ASCLEPIADACE.fi. (MILKWEED FAMILY.) 343 



2. Anther-wings broadly rounded at base and conspicuously auriculate-notched 



just above it ; hoods with a minute horn exserted from the 2-lobed apex. 

 18. A. stenoph^lla, Gray. Puberulent, but foliage glabrous; stems 

 slender (1-2 high), leaves narrowly linear (3-7' long, l-2" wide), the 

 upper alternate, lower opposite; umbels several, short-peduncled, 10- 15-flow- 

 ered; corolla-lobes oblong, greenish; hoods whitish, equalling the anthers, 

 conduplicate-concave ; follicles erect on ascending pedicels. Dry prairies, 

 Neb. to E. Kan., south and westward. 



3. ACERA.TES, Ell. GREEN MILKWEED. 



Nearly as in Asclepias ; but the hoods destitute of crest or horn (whence the 

 name, from a privative, and Kpas, a horn). Flowers greenish, incompact 

 many-flowered umbels. Leaves opposite or irregularly alternate, short-peti- 

 oled or sessile. Pollen-masses slender-stalked. Follicles smooth, slender. 



# Crown upon a short column and shorter than the globular mass of anthers and 



stigma ; leaves mainly alternate-scattered. 



1. A. longifdlia, Ell. Minutely roughish-hairy or smoothish; stem 

 erect (1 -3 high), very leafy; leaves linear (3-7' long); umbels lateral, on 

 peduncles of about the length of the slender pedicels ; flowers 3" long when 

 expanded. Moist prairies and pine-barrens, Ohio to Minn., south to Fla. and 

 Tex. July -Oct. 



* * Crown sessile, the oblong hoods nearly equalling the anthers ; leaves often 



opposite and broader. 



2. A. Viridifl6ra, Ell. Minutely soft-downy, becoming smoothish ; stems 

 ascending (1-2 high); leaves oval to linear, thick (l|-4' long); umbels 

 nearly sessile, lateral, dense and globose ; flower (when the corolla is reflexed) 

 nearly -|' long, short-pedicelled. Dry soil, common, especially southward. 

 July - Sept. Runs into var. LANCEOL\TA, Gray, with lanceolate leaves 2- - 4' 

 long ; and var. LiNE\ins, Gray, with elongated linear leaves and low stems ; 

 umbels often solitary. The latter form from Minn., N. Dak., and southward. 



3. A. lanugindsa, Decaisne. Hairy, low (5-1 2' high) ; leaves lanceo- 

 late or ovate-lanceolate ; umbel solitary and terminal, peduncled ; flowers 

 smaller; pedicels slender. Prairies, N. 111. to Minn., and westward. July. 



4. ENSLENIA, Nutt. 



Calyx 5-parted. Corolla 5-parted ; the divisions erect, ovate-lanceolate. 

 Crown of 5 free membranaceous leaflets, which are truncate or obscurely lobed 

 at the apex, where they bear a pair of flexuous awns united at base. Anthers 

 nearly as in Asclepias ; pollen-masses oblong, obtuse at both ends, fixed below 

 the summit of the stigma to the descending glands. Follicles oblong-lanceo- 

 late, smooth. Seeds with a tuft, as in Asclepias. A perennial twining herb, 

 smooth, with opposite heart-ovate and pointed long-petioled leaves, and small 

 whitish flowers in raceme-like clusters, on slender axillary peduncles. (Dedi- 

 cated to A. Enslen, an Austrian botanist who collected in the Southern United 

 States early in the present century.) 



!. E. albida, Nutt. Climbing 8-12 high; leaves 3 - 5' wide. River- 

 banks, S. Penn. and Va. to 111., Mo., and Tex. July -Sept. 



