942 



ASCLEPIADACEAE 



Leaf-blades typically oval : umbels globose : pedicels 2 cm. long. 

 Leaf-blades mainly elliptic or elliptic-lanceolate, tapering to each 

 end : pedicels drooping, 5 cm. long. 

 b. Leaf-blades ovate-lanceolate to linear, glabrous ; primary veins ascend- 

 ing, never conspicuously transverse, (see also A. exaltata). 

 Leaf-blades ovate-lanceolate or long-lanceolate, long-acuminate : co- 

 rolla purple-red. 

 Leaf-blades lanceolate to oblong-linear, short-petioled : corolla pur- 

 plish : hoods orange, exceeding the anthers. 

 Follicles erect on erect fruiting pedicels : primary veins of the leaf-blades 

 never transversely ascending. 

 Leaf -blades broad, ovate to ovate-lanceolate, oblong-lanceolate or sometimes 

 lanceolate. 

 Some of the leaves whorled in 4's or 6's : flowers rose-pink. 

 Leaves all opposite. 



Corolla and hoods rose-colored or rarely white. 



Plants glabrous throughout or nearly so : leaves oblong-lanceolate, 



in the variety elongated-linear. 

 Plants hirsute-pubescent : leaves broader. 

 Corolla red-purple : hoods bright orange : leaves oblong to oblong-lan- 

 ceolate. 

 Corolla and hoods white, tinged M'ith green or pink : flowers very small. 

 Leaf-blades oblong-lanceolate or lanceolate, tapering at each end, 



glabrous : seed destitute of coma. 

 Leaf-blades oval-oblong, broad at the petioled base. 

 Leaf-blades linear or filiform : flowers very small, white or greenish tinged. 

 Hoods each terminating in a horizontal or erect lobe: horns exserted. 

 Crown slender-stalked, the stalk less than 1 mm. thick : horn exceed- 

 ing the hood. 

 Leaf-blades filiform or linear-filiform. 



Stems typically solitary : leaves numerous, but not crowded. 

 Stems tufted : leaves contiguous or approximate, very numerous 

 and crowded. 

 Leaf-blades linear. 

 Crown short-stalked, the stalk over 1 mm. thick : horn not exceeding 

 the hood. 

 Umbel typically solitary, sessile : leaves many times longer than 



the internodes. 

 Umbels several, peduncled: leaves shorter than the internodes or 

 less than twice their length. 

 Hoods notched or emarginate : horn included. 

 B. Hoods erect, dilated above the anthers into a lobed or erose open or closed 

 lamina : anther-wings entire or notched at the middle or corniculate at the base. 

 Leaf-blades with ascending veins : umbels all lateral. 



Hoods 5 mm. high : horn single, arising from the apex of the hood. 

 Hoods 8 mm. high, very slender at the stalked base : horn with an acute 

 dorsal accessory process. 

 Leaf-blades with transversely spreading veins : horn arising from the base of 

 the hood, exserted over the anthers. 



11. A. variegata. 



12. A. exaltata. 



13. A. rubra. 



14. A. lanceolata. 



15. A. quadrifolia. 



16. A. incarnata. 

 11. A. pulchra. 



18. A. Curassai'ica. 



19. A. 2xyeiuiis. 



20. A. Texana. 



21. A. verticillata. 



22. A. jnimila. 



23. A. Ii7iearis. 



24. A. Michauxii. 



25. A. viridula. 



26. A. cinerea. 



27. A. Emoryi. 



28. A. Lindheimeri. 



29. A. obovata. 



1. Asclepias deciimbens L. Stems decumbent, 3-6 dm. long, hispid or hirsute- 

 pubescent, the ends ascending or erect : leaves various, the lower commonly alternate, the 

 upper opposite and often notably smaller ; blades oblong, obtuse at the apex, mostly nar- 

 rowed and often inequilateral and sometimes hastate at the base, usually revolute on the 

 margins, 3-19 cm. long : umbels several or numerous, many-flowered, racemose along the 

 branches, one usually in each of the upper axils, on peduncles 1-3 cm. long : pedicels 

 slender, somewhat pubescent, 1.5-3 cm. long: corolla lobes narrowly oblong, acutish, dark 

 or pinkish orange color, 7 mm. long : column distinct : hoods erect, linear, oblong, orange- 

 yellow, slightl}' longer than the subulate inflexed horn, the ventral margins entire or barely 

 lobed at the base : follicles 10-14 cm. long, slender-fusiform, hipsid-pubescent : seeds 7 mm. 

 long, glabrous, marked by fine broken diverging ridges : coma long and abundant. 



In dry fields, New York, Ohio and Hlinois to North Carolina and Florida. Occurring also probably 

 elsewhere further north. Summer. Butterfly Weed. Pleurisy-eoot. 



2. Asclepias tuberosa L. Stems solitary or several, hirsute or rough hirsute-pubes- 

 cent, commonly erect or ascending, 3-6 dm. high or more, simple or branched near the sum- 

 mit, very leafy, the milky sap scanty : leaves usually all alternate ; blades lanceolate-oblong, 

 sometimes lanceolate-linear, acute or more rarely obtuse at the apex, 3-9 dm. long, with 

 margins narrowly revolute : umbels cymose at the ends of the stems or branches, or on old 

 plants sometimes racemose, many-flowered: pedicels pubescent, 1-1.5 cm. long: corolla- 

 lobes narrowly oblong, obtuse, 6-8 mm. long, greenish or reddish orange : column distinct : 

 hoods erect, linear-oblong or linear-lanceolate, bright orange-color or rarely yellow, con- 

 siderably exceeding the anthers and slightly longer tlian the filiform exserted incurved 

 horn, the ventral margins entire or barely lobed and overlapping at the base : anther-wings 

 salient at the entire base : follicles 7-10 cm. long, minutely pubescent : seeds 7 mm. long, 

 glabrous, marked with fine diverging broken ridges : coma long and abundant. 



In dry fields, Maine to Ontario, Minnesota, Colorado, Florida, Texas and Arizona. Summer and 

 fall. Butterfly Weed. Pleurisy-iioot. 



