354 asclepiadace^e. (milkweed family.) 



purple; hoods of the crown (flesh-color) ovate, about the length of the ascend- 

 ing or scjthe-form awl-shaped horns; pods veiny, smooth. — Varies with the 

 leaves a little heart-shaped at the base, and, in var. pulchra, with broader and 

 shorter-petioled leaves, more or less hairy-pubescent, as well as the stem. (A. 

 pulchra, Willd.) — Wet grounds; the smooth form very common northward; 

 the hairy variety more so southward. July, Aug. — Milky juice scanty, 

 -t- -i- Leaves alternate-scattered, or the lowest opposite : milky juice little or none. 



13. A. tial>erdsa, L. (Butterfly-weed. Pleurisy-root.) Rough- 

 ish-hairy; stems erect or ascending, very leafy, branching at the summit, and 

 bearing the umbels in a terminal corymb ; leaves varying from linear to oblong- 

 lanceolate, sessile or slightly petioled ; divisions of the corolla ovate-oblong 

 (greenish-orange) ; hoods of the crown narrowly oblong, bright orange, scarcely 

 longer than the nearly erect and slender awl-shaped horns ; pods hoary. (A. 

 dccunibens, L.) — Dry hills and fields ; common, especially southward. July- 

 Sept. — Plant 1°- 2° high, leafy to the summit, usually with numerous and 

 corymbed short-peduncled umbels of very showy flowers, which are rather 

 smaller than in No. 1. 



■t- ■*- ■*- Leaves nearly all whorled, rarely alternate, crowded. 



14. A. verticillitta, L. (Whorled Milkweed.) Smoolhish ; stems 

 slender, simple or sparingly branched, minutely hoary in lines, very leafy to the 

 summit; leaves very narrowly linear, with revolutc margins (2'-3' long, 1" 

 wide), 3-G in a whorl ; umbels small, lateral, and terminal ; divisions of the co- 

 rolla ovate (greenish-white) ; hoods of the crown roundish-oval, about half the 

 length of the incurved claw-shaped horns; pods very smooth. — Dry hills; 

 common, especially southward. July -Sept. — Flowers small. 



2. ACS'} RATES, Ell. Green Milkweed. 



Nearly as in Aselepias ; but the concave upright hoods of the crown desti- 

 tute of a horn (whence the name, from a privative and aepac, -a-oc, a horn). 



1. A. viridifldra, Ell. Downy-hoary; stems loiv and stout, ascending; 

 leaves varying from oval or obovate to lanceolate or almost linear, slightly peti- 

 oled, mucronate-acute or obtuse, thick, at length smoothish ; umbels nearly sessile, 

 densely many-flowered, globose, lateral ; divisions of the corolla oblong; hoods of 

 the crown oblong, strictly erect, sessile at the base of the tube of filaments, short- 

 er than the anthers ; pods nearly smooth. (Aselepias viridifiora, Pursh. A. 

 lanceolata, Ives. A. obovata, Ell.)— Dry hills and sandy fields; common, es- 

 pecially southward. July - Sept. — Flowers greenish; when expanded, about 

 the length of the pedicel. Leaves singularly variable in form. 



2. A. longifolia, Ell. Minutely hoary or rough-hairy ; stem slender, up- 

 right (l°~2i° high) ; leaves elongated-linear (3' -7' long, i'-# wide) ; umbels 

 pedunc/ed, open, many-flowered ; divisions of the corolla ovate-oblong, several 

 times shorter than the pedicels ; hoods of the crown short and rounded, raised on 

 the tuba of filaments ; pods smooth. — Moist places, Ohio to Wisconsin and south- 

 ward. June, July. — Flowers half as large as in the last, tinged with yellowish. 



A monocephala and A. paniculata ; see Addend. 



