Obdee 97.— ASCLEPIADS. 



273 



by the middle. Follicles long, slen- 

 der, separate. Seeds with a tuft of 

 long, sitfcy down. June-August. 



1 A. androsaemifo'limn. Tutsan-lemed D. 



Corolla rose-white, much longer than 

 the calyx. Leaves ovate. Plant 

 smooth, elegant, about Sf. high. 



2 A. cannaM'nnin. Hemp D. Cor. green- 



ish-white, scarce longer than the 

 calyx. Leaves oljlong. ■ 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. 8. Tlie 2 styles 

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

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



Order XCVIP. ASCLEPIADAOB.^. Asclepiads. 



Plants (chiefly herbs/ai the United States) with a nnikj juice ; 

 leavies 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 ; 

 sta?mens united into a fleshy mass with the two stigmas ; 

 pollen cohering in masses ; ovaries 2, iormmg follicles in fruit. 



Analysis of the Genera. 

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



§ Plants twining or prostrate 3 



2 Hoods ^ch *ith a little projecting horn. . . .a 



2 Hoods destitute of horns b 



8 Flowers dark purple c 



3 Flowers whitish or flesh-colored 



a Petals reilexed. Hoods erect, horns incurved. Silkgrass. Milhweed. Asole'pias. 

 b Petals reflexed. Hoods erect, adnate to the anthers. Aoera'tes. 



b Petals spreading, green. Hoods free from the anthers. S. Anan'thekix. 

 b Petals erect, yellowish. Mass of anthers stalked. S. PoDosraa'itA. 



13* 



