378 ASCLEPIADACEAE 



tan or pink, 5-6 mm. long ; hoods yellow, shorter than the stamens ; horns with the tips barely 

 exserted ; pedicels erect in fruit ; follicles tomentulose when young, narrowly lanceoloid, taper- 

 ing at both ends, 8-11 cm. long, about 12 mm. thick. 



Dry rocky canyons and washes, Lower Sonoran Zone; southeastern Mojave Desert and the Colorado Desert, 

 California, to Lower California and Arizona. Type locality: Los Angeles Bay, Lower California. Dec. -May. 



9. Asclepias speciosa Torr. Greek or Showy Milkweed. Fig. 3845. 



Asclepias speciosa Torr. Ann. Lye. N.Y. 2: 218. 1828. 

 Asclepias Douglasii Hook. Fl. Bor. Amer. 2: 53. pi. 142. 1834. 



Stem simple, stout 4-12 dm. high, herbage more or less hoary-tomentose throughout, or 

 glabrate especially below, pale green. Leaves opposite, short-petioled, ovate-lanceolate to broadly 

 ovate, acute or obtuse at apex, cordate or rounded at base, 7-15 cm. long, 3-10 cm. broad; 

 peduncles 2-8 cm. long; umbels usually several, all pedunculate, many-flowered; pedicels and 

 calyx densely hoary-tomentose; corolla-lobes rose-purple, 8-10 mm. long, lanceolate, obtuse, 

 tomentose on the back ; hoods contracted above the broad involute base into a flat lanceolate 

 tip, two to three times as long as the stamens, pale pink; horn about 3 mm. long, inflexed over 

 the stamen-column ; follicles narrowly ovoid, 6-10 cm. long, densely white-lanate, with scatter- 

 ing soft prickle-like processes. 



Stream banks, moist meadows, open fields or slopes. Upper Sonoran and Transition Zones; British Co- 

 lumbia to California, east to Minnesota and Oklahoma. In the Pacific States mainly east of the Cascade 

 Mountains, in Washington, also Oregon, but extending into Josephine and Jackson Counties; in California 

 it is in the North Coast Ranges to Solano County, the Sacramento Valley, and both sides of the Sierra Nevada 

 to Fresno and Inyo Counties. Type locality: Canadian River. May-Aug. 



10. Asclepias nyctaginifolia A. Gray. Mojave Milkweed. Fig. 3846. 



Asclepias nyctaginifolia A. Gray, Proc. Amer. Acad. 12: 69. 1876. 

 Podostemma nyctaginifolium Greene, Pittonia 3: 237. 1897, 



Stems several from the crown of a rather slender rootstock, decumbent or ascending, 10-20 

 cm. long, herbage light green, puberulent with short rather stiffish slightly recurved hairs. 

 Leaves ovate to ovate-lanceolate, 5-10 cm. long, acute at apex, obtuse at base or somewhat 

 decurrent on the 1.5-3 cm. long petioles, green and puberulent on both sides; umbels subsessile; 

 pedicels short-pubescent ; corolla greenish, the lobes oblong-lanceolate, 10-12 mm. long, thin- 

 nish ; hoods 8-10 mm. long, their sides closely appressed ; horn wing-like, attached well above 

 the middle and produced into a slender slightly exserted straight or somewhat curved point; 

 follicles narrowly ovoid, attenuate at apex, 5-6 cm. long, puberulent. 



Dry slopes of desert ranges, Sonoran Zones; Providence and New York Mountains, eastern Mojave 

 Desert, San Bernardino County, California, east to southeastern Arizona. Type locality: Rock Springs, 

 Providence Mountains, California. May-Sept. 



11. Asclepias subulata Decne. Rush Milkweed or Ajamete. Fig. 3847. 



Asclepias subulata Decne. in A. DC. Prod. 8: 571. 1844. 



Stems several, erect, usually woody below, often branched above, stiff and rush-like, 1-2 m. 

 high. Leaves few, or often wanting, almost filiform, 2-6 cm. long; umbels few to many, ra- 

 cemosely arranged on the branches, mostly 3-10-flowered; peduncles 1-2.5 cm. long; pedicels 

 rather stiff and ascending in anthesis, tomentose, the subtending bracts caducous ; calyx-lobes 

 tomentose ; corolla-lobes 7-8 mm. long, greenish white, sometimes tinged with purple at the tip ; 

 hoods 6-7 mm. long, twice the length of the stamens ; horn attached near the middle of the hood 

 and included or the tip slightly exserted. 



Canyons and washes, Lower Sonoran Zone; eastern Mojave Desert and Colorado Desert, California, to 

 Nevada, Arizona, Lower California, Sonora, and Sinaloa. Type locality: "Nov. Hispania?" Probably in one 

 of the above Mexican states. April-Dec. 



6. ASCLEPI0D6RA a. Gray, Proc Amer. Acad. 12: 66. 1876. 



Herbs, similar to Asclepias in general habit, with alternate or opposite leaves, and 

 rather showy flowers in terminal, solitary or corymbose umbels. Sepals 5, lanceolate. 

 Corolla rotate, deeply divided, the segments spreading. Hoods of the crown oblong, 

 curved upward, crested within, the stamen-column bearing lobes or appendages alternate 

 with the wings of the anthers and simulating an inner crown. Anthers scarious-tipped, 

 the wings horny, narrowed below and sometimes angled above. Pollen-masses pendulous 

 on the caudicle and longer than it. Follicles with or without soft spinose processes, ovoid, 

 acuminate; fruiting pedicels erect or ascending on the decurved or twice-curved fruit- 

 ing pedicels. Seeds conspicuously comose. [Name Greek, meaning gift of Aesculapius.] 



A North American genus of about 6 species, inhabiting the southern United States and Mexico. Type 

 species, Asclepias viridis Walt. 



1. Asclepiodora decumbens (Nutt.) A. Gray. Antelope Horns. Fig. 3848. 



Ananthrix decumbens Nutt. Trans. Amer. Phil. Soc. II. 5: 202. 1837. 

 Asclepias brevicornu Scheele, Linnaea 21: 756. 1848. 

 Asclepiodora decumbens A. Gray, Proc. Amer. Acad. 12: 66. 1876. 

 Asclepias capricornu Woodson, Ann. Mo. Bot. Card. 32: 370. 1945. 



Stems herbaceous, decumbent or ascending, minutely hispidulous with recurved hairs, 25-60 

 cm. high. Leaves firm, ascending, lanceolate to linear, acuminate at the apex, narrowed at base 

 to a short petiole, 3-15 cm. long; umbel solitary on a terminal peduncle, many-flowered; pedicels. 



