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 Torn SAND MILKWEED. (I. F. f. 2916.) Densely 

 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, 5-10 

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

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

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

 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- 

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



1 8. 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, the 

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

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

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

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

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

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



19. Asclepias brachy Stephana Engelm. SHORT-CROWNED MILKWEED. 

 (1. F. f. 2918.) Puberulent when young, soon glabrate; stems clustered, often 

 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 longer 

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

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

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

 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 woody 

 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 gl pedicels slender; flowers very 

 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 - l n g verv 

 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 them 

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

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

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

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

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

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



22. Asclepias galioides H. B. K. BEDSTRAW MILKWEED. (I. F. f. 292oa.) 

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

 high from a horizontal rootstock ; leaves erect or spreading, in whorls of 2-6, 

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

 pedicels and shorter than the leaves; umbels 19-26 mm. in diameter; flowers 

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

 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 the 

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

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

 and Mex. May-July. 



