ASCLEPIADACEAE. 229 



stigma than in Apocynaceae, the filament-appendages forming a crown. 

 Gynoecium of 2 carpels with the stigmas united: one carpel usually 

 maturing. 



Erect or spreading herbs : pollinia pendulous : stigma neither saucer-shaped nor cup- 

 shaped. 



Hoods of the crown without horns. 1. ACERATES. 



Hoods of the crown each with a projecting horn. 2. ASCLEPIAS. 



Vines : pollinia horizontal : stigma saucer-shaped or cup-shaped. 3. VINCETOXICUM. 



1. ACERATES Ell. Erect or spreading herbs, with narrow or relatively 

 narrow leaf -blades. Calyx-lobes 5. Corolla rotate: lobes reflexed. Hoods of 

 the crown approximate to the anthers, the column very short or stout. 



1. A. viridiflora (Eaf.) Eaton. Plants 2-6 dm. tall: leaf -blades oval to 

 oblong, 4-6 cm. long: corolla-lobes 5-6 mm. long: hoods 3-4 mm. long: 

 column very short: anther-wings about 4 mm. long: pollinium-bodies 2-3 mm. 

 long: seed-coma 2.5-3 cm. long. 1ST. S. Common, in dry soil. Sandstones 

 and shales, schists, and especially common in serpentine. Sum. GREEN- 

 MILKWEED. 



2. ASCLEPIAS [Tourn.] L. Erect or spreading herbs, with narrow or 

 broad leaf -blades. Calyx-lobes 5. Corolla rotate: lobes reflexed. Hoods of 

 the crown (corona) approximate to the anthers, or nearly so, not adnate to the 

 anther- column, the horn mainly adnate only to the base of the hood. Anther- 

 wings salient at the base. Pollinia longer than the caudicles. Sum. 

 MILKWEED. SILKWEED. 



Corolla and hoods orange-yellow : leaves, or some of them, alternate. 



Stems decumbent or procumbent : leaves, at least the upper ones, opposite ; blades 



mainly oblong. 1. A. decumbens. 



Stems erect or ascending : leaves mainly alternate ; blades 



lanceolate-oblong to linear-lanceolate. 2. A. tuberosa. 



Corolla and hoods red, purple, green or white : leaves oppo- 

 site or whorled. 

 Leaf-blades broad. 



Follicles erect on deflexed pedicels. 



Leaf-blades sessile and sometimes clasping. 



Leaf-blades rounded or abruptly narrowed at 

 the apex : hoods broad, truncate and blunt- 



mucronate, the horn exserted. 3. A. amplexicaulis. 



Leaf-blades acuminate : hoods narrow, obtuse 



or acutish, the horn not exserted. 4. A. rubra. 



Leaf-blades petioled. 

 Corolla colored. 



Corolla dark-purple : hoods narrow, obtuse : 



petals less than twice as long as the crown. 5. A. purpurescens. 

 Corolla paler : hoods broad, truncate or 

 broadly rounded : petals over twice 

 as long as the crown. 

 Leaf-blades not acuminate at both ends : 

 hoods rounded and slightly auricled, 

 the horns scarcely exserted. 6. A. syriaca. 



Leaf-blades decidedly acuminate at both 

 ends : hoods truncate and prominently 

 auricled, the horns long exserted. 7. A. exaltata. 



Corolla white. 8. A. variegata. 



Follicles erect on erect pedicels. 



Leaves all opposite : hoods slightly auricled. 



Leaf-blades typically lanceolate or oblong-lan- 

 ceolate : plant glabrous or puberulent. 9. A. incarnata. 

 Leaf -blades typically oblong : plant copiously 



pubescent. 10. A. pulcUra. 



Leaves, at least the main ones, whorled in 4's 



or 6's : hoods prominently auricled. 11. A. quadrifoUa. 



Leaf-blades narrow, linear or nearly so, usually elongate. 12. A. verticillata. 



1. A. decumbens L. Stems decumbent or procumbent, 3-6 dm. long, hirsute or 

 hispid: leaf -blades mainly oblong above the more or less hastate base, 3-19 cm. 



