ASCLEPIADACE^.. (mILKWEKD FAMILY.) 343 



§ 2. Anther-wings broadly rounded at base and conspicuouslt/ auriculate-notched 

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

 18. A. stenophylla, Gray. Pubemlent, but foliage glabrous; stems 

 slender (1-2° lii^li) , leaves narrowly linear (3-7' long, l-2f wide), the 

 upper alternate, lower o])posite ; umbels several, short-pedunclcd, 10- 15-flow- 

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

 conduplicate-coneave ; follicles erect on ascending pedicels. — Dry prairie.s, 

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



3. ACERATES, Ell. Green Milkweed. 



Nearly as in Asclei)ia5 ; but the hoods destitute of crest or horn (whence the 

 name, from a ])rivative, and Kfpas, a horn). — Flowers greenish, incompact 

 many-Howered 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. longifolia, Ell. Minutely roughish-hairy or smoothish ; stem 

 erect (1-3° lii^li), \ery leafy; leaves linear (3 -7' long); umbels latei-al, 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. viridiflbra, Ell. 'M\\mtQ\\ soft-downy, becoming smoothish; 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) 

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

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

 long; — and var, lixeXuis, Gray, with elongated linear leaves and low stems; 

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



3. A. lanugindsa, Decaisne. //a »7/, low (5-12' high); leaves lanceo- 

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

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



4. ENSLENIA, Xutt. 



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 jiair of flexuous awns united at base. Anthers 

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

 the summit of tiie 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.) 



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

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



