Order 97.— ASCLEPIADS. 



273 



by the middle. Follicles long, slen- 

 der, separate. Seeds with a tuft of 

 long, silky down. June-August. 



1 A. androsaemifo'lium. Tutsan-leaved D. 



Corolla rose-wliitc, much longer than 

 the calyx. Leaves ovate. Plant 

 smooth, elegant, about 3f. high. 



2 A. cannabi'num. Hemp D. Cor. green- 



ish-white, scarce longer than tho 

 calyx. Leaves oblong. Bark tough 

 as hemp. 



Fig. 620. Common Dog*s-bane. 1. A flower 

 of the natural size. 2. The flower cut open, 

 showing the peculiar stamens. 3. The 2 styles 

 and stigmas. 4. The plan of the flower. 5. The 

 2 follicles. 6. A seed with its tuft of silk. 





Order XCYII. ASCLEPIADACE^. Asclepiads. 



Plants (chiefly Jierbs in the United States) with a rmYkj juice ; 

 leaves opposite (rarely whorled or scattered), entire, without stipules ; 

 flowers generally umbeled, 5-parted, regular ; sepals and also the 

 petals united at base, both commonly valvate in the bud ; 

 stamens united into a fleshy mass with the two stigmas ; 

 pollen cohering in masses ; ovaries 2, iorvomg follicles in fruit 



Analysis of the Genera. 

 % Plants erect. Stamen-mass crowned with 5 little hoods. . . .2 



S Plants twining or prostrate 3 



2 Hoods each with a little projecting horn ... .a 



2 Hoods destitute of horns b 



8 Flowers dark purple c 



3 Flowers whitish or flesh-colored 



■ Petals reflexcd. Hoods erect, horns incurved. SiU-grass. Milkweed. Ascle^'pias. 1 

 b Petals reflexcd. Hoods erect, adnate to the anthers. Ackra^tes. 



b Petals spreading, green. Hoods free from the anthere. S. Anan'therix. 

 b Petals erect, yellowish. Mass of anthers stalked. S. Podostiq'ma. 



12* 



