4(3). Hoods noticeably dilated above the middle, repand to emarginate at the 

 broad apex; corolla greenish-white or yellow 2. A. oenotheroides. 



4. Hoods not dilated above the middle, rounded and sometimes slightly notched 



at the apex; corolla deep-rose 3. A. purpurascens. 



5(2). In natural position the hoods extending at least a third longer than the 

 anther head (6) 



5. Hoods shorter than to only slightly longer than the anther head (7) 



6(5). Hoods acute to obtuse at apex; leaves ovate to lanceolate 4. A. rubra. 



6. Hoods broadly rounded at apex; leaves linear-lanceolate 5. A. lanceolata. 



1{5). Leaves more or less heterophyllous at the nodes, linear, all of them 4 mm. 

 wide or less 6. A. subverticillata. 



7. Leaves not heterophyllous, mostly lanceolate to linear-lanceolate, typically 



most of them more than 5 mm. wide (8) 



8(7). Hoods obovate, without horns 7. A. longifolia. 



8. Hoods oblong to quadrate, with conspicuous acicular horns that more or less 



arch over the anther head (9) 



9(8). Corolla usually bright-crimson or scarlet, the lobes 5-10 mm. long 



8. A. curassavica. 



9. Corolla white to bright-pink, the lobes 3-5 mm. long (10) 



10(9). Inflorescences usually paired at the upper nodes, solitary below; flowers 

 typically bright-pink 9. A. incarnate. 



10. Inflorescences solitary at the upper nodes; flowers white, the corolla oc- 



casionally tinged with purple on outer surface (11) 



11(10). Follicles erect on erect pedicels; seeds comose; distribution central and 

 west Texas 10. A. texana. 



11. Follicles pendulous; seeds naked; distribution southeast Texas 



11. A. perennis. 



1. Asclepias speciosa Torr. Showy-milkweed. 



Herbaceous perennial; stems usually very stout, simple, 6-10 dm. tall, densely 

 white-tomentose generally; leaves opposite, shortly petiolate, broadly ovate or oval 

 to rather narrowly oblong or ovate-lanceolate, usually very broadly obtuse to 

 rounded at apex, rather rarely acute, very broadly obtuse to rounded and some- 

 times broadly and shallowly cordate at base, 6-20 cm. long, 3-14 cm. broad, 

 firmly membranaceous, very densely white-tomentose beneath, more or less 

 glabrate above; petioles to 15 mm. long; inflorescences lateral and solitary at 

 few to several of the upper nodes, several- to many-flowered, densely white- 

 tomentose throughout; peduncles rather stout, to 1 dm. long; pedicels 2-3 cm. 

 long; flowers very large and showy; calyx lobes lanceolate, 5-6 mm. long, very 

 densely white-tomentose; corolla purplish-rose, the lobes 1-1.5 cm. long; gynos- 

 tegium pale-rose or pinkish-cream, subsessile; column very broadly obconic, 

 about 1 mm. long and 3 mm. broad; hoods very narrowly ovate-lanceolate, 

 gradually attenuate at apex, widely spreading, 1-1.4 cm. long; horn adnate 

 toward the base, falciform-acicular, sharply incurved, very much shorter than 

 the hoods; anther head broadly truncate-conic, about 3 mm. long and 4.5 mm. 

 broad; follicles erect on deflexed pedicels, broadly or rather narrowly fusiform, 

 abruptly or gradually attenuate, 9-12 cm. long, 2-3 cm. broad, densely spiny to 

 smooth, very densely white-tomentose; seed oval, 6-9 mm. long, the white coma 

 3-4 cm. broad. 



Widely tolerant to habitat and becoming weedy in cult, fields, also in wet 

 meadows and wet alkali soils, along roadsides and railways on the High Plains in 



1340 



