick base-, rigid, exceed- 

 ingly branched : branches barely puberulent : leaves filiform-acerose, usually with shorter 

 ones fascicled in most of the axils : heads 3 or 4 lines high : involucre with copioiis large 

 oil-glands, subtended by uppermost pair of leaves or by a few shorter subulate foliaceous 

 bracts: rays oblong. D/jsodial (Aciphijllaa) acerosa, DC. Prodr. v. 641. Aciphyllita 

 acerosa, Gray, PI. Fendl. 91. W. borders of Texas to Arizona toward the Mexican boun- 

 dary, Wright, &c. (Mex.) 



2. DYSODIOPSIS, Gray, 1. c., excl. spec. Paleje of the simple pappus only 

 10, rigid, not longer than the thickish akene, much shorter than disk-corolla, 

 some entire with a single awn, others with 3 aristate-subulate tips : heads loosely 

 foliose-calyculate : leaves alternate. 



H. tagetoides, GRAY, 1. c. A rigid annual, and becoming perennial, glabrous, a foot or so 

 high, fastigiately branched at summit: leaves narrowly linear, 2 or 3 inches long, rigid, 

 laciuiatcly and spiuulosely dentate or almost piunatifid : heads indistinctly peduncled, less 

 than half-inch high : involucre rigid ; its bracts obviously imbricated, but connate almost to 

 the tip: rays oblong, conspicuous. Dysodia tagetoides, Torr. Gray, Fl. ii. 361. Low 

 prairies, Texas ; first coll. bj Drummond. 



3. EUHYMENATHERUM, Gray, 1. c. Paleae of the pappus 10 to 20, all or 

 the inner ones 1-3-aristate, and the awns about equalling or surpassing the disk- 

 corolla : heads naked at base, or with some small and scanty subulate accessory 

 bracts. (See also 4.) 



* Rays inconspicuous and few, with ligule not surpassing the disk or the double and dimorphous 



pappus; this of 10 rigid palese in each series, inner with stout awns. 



H. Neo-Mexicanum, GRAY. A slender erect annual, a foot or less high, glabrous, fas- 

 tigiately branched above : leaves mostly pinnately parted into a few linear-filiform entire 

 divisions ; lower opposite, upper alternate : heads short-peduncled : involucre turbiuate, 3 or 

 4 lines high, of 5 to 7 oblong connate bracts, subtended by 2 to 4 filiform-subulate bractlets: 

 akenes appressed-villous at the attenuate base, shorter than the inner pappus, the oblong- 

 lanceolate palete of which are cleft into 3 scabrous rigid awns, the middle one longer ; those 

 of the short outer pappus oblong-spatulate, retuse. Proc. Am. Acad. xix. 40. Adenophyllum 

 Wrightii, Gray, PI. Wright, ii. 92. Hillsides, New Mexico, Wriijht. 



# * Rays exserted and conspicuous, oblong: awns of the pappus capillary or slender-setiform. 

 -1- Most of the palere of the nearly homomorphous pappus 3-awned, lateral awns shorter: glabrous 

 leafy -stemmed herbs, either annuals or slender-rooted subperennials : upper leaves all alternate. 



H. polychaetum, GRAY. Low, diffusely much branched from an annual root, leafy to 

 near the numerous short-peduncled heads: leaves not rigid, pinnately parted into several 

 short-filiform obtuse and pointless divisions: involucre barely 3 lines high, 10-16-toothed : 



