230 ASCLEPIADACEAE. 



long: corolla -lobes 6-7 mm. long: horn arising above the hood-auricles: follicles 

 mostly over 10 cm. long. — Occasional, in dry soil. 



2. A. tuberosa L. Stems mostly erect or ascending, 3-6 dm. tall, hirsute: 

 leaf- blades lanceolate-oblong to linear-lanceolate, 3-9 cm. long: corolla-lobes 

 5-6 mm. long: horn arising opposite the hood-auricles: follicles mostly less 

 than 10 cm. long. — N. S. Common, in fields and on roadsides. — Sandstones 

 and shales, schists. — • Butterfly-weed. Pleurisy-root. 



3. A. amplexicaulis J. E. Smith. Stems 3-10 dm. tall, glabrous: leaf -blades 

 horizontal, oblong or elliptic, 6-12 cm. long: corolla-lobes greenish or greenish- 

 purple, 7-9.5 mm. long: hoods about 4 mm. long, exceeding the androecium, 

 shallowly lobed; horn subulate, much exserted: anther-wings twice as long as 

 wide : follicles 10-16 cm. long. — S. Not very common, on roadsides. — 

 Schists. 



4. A. rubra L. Stems 3-12 dm. tall, glabrous: leaf -blades ovate, ovate- 

 lanceolate, or oblong-lanceolate, 7-20 cm. long: corolla-lobes purple-red, or 

 rarely purplish-green, 7-8 mm. long: hoods lanceolate, about 6 mm. long, 

 narrowed to the apex; horn nearly as long as the hood: follicles 9-11 cm. long. 

 — S. Eare, in swamps. — Schists. 



5. A. purpurascens L. Stems 3-12 dm. tall, becoming glabrous: leaf -blades 

 mainly oblong-ovate, 9-20 cm. long: corolla-lobes purple, 8-10 mm. long: hoods 

 4.5-5.5 mm. long, fully twice as long as the androecium, oblong-ovate at the 

 entire apex ; horn much shorter than the hood : anther- wings nearly as wide 

 as long : follicles 10-12 cm. long. — Common, on roadsides and in thickets. — 

 Purple-milkweed. 



6. A. syriaca L. Stems 5-15 dm. tall, becoming glabrous: leaf -blades hori- 

 zontal, oblong or oblong-ovate, 9-15 cm. long: corolla-lobes greenish-purple, 

 6-8 mm. long: hoods 3-4 mm. long, about equalling the androecium, broadly 

 rounded; horn subulate, about as long as the hood: anther-wings much longer 

 than wide : follicles 7-9 cm. long. — Common, in fields and fence-rows. — 

 Common-milkweed. 



7. A. exaltata (L.) Muhl. Stems 9-15 dm. tall, sometimes pubescent in lines 

 above: leaf-blades mainly elliptic to elliptic-lanceolate, 1-2.5 cm. long: corolla- 

 lobes flesh-colored or bluish, 7-8 mm. long: hoods 3.5-4 mm. long, about equal- 

 ling the androecium, erose-truncate ; horn with a much exserted subulate in- 

 curved tip: anther-wings much longer than wide: follicles 12-16 cm. long. — 

 Not common, in thickets and on roadsides. — Poke-milkweed. 



8. A. variegata L. Stems 3-9 dm. tall, sometimes pubescent above: leaf- 

 blades typically oval, varying to ovate or obovate, 6-14 cm. long: corolla-lobes 

 white, 6-8 mm. long: hoods about 3 mm. long, rounded, much exceeding the 

 androecium; horn very broad, with a horizontal tip: anther-wings nearly as 

 wide as long: follicles 10-13 cm. long. — N. S. Common, in woods. — Quarts- 

 ite, schists. 



9. A. incamata L. Stems 6-11 dm. tall, glabrous or puberulent: leaf -blades 

 mainly oblong-lanceolate, 4-17 cm. long, glabrous or nearly so: corolla-lobes 

 pink or rarely white, 4-6 mm. long: hoods oblong, 2.5-3 mm. long, somewhat 

 exceeding the androecivmi ; horn slender, much longer than the hood : follicles 

 7—9 cm. long. — Common, in low meadows and SAvamps and on roadsides. — 

 Swamp-milkweed. 



10. A. pulchra Ehrh. Stems 5-15 dm. tall, closely pubescent: leaf -blades 

 broadly lanceolate to oblong, 6-12 cm. long, pubescent: corolla-lobes rose- 

 purple or rarely white, 5-6 mm. long: hoods oblong, about 2.5 mm. long, 

 slightly exceeding the androecium; horn slender, much longer than the hood: 

 follicles 5-7 cm. long. — N. S. Common, in low meadows and swamps. — 

 Sandstones and shales, schists. 



