GENUS I. 



MILKWEED FAMILY. 



Leaves mostly verticillate in 3's-6's, narrowly linear. 



Hoods entire. 



Hoods dorsally hastate-sagittate. 

 Leaves scattered, densely crowded, filiform-linear. 



i. Asclepias tuberosa L. Butterfly-weed 

 or -flower. Pleurisy-root. Fig. 3383. 



Asclepias tuberosa L. Sp. PI. 217. 1753. 



Hirsute-pubescent ; stems stout, simple, or 

 branched near the summit, ascending or erect, 

 very leafy, i-2 high, the milky sap scanty. 

 Leaves alternate, lanceolate or oblong, acute or 

 sometimes obtuse at the apex, narrowed, rounded 

 or cordate at the base, sessile or short-petioled, 

 2'-6' long, 2"-i2" wide ; umbels cymose, terminal, 

 many-flowered ; peduncles shorter than the leaves ; 

 pedicels \'-\ long; corolla-segments about 3" 

 long, greenish orange ; corona-column about \" 

 long; hoods erect, oblong, bright orange, or yel- 

 low, 2-3 times as long as the stamens, longer than 

 the filiform horns; fruiting pedicels decurved; 

 follicles nearly erect, finely pubescent, 4'-$' long. 



In dry fields, Maine and Ontario to Minnesota, 

 Florida, Texas, Chihuahua and Arizona. Consists of 

 numerous races, differing in shape and size of the 

 leaves and color of the flowers. June-Sept. Wind- 

 or orange-root. Canada-, flux-, tuber- or white-root. 

 Orange swallow-wort. Yellow milkweed. Indian-posy. 



22. A. verticillata. 



23. A.galioides. 



24. A. pumila. 



2. Asclepias decumbens L. Decumbent 

 Butterfly-weed. Fig. 3384. 



Asclepias decumbens L. Sp. PI. 216. 1753. 



Hirsute-pubescent ; stems decumbent, 2-3 

 long, the ends ascending or erect. Leaves sessile 

 or short-petioled, oblong or elliptic, obtuse at the 

 apex, narrowed and often inequilateral at the 

 base, I '-3' long, \'-2\' wide, the upper opposite, 

 the lower commonly alternate, the uppermost 

 very small; umbels several or numerous, many- 

 flowered, racemose along the branches, one 

 usually in each of the upper axils; peduncles 

 stout, short; pedicels slender, pubescent, about 

 i' long; corolla-segments oblong, acutish, dark 

 orange, about 3" long; column about \" high, 

 the hoods erect, oblong, orange, longer than the 

 subulate horn ; follicles slender. 



In dry fields, Illinois and Ohio to North Carolina 

 and Florida. Creeping milkweed. June-Aug. 



3. Asclepias lanceolata Walt. Few-flowered 

 Milkweed. Fig. 3385. 



Asclepias lanceolata Walt. Fl. Car. 105. 1788. 

 A. paiipercula Michx. Fl. Bor. Am. i : 118. 1803. 



Glabrous ; stem slender, usually simple, naked 

 above, 2-4 high. Leaves opposite, distant, linear 

 or narrowly lanceolate, elongated, acuminate, nar- 

 rowed at the base, short-petioled, 4'-io' long, 2"-?" 

 wide, roughish on the margins, the primary nerves 

 widely spreading; umbels few-flowered, solitary or 

 2-4 at the summit; peduncles about equalling the 

 slender puberulent pedicels ; corolla-segments oblong, 

 4"-5" long, deep red; column thick, about i" high; 

 hoods obovate or oblong, obtuse, orange, 2-toothed 

 near the base, nearly twice the length of the anthers 

 and longer than the subulate incurved horn ; fruit- 

 ing pedicels decurved ; follicles erect, minutely 

 puberulent, fusiform, about 4' long. 



In swamps, southern New Jersey to Florida and 

 Texas, mostly near the coast. June-Aug. 



