374 ASCLEPIADACEAE 



corolla greenish purple, the lobes oblong, spreading, 3-4 mm. long ; crown corolla-like, 5-lobed, 

 borne on the base of the corolla-tube and nearly as high as the stamen-column to which it is 

 attached by 5 thin vertical plates ; follicles 5-7 cm. long, sparsely muricate. 



Rocky places. Lower Sonoran Zone; Mojave Desert (near Kelso) and in the Colorado Desert (Ironvvood 

 Well, Corn Springs, Cottonwood Springs), California, south to Lower California, and east to western Texas. 

 Type locality: "Sides of hills, canon of the Rio Grande, below Mt. Carmel, October; Parry. Mountain near 

 the Limpia, western Texas; Wright." March-April or in other months, depending upon time of local rain. 



4. SOLANOA Greene, Pittonia 21 67. 1890. 



Herbs with a stout perennial root, and flattened stems. Umbels terminal or on stout 

 peduncles from the upper axils. Calyx 5-parted, the lobes lanceolate. Corolla S-parted, 

 the lobes reflexed in anthesis. Crown of 5 erect hood-like segments, adnate to the fila- 

 ment-column on the inner surface, and slit vertically on the outer surface from apex 

 to base, witliout horn-like appendages at apex. Anthers tipped with a scarious mem- 

 brane at apex. Follicles smooth. [Name in honor of Solano, chief of the Suisunes.] 



A monotypic Californian genus. 



1. Solanoa purpurascens (A. Gray) Greene. Solanoa or Ground Milkw^eed. 



Fig. 3836. 



Gompkocarpus purpurascens A. Gray, Proc. Amer. Acad. 10: 76. 1874. 



Solanoa purpurascens Greene, Pittonia 2: 67. 1890. 



Asclepias Solanoana Woodson, Ann. Mo. Bot. Gard. 28: 207. 1941. 



Stems few from a woody taproot, prostrate, 2-3 dm. long, flattened and flexuous, herbage 

 pdberulent, with minute incurved hairs. Leaves short-petioled, the blades ovate to elliptic-ovate, 

 the lower obtuse to rounded at base, the upper cordate, obtuse at apex, slightly fleshy ; umbels 

 1-3; peduncles 2-3.5 cm. long; pedicels 7-10 mm^ long; calyx scarcely 1 mm. long; corolla- 

 lobes red-purple, 2.5 mm. long; hoods saccate, 1.5 mm. long, brownish yellow, attached from 

 the base to the apex of the filament-column ; anthers 2 mm. long ; follicles about 5 cm. long, 

 usually only one maturing. 



Serpentine outcrops, Upper Sonoran and Arid Transition Zones; North Coast Ranges in Lake and Colusa 

 Counties, California. Type locality : "California, on the bare summit of a mountain in Lake County, not far 

 from the Geysers." Collected by C. B. Towle. Isotype specimens in the Rattan herbarium give the locality 

 "at summit to Geysers, on the road from Calistoga." June. 



5. ASCLEPIAS L. Sp. PI. 214. 1753. 



Perennial herbs, with erect or decumbent stems, and opposite, verticillate or rarely 

 alternate, entire leaves. Flowers in terminal or axillary, usually pedunculate umbels. 

 Calyx 5-parted or 5-divided, the segments usually small, acute, often glandular within. 

 Corolla 5-parted, the segments mostly valvate in the bud, reflexed in anthesis. Crown 

 usually with a column, the lobes 5, concave and hood-like, spreading or erect, each bear- 

 ing within a slender or subulate, included or exserted horn (wanting in cordifolia and 

 calif ornica. Filaments connate into a tube; anthers tipped with an inflexed scarious 

 membrane, winged, the wings broadened below the middle ; pollen-masses solitary in the 

 sacs, pendulous on their caudicles. Stigma nearly flat, 5-angled or 5-lobed. Follicles 

 acuminate. Seeds compressed, comose. [Name in honor of the ancient Greek physician 

 Aesculapius.] 



A genus of about 90 species, natives of the western hemisphere. Type species, Asclepias syriaca L. 



Hoods without horn-like processes on the inner surface; leaves broad; pedicels deflexed in fruit. 



Herbage green and appearing glabrous, but usually minutely puberulent under a hand lens; hoods oblong- 



cylindric, open down the inner side. 1. A. cordifolia. 



Herbage densely white-woolly; hoods spheroid, open at the apex and half to two-thirds the way down 



the back. 2. A. calif ornica. 



Hoods with horn-like processes on the inner surface. 



Hoods about equaling the stamens and stigmas. 



Pedicels deflexed in fruit; leaves lanceolate-ovate or broader. 



Corolla-lobes over 10 mm. long; column none; horns subulate- falcate, included. 



3. A. cryptoceras. 

 Corolla-lobes not over 10 mm. long; column present. 



Lateral umbels sessile or subsessile; horns not exserted, rather blunt at apex; filament- 

 column with a pair of slender erect teeth subtending the anther-wings. 



4. A. vestita. 



Lateral umbels well-peduncled; horns subulate and acute at apex; filament-columns without 

 teeth. 

 Leaves often in whorls of three; horns but slightly exserted. 5. A. eriocarpa. 



Leaves opposite; horns well-exserted, sickle-shaped and incurved over tlir sninmit of the 

 stigmas. 6. A. erosa. 



Pedicels erect in fruit; leaves narrowly linear to narrowly lanceolate. 



Stems herbaceous, green; leaves persistent. 7. A. mexicana. 



Stems shrubby, white; leaves early deciduous. 8. A. albicans. 



Hoods two or three times as long as the stamens and stigmas; pedicels deflexed in fruit. 



Hoods open, plane, lanceolate above the broad base; leaves broadly ovate. 9. A. speciosa. 



Hoods with their sides closely appressed; horn attached toward the apex of the hood. 



Leaves broad; stems herbaceous, decumbent. 10. A . nyctaginifolia. 



Leaves almost filiform, often wanting; stems erect, often woody below. 11. A. subulata. 



