ASCLEPIADACEAE. 



VOL. III. 



3. ACERATES Ell. Bot. S. C. & Ga. i: 316. 1817. 



Perennial herbs, similar to Asclepias, with alternate or opposite thick leaves, and green 

 or purplish flowers in terminal or axillary and short-peduncled or sessile umbels. Calyx 

 5-parted or 5-divided, the segments acute, glandular within. Corolla deeply 5-cleft, the seg- 

 ments valvate, reflexed in anthesis. Corona-column very short. Corona of 5 involute-concave 

 or somewhat pitcher-shaped hoods, neither horned nor crested within or in one species having 

 a small interior crest and usually a few small processes at the base of the anther-wings, 

 forming an obscure inner crown. Pollen-masses solitary in each sac, oblong, pendulous. 

 Stigma 5-lobed. [Greek, without horn, referring to the crown.] 



About 7 species, natives of North America. Type species : Acerates longifolia (Michx.) Ell. 



Umbels sessile, or very nearly so, mostly axillary. 



Leaves oval to linear ; hoods entire at the apex. i. A. viridiflora, 



Leaves narrowly linear ; hoods 3-toothed. 2. A. angustifolia. 



Umbels, at least the lower, distinctly peduncled. 



Plants glabrous, or nearly so ; umbels usually several ; leaves narrow. 



Hoods obtuse, entire; column y 2 " long; stem roughish puberulent. 3. A. floridana. 



Hoods emarginate ; column very short ; stem glabrous. 4. A. auriculata. 



Plant hirsute ; umbel solitary, terminal ; leaves- ovate to oblong. 5. A. lanuginosa. 



i. Acerates viridiflora (Raf.) Eaton. Green Milkweed. Fig. 3409. 



Asclepias viridiflora Raf. Med. Rep. (II.) 5 : 360. 1808. 

 Acerates viridiflora Eaton, Man-. Ed. 5, 90. 1829. 



Puberulent or tomentulose, at least when young; 

 stems simple, reclined or ascending, rather st.ff, 

 i-3 high. Leaves slightly rough, alternate or op- 

 posite, thick, oval, oblong or ovate to lanceolate or 

 linear, 1'-$' long, \'-2.' wide, short-petioled, the mar- 

 gins usually undulate ; umbels several, or rarely 

 solitary, axillary, densely many-flowered, sessile or 

 very nearly so ; pedicels very slender, tomentose, 

 4"-8" long; flowers green; corolla-segments nar- 

 rowly oblong, 2"-3" long ; column very short or 

 none; hoods lanceolate-oblong, obtuse, minutely 

 2-auricled at the base; mass of anthers longer than 

 thick ; anther-wings tapering below, semi-rhomboid 

 above; follicles puberulent, 2'-^' long. 



In dry, sandy or rocky soil, Massachusetts to south- 

 ern Ontario, Saskatchewan, Florida and Texas. Con- 

 sists of several races, differing mainly in leaf-form. 

 June-Sept. 



2. Acerates angustifolia (Nutt.) Dec. 

 Narrow-leaved Milkweed. Fig. 3410. 



Polyotus angustifolius Nutt. Trans. Am. Phil. Soc. 

 (II.) 5= 201. 1833-37. 



A. angnstifolia Dec. in DC. Prodr. 8: 522. 1844. 



Asclepias stenophylla A. Gray, Proc. Am. Acad. 12 : 

 72. 1876. 



Stems mostly several together, erect, straight, 

 i-2 high, puberulent above, glabrate below. 

 Leaves opposite, or some of the lower alternate, 

 sessile, narrowly linear, 2'-5' long, glabrous, the 

 revolute margins and the thick midvein rough 

 beneath ; umbels io-is-flowered, short-peduncled 

 or subsessile, axillary, usually numerous ; pedicels 

 puberulent ; corolla-segments oblong, greenish ; 

 hoods white, not exceeding the anthers, 3-toothed 

 at the apex, the acute middle tooth merely a 

 prolongation of the thickened crest-like midvein, 

 shorter than the obtuse lateral ones ; anther- 

 wings notched at about the middle ; follicles 

 slender, erect, about 3' long or more. 



On dry plains, Missouri, Nebraska and Colorado to 

 Texas. 



