766 



ASCLEPIADACEAE 



Asclepias 



5o 



Map 1644 



Acerates vindtflora (Raf) Eaton 



^50 



Map 1645 



Asclepias verticillata L. 



50 



Map 1646 



Asclepias tuberosa L 



nal, solitary; peduncles generally less than twice as long as the length of 

 the upper pairs of leaves; pedicels pubescent, usually less than 1.5 cm 



long; corollas greenish white 3. A. Meadii. 



Blades large, the median and upper pairs usually much more than 7 cm long, 



oblong or oblong-ovate, usually abruptly rounded near the apex to a rounded 



or short-acute apex; corollas generally purplish. 



Leaves flat, the margins smooth; umbels terminal and solitary or a few 



axillary; peduncles generally shorter than the subtending upper pair 



of leaves; pedicels glabrous, mostly 2-3 cm long; pods glabrous. 



4. A. Sullivantii. 



Leaves generally with a ruffled margin; umbels terminal and solitary or a 

 few axillary; peduncles generally several times longer than the upper pair 



of leaves; pedicels pubescent, mostly 2-5 cm long; pods puberulent 



5. A. amplexicaulis. 



Leaves more or less petioled, generally narrowed at the base, sometimes rounded 

 or truncate at the base but never cordate. 

 Reflexed petals 3-5 mm long. 



Flowers rose purple (very rarely greenish white) ; plants of low ground. 

 6. A. incarnata. 



Flowers white or pinkish. 



Plants mostly with 3-5 pairs or whorls of leaves, usually 1 or 2 pairs in 



whorls of 3 or 4 leaves 7. A. quadrifolia. 



Plants with more than 6 pairs of leaves, none of them in whorls; plants of 



very low ground 8. A. perennis. 



Reflexed petals more than 5 mm long. 

 Flowers white or tinged with pink. 



Umbels dense; pedicels straight, generally less than 15 mm long; leaves 



with a short tip at the strongly rounded or blunt apex. .9. A. variegata. 



Umbels loose; pedicels more or less drooping, more than 15 mm long; leaves 



mostly long-acuminate at the apex 10. A. phytolaccoides. 



Flowers deep or light purple or lavender. 



Hoods usually exceeding the stigmas about 1.5 mm, with a tooth on each 



side about the middle 11. A. syriaca. 



Hoods usually exceeding the stigmas about 2-3 mm, without a tooth on each 

 side about the middle 12. A. purpiirascens. 



1. Asclepias verticillata L. Horsetail Milkweed. Map 1645. Infre- 

 quent in dry, sandy soil or in moist, prairie habitats in the lake area, 



