ASCLEPIADACE^. (mILKWEED FAMILY.) 341 



of the peduncles (2-3° high), very leafv ; leaves oblong-lanceolate, acute or 

 pointed, obtuse or obscurely heart-shaped at base; flowers rose-purjde ; hoods 

 scarcely equalling the slender ueedle-poiuted horn. — Swamps, common. — 

 Var. PULCHRA, Ters. ; leaves broader and shorter-petioled, more or less hairy- 

 pubescent, as well as the stem. Milky juice scanty. — With the smooth form. 

 * * * Flowers greenish, i/e!/owish^ ic/iite, or merelij purplish-tinged ; leaves oppo- 

 site or ichorled, or the upper rareli/ scattered. 



-*-- Follicles echinate with soft spinous processes, densely tomentose {smooth, and 

 onltj minuteljf echinate at the apex in n. S),l((rge (3-5' lonr/), ovate and acu- 

 niinate, erect on deflexed pedicels; leaves large and broad, short-petioled ; 

 umbels termincd and lateral. 



6. A. speciosa, Torr. Finely canescent-tomeutose or glabrate,Me mani/- 

 flowered umbel and calyx densely tomentose; leaves subcordate-oval to oblong; 

 corolla-lobes purplish, ovate-oblong, 4 - 5" long ; hoods 5 - 6" long, with a short 

 inflexed horn, tJie truncate summit abruptly produced into a ver// long lanceolate- 

 ligulate appendage. — Along streams, ]Minn. to Ark., and westward. 



7. A. Cornuti, Decaisne. (Common Milkweed or Silkweed.) Stem 

 tall and stout, finely soft-pubescent; leaves oval-ol)long (4-8' long), pale, mi- 

 nutely downy beneath, as well us the peduncles, etc. ; corolla-lobes dull purple 

 to white, 3-4" long; hoods rather longer than the anthers, ovate, obtuse, with 

 a tooth each side of the short stout claw-like horn. — Kich ground, everywhere. 



8. A. Sullivan tii, Engelm. Very smooth throughout, tall ; leaves ovate- 

 oblong with a somewhat heart-shaped base, nearly sessile ; hoods obovate, en- 

 tire, obtusely 2-eared at the base outside ; flowers larger (9" long) and more 

 purple than in the last ; anther-wings 2-toothed at base ; pod nearly glabrous, 

 obscurely spiny chiefly on the beak. — Low grounds, Ohio to Kan. and Minn. 



-f H- Follicles wholly unarmed, either glabrous or tomentulose-pubescent, 



•*-*■ Erect or ascending on the deflexed or decurved fruiting pedicels. 



«= Umbel solitary, on a naked terminal peduncle ; leaves sessile, broad, trans- 

 versely veined, ivavy ; glabrous and pale or glaucous. 



9. A. obtusifolia, Michx. Stem 2-3° high ; leaves oblong irith a heart- 

 shaped clasping base, very obtuse or retuse (2^ - 5' long) ; peduncle 3-12' long ; 

 corolla pale greenish purple ; hoods truncate, somewhat toothed at the sum- 

 mit, shorter than the slender awl-pointed horn. — Sandy woods and fields, not 

 rare, especially southward. A second umbel at the base of the peduncle occa- 

 sionally occurs. 



10. A. Meadil, Torr. Stem slender (1 -2° high) ; leaves ovate or oblong- 

 ovate, obtuse or acutish (1-|-2|' long) , peduncle only twice the length of the 

 upper leaves, pedicels rather short , corolla greenish-white, hoods rounded- 

 truncate at summit, and with a sharp tooth at each margin, somewhat exceed- 

 ing the stouter horn. — Dry ground, 111. and Iowa. June. 



= = Umbels mostly more than one; peduncle not overtopping the leaves. 



a. Leaves large, orbicular to oblong-lanceolate ; hoods broad, little if at all exceed 



ing the anthers . glabrous or some minute pubescence on young parts. 



11. A. Jamesii, Torr. Stem stout (1° high or more): leaves about 5 

 pairs, approximate, remarkably thick, rounded or broadly ov(d, often emarginate. 



