386 ASCLEPIADACEAE (MILKWEED FAMILY) 



corolla greenish- white, 3-3.5 mm. long; lobes erect or nearly so: follicles 

 12-15 cm. long. Throughout the United States. 



2a. Apocynum cannabinum lividum (Greene) A. Nels. Habit, size, and 

 leaf characters the same, glabrous: calyx-lobes only half as long as the nar- 

 rowly campanulate corolla. (A. lividum Greene, PI. Baker. 16. 1901.) 

 Wyoming and Colorado. 



3. Apocynum hypericifolium Ait. Hort. Kew 1: 304. 1789. Not strongly 

 differentiated from A. cannabinum: leaves usually broader, with rounded or 

 subcordate base, subsessile, often abruptly apiculate. New Mexico to Mon- 

 tana and the Great Lakes. 



95. ASCLEPIADACEAE Lindl. MILKWEED FAMILY 



Mostly herbs with milky juice, usually opposite leaves without stipules, 

 and regular perfect flowers in terminal or pseudo-axillary or sometimes axil- 

 lary cymes (often umbelliform) . Calyx free from the ovary or nearly so, im- 

 bricated in the bud. Corolla 5-merous, convolute, or often nearly valvate 

 in the bud. Stamens 5, borne on the tube of the corolla and alternate with 

 its lobes ; anthers surrounding the stigma ; pollen in 1 or 2 waxy masses, in 

 ours all the pollen in each cell in one mass and attached to the stigmatic 

 disk by the glands that alternate with the anthers. A crown of 5 parts or 

 lobes usually present between the corolla and the mostly monadelphous 

 stamens, and adnate either to the one or the other. Ovary of 2 cells that 

 become several to many-seeded follicles. Seeds almost always bearing a 

 long and soft coma. 



Lobes of the corolla reflexed at anthesis. 



Leaves alternate or opposite; hoods of the crown crestless . . .1. Acerates. 



Leaves mostly opposite; hoods of the crown each with an incurved horn 2. Asclepias. 

 Lobes of the corolla erect at anthesis; leaves alternate; hoods of the 



crown prominently crested ........ 3. Asclepiodora. 



1. ACERATES Ell. GREEN MILKWEED 



Perennial herbs, with thick leaves and green or purplish flowers in short- 

 peduncled or sessile umbels. Calyx 5-parted or 5-divided, the segments acute, 

 glandular within. Corolla deeply 5-cleft, the segments valvate, reflexed in 

 anthesis. Crown-column very short; crown of 5 involute-concave or some- 

 what 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. Stigma 5-lobed. 



Leaves numerous, alternate-scattered; auricles of the hoods conspicuous 1. A. auriculata. 

 Leaves in part opposite; auricles of the hoods concealed or wanting. 



Hoods entire . . . . . . . . . . . 2. A. viridiflora. 



Hoods trilobed 3. A. angustifolia. 



1. Acerates auriculata Engelm. Bot. Mex. Bound. 160. 1859. Glabrous up 

 to the inflorescence; stem 5-8 dm. high, slender: leaves linear-filiform, with 

 scabrous margins: umbels several, lateral: column below the hoods very 

 short; hoods oval or quadrate, emarginately or sometimes 3-crenately trun- 

 cate, the involute margins at base appendaged with a pair of remarkably large 

 and broad auricles: anther- wings narrow and of equal breadth from top to 

 bottom. Colorado and Kansas to Texas and New Mexico. 



2. Acerates viridiflora (Raf.) Eaton, Man. Ed. 5. 90. 1829. Tomentose- 

 puberulent; stem 2-5 dm. high: leaves oval or oblong and obtuse or retuse, 

 or sometimes narrower and acute: umbels 2-5 or sometimes solitary, dense, 

 mostly lateral and subsessile; pedicels little over twice the length of the re- 

 flexed narrowly oblong lobes of the greenish corolla: hoods somewhat fleshy, 



