666 ASCLEPIADACEAE (MILKWEED FAMILY) 



12. A. variegata L. Stem 3-9 dm. high ; leaves (4-5 pairs) ovate, oval, or 

 obovate, somewhat wavy, contracted into short petioles, middle ones sometimes 

 whorled ; pedicels (numerous and crowded) and peduncle short, downy ; divi- 

 sions of the corolla ovate, white; hoods orbicular, entire, purplish or reddish, 

 the horn semilunar with a horizontal point. Dry woods, L. I. to Ind., s. to 

 Fla., and w. La. May, June. Remarkable for its compact umbels of nearly 

 white flowers. 



b. Leaves mostly pubescent or puberulent; hoods obtuse, entire, twice or thrice 

 the length of the anthers. 



13. A. ovalifblia Dene. Low, 1.5-6 dm. high, soft-downy especially the 

 lower surface of the ovate or lanceolate-oblong acute short-petioled leaves 

 (3.5-8 cm. long); umbels loosely 10-18-flowered, sessile or peduncled ; pedicels 

 slender ; hoods oblong, yellowish, with a small horn, about the length of the 

 oval greenish-white corolla-lobes (tinged with purple outside). Prairies and 

 oak openings, 111. and Wise, to S. Dak. and Man. June, July. 



w- -M- Follicles and pedicels erect ; leaves often whorled ; glabrous or nearly so. 

 = Leaves ovate to broadly lanceolate, thin, rather slender-petioled. 



14. A. quadrifblia Jacq. Stem slender, 3-8 dm. high, mostly leafless below, 

 bearing usually one or two whorls of four in the middle and one or two pairs 

 of ovate or ovate-lanceolate taper-pointed petioled leaves (0.5-1 dm. long); pedi- 

 cels slender; corolla-lobes pale pink, oblong ; hoods white, elliptical-ovate, the 

 incurved horn short and thick. Dry woods and hills, N. H. to Ont. and Minn., 

 s. to N. C. and Ark. May-July. 



15. A. per6nnis Walt. Stems 3-7 dm. high, persistent or somewhat woody 

 at the base; leaves lanceolate or lanceolate-ovate, tapering to both ends, thin, 

 rather slender-petioled ; flowers white, small ; the small hoods of the crown 

 shortv^than the needle-shaped horn; seeds sometimes destitute of a coma! 

 Low grounds, Ind. to Mo., Fla., and Tex. May-Aug. 



= = Leaves narrowly linear to filiform; horn subulate, exserted; column 



conspicuous. 



16. A. verticillata L. Stems slender, simple or sparingly branched, 3-9 dm. 

 high, from a fibrous root, very leafy to the summit ; leaves linear, with revolute 

 margins, 3-6 in a whorl ; umbels small, lateral and terminal ; divisions of the 

 corolla ovate, greenish- white ; hoods roundish-oval, about half the length of the 

 incurved claw-shaped horns. Prairies and open woods, Mass, to Sask., and 

 southw. 



17. A. pumila (Gray) Vail. Similar; low (1-1.5 dm. high) and many- 

 stemmed from a woody caudex ; leaves much crowded, spirally arranged, filiform 

 or filiform-linear. (A. verticillata, var. Gray.) Dry plains, w. la. and Neb. 

 to Col. and N. Mex. 



2. Anther-wings broadly rounded at base and conspicuously auriculate-notrlu <l 

 just above it; hoods with a minute horn exserted from the 2-lobed apex. 



18. A. stenophylla Gray. Puberulent, but foliage glabrous ; stems slender, 

 0.3-1 m. high ; leaves narrowly linear, the upper alternate, lower opposite ; 

 umbels several, short-peduncled, 10-15-flowered ; corolla-lobes oblong, greenish ; 

 hoods whitish, equaling the anthers, conduplicate-concave ; follicles erect on 

 ascending pedicels. (Acerates angustifolia Dene.) Dry prairies, Neb. to Mo., 

 southw. and westw. June-Aug. 



3. ACERATES Ell. GREEN MILKWEED 



Nearly like Asclepias ; but the hoods destitute of crest or horn (whence the 

 name, from a- privative, and x^pas, a horn). Flowers greenish, in compact 

 many-flowered umbels. Leaves opposite or irregularly alternate, short-petioled 

 or sessile. Pollen-masses slender-stalked. Follicles not tuberculate. 



