162 UNITED STATES AND MEXICAN BOUNDARY. 



Sarcostemma heterophyllum ; var.? umLellis S-B-floris^ pedicellis pedunciilo siib^qualitus; 

 floribus majoribus; corolla) laciniis oblongis obtusis. Gravelly hills, Eock Creek^ and near 

 Camp Bache, also at the moutli of the Great Canon of the Rio Grande^ June — July. (No, 1679^ 



Wright,) Perhaps distinct from S. heterophyllum: we have seen no intermediate forms. The 

 leaves are usually longer and wider; the flowers are of a dull purple color^ and the segments of 

 the corolla are more strongly ciliate, Gynostegium distinctly stipitate. Follicles 4 inches long, 

 a?ute at the base, and tapering to a long point. 



AscLEPiAS Sellivantii, Engelm. in Gray's Manual^ ed. 2, p. 352, Hill-sides, Muerte and Eock 

 Creek ; also at the Copper Mines, July — August ; Bigeloio. The pods are sometimes almost 

 entirely free from warts or spines. Leaves often very obtuse, or even emarginate.- 



AscLEPiAS Jamesii (n. sp.) : glaberrima, subglauca ; foliis orbiculato-obovatis subcoriaceis 

 retusis vel emarginatis basi cordatis brevissime petiolatis ; umbellis multifloris brevi-peduncu- 

 hitis ; gynostegio constricto ; cucullis dilatatis truncatis ; processu arcuato falciformi acutissimo 

 exserto ; folliculis ovatis l^vibus. A, obtusifolia var,? latifolia, Torr, in Ann. Lye. 2, p. 117, 

 Plains near the Limpio Mountains, July; Bigelow. Tascate, Sonora, July; Parry. (No. 1682, 



Wright.) Stem stout, 1-2 feet high. Leaves 3-4 inches long, and 2^-3-^- wide, somewhat 

 coriaceous, transversely and reticulately veined, mostly retuse or emarginate, with a small 

 abrupt point ; the lower ones almost orbicular ; petiole 1-3 lines long. Umbels several, in the 

 axils of the upper leaves. Peduncles 2-4 lines long. Flowers much resembling those of A. 

 ^SuUivantii. Corolla greenish ; segments broadly ovate. Hoods of the crown purplish, very 

 broad, obliquely truncated, the horn with the acute poiut exserted and projected partly over 

 the stigma, tae upper margin undulacoly 2-3-toothed. Horny margins of the anthers angularly 

 dilated at the base. This species was first discovered by Dr. James, on Long's Expedition to 

 the Eocky Mountains, and was doubtfully regarded as a variety of A. obtusa in my account of 



the plants collected by that botanist. It was afterwards found by Lieut. Abert, as well as by 

 Fendler, in New Mexico, 



AscLEPiAS eeosa (n. sp,): puberula delude glabrata: caule erecto simplici; foliis oblongo-ovatis 

 subcoriaceis acuminatis sessilihus margine eroso-denticulatis ; umbellis multifloris ; pendunculis 

 folio duplo brevioribus ; cucullis obovatis obtusis longioribus; gynostegio constricto, processu 

 suhulato arcuato longe liorizontaliter exserto ; folliculis ovatis, acuminatis la3vibus. — Valley 

 of the Gila river, near Metate, May — June ; Schoft^ Thurher. Stem apparently 2-3 feet high, 

 stout. Lower leaves 5-7 inches long, and 2| broad^ with a long acute point, very rough, on the 

 margin, with irregular conspicuous cartilaginous serratures. Umbels 5 to 7, about half as long 

 as the leaves; pedicels H inch long, pubescent. Flowers as large as in A. Cornufci. Corolla 

 greenish white ; segments at length reflexed. Hoods of the crown obliquely truncate at the 

 summit, the subulate horn exserted horizontally. Pods (immature) about 2 inches long, and 

 nearly an inch in diameter at the middle. — Apparently allied to A. glaucescens, H. B, & K., 

 but that sxjccies has obtuse leaves, much shorter pedicels, and a subsessile gynostegium, which 

 is about the length of the hoods. 



AscLEPiAS aeenaria (u. sp.) I incano-pubesceus, deinde glabrescens ; caule simplici; foliis 

 oppositis ohovatis vel inferioribus ovatis breviter petiolatis, superioribus emarginatis vel retusis ; 



+ 



pedunculis brevibus multifloris, cucullis dilatatis obtusissimis utrinque unidentatis gynostegio 

 subsessili longioribus^ processu subulato apice subrecurvo ; folliculis oblongis attenuatis 

 J/Bvibus. — ^Sandy hanks ; Journado del Muerte, and on the upper Eio Grande, in New Mexico, 

 June — July. Plant 12-18 inches high, (apparently sometimes assurgent or prostrate.) Leaves 



