ASCLEPIADACEiE. 233 



late, acute or shortly acuminate, petiolate, tomentose beneath ; umbel sub- 

 terminal, many-flowered, somewhat nodding ; leafets of the crown ovate, 

 the margin 2-toothed. A. Cormdi Decaisne. 



Fields and road sides. Can. to Virg. W. to Miss. July, Aug. %—Stem 2—4 

 feet high. Leaves &—S inches long. Uwhels lateral and terminal, 15 — 20-flow- 

 ered. Flowers large, pale purple. Follicles 2 — 5 inches long, covered with soft 

 flexible spines. The leaves are said to be used in preparing the indigo dye in 

 woollen manufactories. The reasons given for changing the old name of this 

 plant do not appear to me to be satisfactory. Common Milkweed. 



•j-f- Follicles S7)ioolh. 

 a. Leaves opposite. 



2. A. phytolaccoides Pursh : stem erect, simple ; leaves broad-lanceolate, 

 acuminate, smooth above, paler and somewhat pubescent beneath ; umbels 

 many-flowered, lateral and terminal, solitary, on long peduncles, nodding ; 

 leafets of the crown truncate, the inflexed margin 2-toothed at the summit ; 

 horn much exserted, subfalcate. A. exaltata and acuminata Muhl. A.nivea 

 Hook. 



Wet rocky grounds. Can. to Car. W. to Miss. Jime, July. %.~-Stem 3—4 

 feet liigh. Leaves large, and resembling those of Phytolacca decandra. Umbels 

 few-flowered, on long peduncles. Flowers large, greenish-purple. A more deli- 

 cate species than the preceding. Poke-leaved Milkweed. 



3. A. incarnata Linn. : stem erect, branched above, more or less pubes- 

 cent ; leaves lanceolate, subsessile, somewhat tomentose ; umbels numerous, 

 erect, mostly in pairs and terminal ; leafets of the crown not toothed ; horn 

 exserted, subulate. A. p^dchra Willd. 



Banks of streams. Can. to Car. W. to Miss. July, Aug. %.—Stevi 2—4 

 feet high, with pubescent lines or hairy tomentose. Umbels numerous, rather 

 small. Flowers bright purple. Swamp Silkweed. 



4. A. purpurascens .hinn. : stem simple, with two pubescent lines ; leaves 

 ovate-elliptic or ovate, mucronate, abruptly attenuated into a short petiole, 

 smoothish above, pubescent and paler beneath ; leafets of the crown ob- 

 long; horn falcate, horizontal, acute. A. amozna Mich. 



Woods. Mass. to Virg. Ohio, and Ken. July, Aug. %—Stem 2—3 feet 

 high, rather slender. Leaves with the midrib broad and purple. Umbels many- 

 flowered, near the summit of the stem. Flowers deep purple. Well defined by 

 the pecuhar curvature of the horn. Purple Silkweed. 



5. A. obtmsifolia Mich. : stem simple, erect, smooth ; leaves closely sessile, 

 somewhat cordate and clasping, oblong, obtuse, undulate on the margin, 

 very smooth, glaucous beneath ; umbel terminal, long peduncled, generally 

 solitary, many-flowered ; leafets of the crown slightly 2-toothed ; horn ex- 

 serted. A. purpurascens Walt. 



Sandy fields. N. Y. to Car. June. %.—Stem 2—3 feet high. Umhels 1—3, 

 terminal, on long peduncles. Flmoers large, pale purple. Wavy Milkweed. 



G. A. variegata Linn.: stem simple, with 2 pubescent lines; leaves 

 ovate or obovate, attenuated at base into a petiole, smooth, at length some- 

 what waved; umbels on short peduncles; the peduncles and pedicels 

 woolly ; leafets of the crown without teeth ; horn broad, with a horizontal 

 point. A. hybrida Mich. 



