744 FLORA. 



the recurved fruiting pedicels, 7-10 cm. long. In moist soil, Minn, to Br. Col. 

 Kans., Utah and Cal. May-July. 



17. Asclepias arenaria Torr. Sand Milkweed. (I. F. f. 2916.) Densel; 

 tomentose-canescent all over ; stems simple, ascending or erect, stout, 3-6 dm 

 high. Leaves obovate or oval, thick, obtuse or retuse and cuspidate at the apex 

 truncate, subcordate, obtuse, or rarely some of them narrowed at the base, 5-n 

 Cm. long, the angle of the primary nervation broad; umbels densely many-flowered 

 short-peduncled or sessile; corolla greenish white, its segments oval-oblong; hood 

 oblong, truncate at each end, oblique at the apex, longer than the anthers, with ; 

 broad tooth on each side within; horn semi-lunate with an abruptly incurved sub 

 ulate apex; follicles puberulent, 5-10 cm. long, erect on the decurved fruiting pedi 

 eels. On sand-bars and hills, Neb. and Colo, to Mex. and N. Mex. June-Sept. 



18. Asclepias ovalifolia Dec. Oval-leaved Milkwort. (I. F. f. 2917. 

 Finely tomentose all over; stem simple, usually slender, erect, 3-6 dm. high 

 Leaves oval, ovate, oblong or ovate-lanceolate, 5-8 cm. long, short-petioled, th 

 upper surfaces becoming glabrate; umbels solitary or few, many-flowered; pedun 

 cles short; corolla greenish-white or purplish, its segments ovate-oblong, obtu 

 hoods oval-oblong, nearly twice as long as the anthers, bearing a large acute toot] 

 on each of the inner margins'; horn subulate, incurved over the stigma; follicl 

 ascending on the reflexed fruiting pedicels, pubescent. In woods and on prairies 

 111. to S. Dak., Manitoba and the N. W. Terr. June-July. 



19. Asclepias brachystephana Engelm. Short-crowned Milkweee 

 fl. F. f. 2918.) Puberulent when young, soon glabrate; stems clustered, oftei 

 branched, spreading or ascending, 15-25 cm. long. Leaves lanceolate or linear 

 lanceolate, long-acuminate, 5-8 cm. long, or the lowest shorter; umbels several 

 terminal and axillary, few-flowered; peduncles short; pedicels equalling or longe 

 than the peduncles; corolla greenish purple, its segments about 4 mm. long; hood 

 ovate, obtuse, shorter than the anthers, the short erect-incurved horn slightly ex 

 serted; follicles erect on the spreading or decurved fruiting pedicels, downy o 

 hoary, acuminate. 5-9 cm. long. In dry soil, Kans. (according to B. B. Smyth) 

 Wyo. to Tex., Ariz, and Mex. June-Aug. 



20. Asclepias perennis Walt. Thin-leaved Milkweed. (I. F. f. 2919. 

 Puberulent above, glabrous below ; stem slender, erect, sometimes slightly wood- 

 at the base, 3-9 dm. high. Leaves lanceolate, oblong or ovate-lanceolate, acumin 

 ate or acute at both ends, 5-15 cm. long, glabrous or nearly so ; umbels solitary 

 or several and corymbose; peduncles 2.5-5 cm - l° n g; pedicels slender; flowers ver; 

 small, white ; corolla-segments oblong, 2-4 mm. long ; hoods oval, erect, entire 

 about as long as the anthers, shorter than the subulate-filiform incurved horn 

 follicles glabrous, erect on the erect fruiting pedicels; seeds 11-13 mm. long, ver; 

 thin, destitute of coma. On river-shores and in wet places, N. Car. to 111., Mo. 

 Fla. and Tex. May- Aug. 



21. Asclepias verticillata L. Whorled Milkweed. (I. F. f. 2920. 

 Roots fascicled; stem slender, pubescent in lines at least above, very leafy, 3-8 dm 

 high. Leaves narrowly linear, sessile, verticillate in 3's~7's or some of ther 

 alternate, glabrous or nearly so, their margins narrowly revolute ; umbels usuall; 

 numerous, small; peduncles slender ; pedicels filiform; corolla greenish white, it 

 segments oblong, 3-4 mm. long; hoods white, oblong, entire, about equalling th 

 anthers, much shorter than the subulate incurved horn ; follicles erect on th 

 erect fruiting pedicels, narrowly spindle-shaped, glabrous, 5-7 cm. long. Dry field 

 and hills. Me. and Out. to the N. W. Terr.. Fla., Mex. and N. Mex. July-Sept. 



22. Asclepias galioides H. 15. K. Bedstraw Milkweed. (I. F. f. 2920a 

 Glabrous, except the minutely pubescent stems and pedicels. Stems erect, 3-5 dm 

 high from a horizontal ruotstock ; Leaves erect or spreading, in whorls of i-t 

 narrowly linear. 5-8 cm. long, the margins revolute; peduncles longer than th 

 pedicels and shorter than the leaves; umbels l<»-20 mm. in diameter; flower 

 greenish white; corolla-segments 4 mm. long; hoods as high as the anthers, broad 1; 

 rounded at the summit, dorsally hastate-sagittate, the ventral margins slightly in 

 volute, entire; horn arising from the base of the hood. long-exserted over th 

 anthers; anther-wings minutely notched at the base; follicles erect on erect fruiting 



Is, attenuated, 5-7 cm. long, glabrous or nearly so. Kans. to Colo., Ariz 

 and Mex. May July. 



