398 ASCLEPIADACE2E. (MILKWEED FAMILY.) 



hoods of the crown roundish-oval, about half the length of the incurved claw- 

 shaped horns ; pods smooth. Dry hills : common, especially southward. 



2. ACERATES, Ell. GREEN MILKWEED. 



Nearly as in Asclepias ; but the hoods of the crown destitute of a horn 

 (whence the name, from a privative and nepas, -aroy, a horn). Flowers green- 

 ish. Leaves varying from opposite to irregularly alternate, short-petioled or 

 sessile. Pollen-masses slender-stalked. 

 1. Divisions of ike. corolla reflexed, oblong : hoods of the crown erect and concave : 



umbels compactly many-flowend : pods not muricate, slender. 

 * Crown not elevated; its hoods oblong, nearly equalling the anthers. 



1. A. viridifl6ra, Ell. Minutely soft-downy, becoming smoothish ; stems as- 

 cending (l-2 high) ; leaves varying from oval to linear, thick (l^'-4' long), 

 umbels nearly sessile, lateral, dense and globose ; flower (when the corolla is re- 

 flexed) nearly ' long, short-pedicelled. Dry soil : common, especially south- 

 ward. July - Sept. 



2. A. lanuginbsa, Decaisne. Hairy, low (5' -12' high) ; leaves lanceolate 

 or ovate-lanceolate ; umbel solitary and terminal, peduncled ; flowers not larger 

 than in the next ; pedicels slender. (Probably Asclepias lanuginosa, Nutt. : cer- 

 tainly A. Nuttalliana, Torr. Acerates monocephala, Lapham, in Ed. 2, addend.) 

 Prairies, Wisconsin (Lapham) and westward. July. 



# # Crown short-stalked, i. e. elevated above the base of the corolla ; its hoods oval, 

 strongly concave, and decidedly shorter than the tips of the anthers. 



3. A. longifolia, Ell. Minutely roughish-hairy or smoothish; stem 

 erect (1 -3 high), very leafy ; leaves mostly alternate-scattered, linear (3'-7' 

 long) ; umbels lateral, on peduncles of about the length of the slender pedicels ; 

 flowers 3" long when expanded. Moist prairies, Ohio to Wisconsin and south- 

 ward. July - Oct. 



2. ANANTHERIX, Nutt. Divisions of the corolla ascending or barely spread- 

 ing : hoods of the crown widely spreading and somewhat incurved, slipper-shaped 

 and laterally compressed, the cavity divided at the apex by a crest-like partition : 

 umbels solitary and terminal or corymbed, loosely-flowered: pods oblong or ovate, 

 often somewhat muricate with soft spinous projections. 



4. A. paniculata, Decaisne. Almost glabrous; stems short (lhigh); 

 leaves alternate, short-petioled, elongated-oblong, l'-2' wide; umbels several in 

 a cluster, short-peduncled ; flowers large (!' in diameter), green, with a purplish 

 crown. Prairies, Illinois ( Vasey, Bebb), and southward. June. 



3. ENSLENIA, Nutt. ENSLENIA. 



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 their base. An- 

 thers nearly as in Asclepias : pollen-masses oblong, obtuse at both ends, fixed 

 below the summit of the stigma to the descending glands. Pods oblong-lanceo- 

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



