ASCLEPIADACE^. (MILKWEED FAMILY.) 343 



§ 2. Anther-wings hroadli/ rounded at base and conspicuously auriculate-iiotched 

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

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

 slender (1-2° liigli) , leaves narrowly linear (3-7' long, 1-2|" wide), the 

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

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

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

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



3. ACERATES, Ell. Green Milkweed. 



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

 name, from a privative, and K4pas, 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 



stif/r/t(i , leaves mainly alternate-scattered . 



1. A. longifolia, 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 Avhen 

 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. viridiflbra, Ell. Minutely soft-downy, becoming sinoothish; stems 

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

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

 nearlv Y ^o^S> short-pedicelled. — Dry soil, common, especially southward. 

 July - Sept. — Runs into var. laxceolXta, Gray, with lanceolate leaves 2| - 4' 

 long; — and var. lixeAris, Gray, witli elongated linear leaves and low stems; 

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



3. A. lanuginosa, Decaisne. /^a?Vy, low (5- 12' high) ; leaves lanceo- 

 late or ovate-lanceolate ; umbel solitary and terminal, pednncled ; 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 obscurelv 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 1)<)tanist who collected in the Southern United 

 States early in the present century.) 



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

 banks, S Penn. and Va. to 111.. Mo., and Tex -Tnly-SeDt. 



