398 ASCLEPIADACE^. (lIILKWEED FAMILY.) 



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

 bhapcd horns; pods smooth. — Dry hills: common, especially southwurd. 



2. ACERATES, Ell. Green Milkweed. 



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

 (whence the name, from a pricativt and Ktpai, -gtoj, a horn). — Flowers green- 

 ish. Leaves varying from opjjosite to irregularly alternate, short-petiolcd or 

 sessile. Pollen-masses slender-stalked. 



§ 1 . Divisions of the corolla rejiexed, oblong : hoods of (he crown erect and concace : 



umbels compactly manij-Jioivejtd : pods not muricate, slender. 



* Crotcn not elevated; its hoods oblony, neailij equalling the anthers. 



1 . A. Viridifldra, Ell. Minutely sofi-downtj, becoming smoolhish ; 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- 

 fle.\ed) nearly V long, short-pedicelled. — Dry soil : common, especially south- 

 ward. July - Sept. 



2. A. lanugindsa, Dccaisne. //aZ/v/, low (5' -12' high) ; leaves lanceolate 

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

 than in the next ; pedicels slender. (Probably Ascle[)ias lanuginosa, Nntt. : cer- 

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

 — 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. longif61ia, 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 tiic slender pedicels; 

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

 ward. July -Oct. 



§2. ANANTIIERIX, 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-Jiowend : pods oblong or ovate, 

 often somewhat muricate with sofl spinous projections. 



4. A. paniculata, Decaisne. Almost glabrous; stems short (l°high); 

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

 a chister, short-peduncled ; flowers large (1' in diameter), green, with a purplish 

 crown. — Prairies, Illinois [Vasey, Bebb), and southward. June. 



3. ENSLENIA, Xutt. Exslenia. 



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

 Crown of 5 free membranaceous leaflets, which are trnncate or obscurely lobcd 

 at the apex, where they bear a pair of flexuous awns united at their base. An- 

 thers nearly as in Ascle))ias : pollen-masses oblong, obtuse at both ends, fixed 

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

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



