Hymmatherum. COMPOSITE. 35*7 



167. HYMENATHfiRCJM, Cass. ('Yrfv, membrane, dftfo awn, the 

 paleae 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. Fendl. 

 88, & PI. Wright, i. 115; Benth. & Hook. Gen. li. 410. Hymenatherum (excl. 

 § 2), Dysodia § Aciphyllaa, & Gnaphaliopsis, DC. Prodr. Now adding Thy-. 

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

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



§ 1. AciphyllJia, 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 copious large 

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

 bracts: rays oblong. — Dysodia t (Aciphyllcea) acerosa, DO. Prodr. v. 641. Aciphyltcea 

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

 dary, Wright, &c. (Mex.) 



§ 2. Dtsomopsis, Gray, 1. c, excl. spec. Paleae 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, 

 laciniately and spinulosely dentate or almost pinnatifid : 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, PI. ii. 361. — Low 

 prairies, Texas ; first coll. by Drummond. 



§ 3. Euhtjienatherum, 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 turbinate, 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 palea; 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, Wright. 



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

 •(— Most of the palese 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. polyohsetum, 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 : 



