ASCLEPIADACE^E. (MILKWEED FAMILY.;) 241 



base, entire at summit, involute-concave; the falcate or subulate horn free at 

 or below the middle of the horn, and incurved or inflexed over the stigmatic 

 disk. 



8. A. Ovalifolia, Decaisne. Tomentulose-pubescent i stem rather slender : 

 leaves thinnish, from ovate or oval to ovate-lanceolate, mostly acute, rounded 

 at base, distinctly petioled, the midrib and veins slender, the veinlets reticulated : 

 umbels few, loosely 10 to 18-flowered, on peduncles which seldom equal the pedi- 

 cels: corolla greenish-white with purplish outside: hoods oval or broadly oblong 

 in outline, not auriculate at base, the inner margins below the middle extended into 

 a large acute tooth or lobe; the horn broad and rather short: anther-wings rounded 

 and mostly entire. — From the Dakotas to the Saskatchewan and N. Illinois. 



9. A. Hallii, Gray. Puberulent-glabrate : stem stout : leaves thickish, ovate- 

 lanceolate or oblong-lanceolate with rounded base and rather acute apex, 

 short-petioled, the stout midrib and straight veins prominent underneath : umbels 

 few and corymbose, many-flowered, on peduncles somewhat longer than the pedi- 

 cels: corolla greenish-white and purplish: hoods elongated-oblong in outline, 

 entire, hastately 2-gibbous above the narrower base, a little surpassing the sickle- 

 shaped horn : anther-wings unappendaged at base. — Proc. Am. Acad. viii. 69. 

 A. ovalifolia of Fl. Colorado, 114. Colorado. 



++ *+ Follicles erect on erect pedicels : leaves usually verticillate, filiform, 



glabrous. 



10. A. verticillata, L. Stems a foot or two high, slender, very leafy : 

 leaves mostly in whorls of 3 to 6, or some scattered, filiform-linear, with revo- 

 lute margins : umbels numerous, small, many-flowered, on peduncles longer 

 than the pedicels : corolla greenish-white : hoods white, broadly ovate and 

 entire, with somewhat auriculate involute base, barely equalling the anthers, 

 much shorter than their elongated-subulate falcate-incurved horn, — In dry 

 soil, from New Mexico and Colorado to Nebraska, and eastward across the 

 continent. 



Var. pumila, Gray. A span or more high, many -stemmed from a fasci- 

 cled root : leaves much crowded, filiform : peduncles seldom longer than the 

 pedicels. — Proc. Am. Acad. xii. 71. From New Mexico to Nebraska and 

 Kansas. 



§ 2. Anther-wings widening to the broadly rounded base and conspicuously au- 

 riculate-notched just above it : hoods sessile, with a narrow wholly adnate inter- 

 nal crest terminating in a minute horn : pollinia short and thick, arcuate-obovate. 



11. A. Stenophylla, Gray. Puberulent, but foliage glabrous: stems 

 slender, 1 or 2 feet high, simple : leaves long and narrowly linear, with sca- 

 brous and more or less revolute margins and » strong midrib; the upper 

 alternate and the lower opposite: umbels several, 10 to 15 flowered: flowers 

 greenish: hoods whitish, erect, equalling the anthers, conduplicate-concave, 

 the base of each inner margin appendaged by a cuneate erosely truncate lobe, 

 the apex 2-lobed and the narrow internal crest exserted in the sinus in the 

 form of an intermediate tooth : interior crown of 5 very small 2-lobed pro- 

 cesses between the bases of the anthers: follicles long-acuminate, erect on 

 the ascending pedicel. — Proc. Am. Acad. xii. 72. Acerates angustifolia, 

 Decaisne. From Colorado and N. Texas to Nebraska and W. Arkansas. 



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