ASCLEPIADALEAE. 741 



Flowers 4-6 mm. broad ; corona-hoods 2-3 mm. high. 



Plant nearly or quite glabrous ; leaves lanceolate or oblong-lanceolate. 



6. A. incarnata. 

 Plant pubescent; leaves oblong. 7. A. pulchra. 



* * * Corolla greenish, purplish, yellowish or white; leaves opposite or verticillate. 

 Leaves ovate, oblong, ovate-lanceolate, obovate or orbicular. 

 Plants glabrous throughout, or minutely pubescent above. 

 Leaves sessile, clasping or very short-petioled. 



Peduncles of the solitary or several umbels short. 



Leaves ovate-oblong ; hoods 2-auriculate at the base. 



8. A. Sullivantii. 

 Leaves nearly orbicular ; hoods truncate. 9. A. lati/olia. 



Peduncle of the usually solitary umbel elongated. 



Leaves cordate-clasping, wavy-margined. 10. A. amplexicaulis. 



Leaves sessile, fiat ; horn not exceeding the hood. 



11. A. Me adit. 

 Leaves manifestly petioled. 



Corolla greenish; umbels loose; pedicels drooping. 12. A. exalt ata. 

 Corolla white ; umbels dense. 13. A. variegata. 



Corolla pink ; some of the leaves verticillate in 4's. 14. A. quadrifolia. 

 Plants, at least the lower surfaces of the leaves, canescent or tomentose. 

 Follicles tomentose, covered with soft spinose processes. 



Corona-hoods obtuse, short. 15. A. Syriaca. 



Corona-hoods elongated, lanceolate. 16. A. speciosa. 



Follicles with no spinose processes, glabrous or pubescent. 

 Leaves wavy-margined; corolla-segments 9-1 1 mm. long. 



17. A. arenaria. 

 Leaves fiat; corolla-segments 4-6 mm. long. 18. A. ovalifolia. 



Leaves lanceolate, oblong-lanceolate or linear. 



Leaves opposite, lanceolate or oblong-lanceolate. 



Leaves thick, short-petioled; inflorescence woolly. 19. A. br achy Stephana. 



Leaves thin, slender-petioled ; inflorescence downy. 20. A. peremiis. 



Leaves mostly verticillate in 2's-6's, narrowly linear. 



Hoods entire. 21. A. verticillata. 



Hoods dorsally hastate-sagittate. 22. A. galioides. 



Leaves scattered, densely crowded, filiform-linear. 23. A. pumila. 



1. Asclepias tuberosa L. Butterfly-weed. Pleurisy-root. (I. F. f. 

 2900.) Hirsute- pubescent; stems stout above, very leafy, 3-6 dm. high, the milky 

 sap scanty. Leaves usually all alternate, lanceolate or oblong, sessile or short- 

 petioled, 5-15 cm. long; umbels cymose, many-flowered; peduncles shorter than 

 the leaves; pedicels pubescent; corolla-segments oblong, obtuse, about 6 mm. 

 long, greenish; hoods erect, oblong, bright orange, or rarely yellow, 2-3 times 

 as long as the stamens, slightly longer than the filiform horns; fruiting pedicels 

 decurved; follicles nearly erect, finely pubescent, 10-12 cm. long. In dry fields, 

 Me. and Ont. to Minn., Fla., Tex. and Ariz. June-Sept. 



2. Asclepias decumbens L. Decumbent Butterfly-weed. (I. F. f. 

 2901.) Hirsute-pubescent; stems 6-9 dm. long, the ends ascending or erect. 

 Leaves sessile or short-petioled, oblong or elliptic, obtuse at the apex, narrowed and 

 often inequilateral at the base, 5-8 cm. long, the upper opposite, the lower com- 

 monly alternate, the uppermost very small; umbels racemose along the branches; 

 peduncles stout; pedicels slender, somewhat pubescent; corolla-segments oblong, 

 acuti-h. about 6 mm. long; the hoods erect, oblong, orange, slightly longer than 

 the subulate horn; follicles more slender than in the preceding. In dry fields, Conn, 

 to 111.. Ohio. N. Car. and Fla. June- Aug. 



3. Asclepias lanceolata Walt. F i:\v-flowered Milkweed. (I. F. f. 2902.) 

 Nearly glabrous; stem usually simple, naked above, 6-12 dm. high. Leaves 

 opposite, distant, elongated, acuminate, narrowed at the base, short-petioled, 10-25 

 cm. long, roughish on the margins, the primary nerves widely spreading; umbels 

 few-flowered, solitary or 2-4 at the summit; peduncles about equalling the slender 

 puberulent pedicels ; corolla-segments oblong, 9-1 1 mm. long, deep red ; hoods ob< >vate 

 or oblong, 2-toothed near the base, nearly twice the length of the anthers and longer 

 than the subulate incurved horn; anther-wings notched at the base; fruiting ped- 

 icels decurved; follicles erect, minutely puberulent, fusiform, alx>ut I dm. long. 

 In swamps, N. J. to Fla. and Tex., mostly near the coast. June-Aug. 



