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* Crown upon a short column and shorter than the globular mass of anthers and stigma: 
leaves mainly alternate-scattered, very numerous. 
1. A. auriculata Engelm. Glabrous up to the inflorescence: stem 6 to 9dm. high: 
leaves linear-filiform, 10 to 15 cm. long, with scabrous margins: pedicels short: hoods 
oval or quadrate, emarginately or sometimes 3-crenately truncate, the involute mar- 
gins at base appendaged with a pair of remarkably large and broad auricles.—Prai- 
ries and rocky ground, from southern Texas to New Mexico and Colorado, likely to 
be confounded with Asclepias stenophylla. 
2. A. longifolia Ell. Minutely roughish-hairy or smoothish: stem erect, 3 to 9 
dm. high: leaves from linear to elongated-lanceolate, 7.5 to 20 cm. long: pedicels 
slender: hoods purple or purplish, oval, obtuse, entire, unappendaged.—Moist prai- 
ries and pine-barrens, extending from the Atlantic region into Texas, 
** Crown sessile, the oblong hoods nearly equaling themass of anthers and stigma (which 
is longer than broad): leaves often opposite and broader. 
3. A. viridiflora Ell. Minutely soft-downy, becoming smoothish: stems ascend- 
ing, 3 to 6 dm. high: leaves oval to linear, thick, 3.5 to 10 cm, long: umbels nearly 
sessile, lateral, dense, and globose: flowers short-pediceled.—Dry sterile soil, ex- 
tending from the Atlantic region to southern Texas, Runs into var. LANCEOLATA 
Gray, with lanceolate leaves 6.5 to 10 cm. long; and var. LINEARIS Gray, with elon- 
gated linear leaves, low stems, and often solitary umbels. 
5. ENSLENIA Nutt. 
A smooth perennial twining herb, with opposite cordate-ovate and 
pointed long-petioled leaves, small whitish flowers in raceme-like clus- 
ters on slender axillary peduncles, 5-parted calyx, 5-parted corolla with 
erect ovate-lanceolate divisions, crown of 5 freemembranaceous leaflets 
which are truncate or obscurely lobed at apex where they bear a pair 
of flexuous awns united at base, anthers nearly as in Asclepias, oblong 
pollinia obtuse at both ends and fixed below the summit of the stigma 
to the descending glands, and oblong-lanceolate smooth pods. 
1. BE. albida Nutt. Climbing high: leaves 7.5 to 12.5 cm. wide.—River banks, 
extending from the Atlantic region into Texas. 
6. ROULINIA Decaisne. 
Twining plants, with the aspect and growth of Enslenia, but with 
rotate-spreading corolla, 5-parted crown with divisions simply and ab- 
ruptly acuminate or ligulate-tipped, and tuberculiform and short anther- 
wings. 
1. R. unifaria Engelm. Leaves deeply cordate, abruptly slender-acuminate : cymes 
10 to 20-flowered, somewhat paniculate or racemiform: flowers greenish-white: 
pods oblong, thick, 7.5 to 10 cm. long.—Along the streams of southern and western 
Texas. 
7. METASTELMA BR. Br. 
Twining perennial glabrous herbs, with small opposite leaves, small 
white or greenish flowers in axillary umbelliform clusters, short calyx 
with obtuse lobes, campanulate 5-cleft or parted corolla with lobes 
commonly puberulent or bearded within, crown of 5 flat or slender dis- 
tinct scales or subulate processes (not tipped with any appendage or 
prolonged middle lobe) born on corolla or column, and smooth pods.—In 
ours the crown is borne on the base of the corolla or of the short coluinn. 
