306 Asclepiadaceae 



1. PHILIBERTELLA Vail. 



Twining herbs or somewhat shrubby, with < >}>pi >-i t <* 

 Leaves and umbellate flowers. Calyx small. 5-parted, the 

 Lobes acute. Corolla campanulate or rotate, deeply 

 5-parted, the lobes acute or obtuse, with a shallow entire 

 or undulate ring forming an outer crown in its throat. 

 The inner staminal crown consisting of 5 turgid fleshy 

 or hard scales or flatfish appendages, attached in a circle 

 at the base of the sessile or slighly stalked column, 

 forming a hollow entire or undulate spreading surface 

 near the level of the conic stigmas. Follicles naked, 

 slender, attenuate at both ends or obtuse at base. 



1. P. Hartwegii heterophylla (Engelm.) Vail. Steins slen- 

 der, twining, glabrous, puberulent or somewhat pubescent above; 

 leaves 2.5-5 cm. long, 2-4 mm. wide, variable, some tapering into 

 the petiole, others with rounded and more with dilated or auricu- 

 late-cordate or truncate base; corolla scarcely puberulent, 1 cm. 

 broad, its lobes acute; column sessile. 



Occasional on dry hillsides in our interior valleys, growing over low 

 shrubs or herbs. 



2. ASCL.EPIAS L. Milkweed. 



Perennial erect or decumbent herbs, with opposite ver- 

 ticillate or rarely alternate' leaves, and flowers in ter- 

 minal or axillary umbels. Calyx 5-parted or 5-divided, 

 usually small, the lobes acute, often glandular within. 

 Corolla deeply 5-parted, the lobes most ly valvate. reflexed 

 in anthesis. Corona-column generally present. Corona 

 of ■"> concave, erect or spreading hoods, each bearing 

 within a slender or subulate incurved horn. Filaments 

 connate into a tube ; anthers tipped with an inflexed 

 membrane ; winged, the wings broadened below the 

 middle ; pollen-masses solitary in each sac, pendulous 

 on their caudicles. Stigma aearly flat, 5-aneled or 



