196 KEY AND FLORA 



I. ASCLEPIODORA Gray. 



Plants much like Asclepias, but the hoods without horns. 

 Lobes of the corolla ascending or spreading. 



1. A. viridis Gray. Gkeen Milkweed. Stems about 1 ft. high, 

 nearly smooth. Leaves alternate, short-petioled, oblong to ovate- 

 lanceolate. Umbels clustered. Flowers about 1 in. in diameter, 

 green with a purplish crown. In dry soil W. and S. 



II. ASCLEPIAS L. 



Perennial herbs. Mowers in simple (usually many-flowered) 

 umbels. Calyx small, 5-parted, its lobes reflexed. Corolla deeply 

 5-parted, with reflexed lobes ; crown of hoods and horns con- 

 spicuous (Fig. 27, A, B). Stamens with their filaments united 

 into a tube around the pistil and anthers attached to the stigma 

 (Fig. 27, D, E) ; anther cells 2, each cell containing an elon- 

 gated, pear-shaped, tough mass of pollen, a mass from one 

 anther always paired with one from the adjoining anther and 

 each two together suspended from one of the 5 split glands 

 on the angles of the stigma (Fig. 27, D, E). Ovaries 2 ; styles 

 very short. Pods 2 or sometimes 1 and the other undeveloped. 

 Seeds flat, each with a tuft of long, silky hairs. The flowers 

 are pollinated by insects, which get their feet entangled in 

 the clefts of the glands (Fig. 27, g) and then carry off the 

 pollen masses. 



1. A. tuberosa L. Butterfly Weed, Pleurisy Root. Stems 

 roughish-hairy, 1-2 ft. high. Juice not milky. Leaves abundant, 

 linear to lanceolate-oblong. Flowers showy, usually bright orange, 

 in terminal cymose umbels. Horns nearly erect and slender. Pods 

 nearly erect, covered with fine down. In dry fields. 



2. A. decumbens L. Reclining Butterfly Weed. Much resem- 

 bling A. tuberosa, but the ste6is reclining with the ends erect. Leaves 

 elliptic or oblong. Umbels racemed along the branches. In dry soil. 



3. A. purpurascens L. Purple Milkweed. Stem 1-3 ft. high, 

 somewhat branched above. Leaves 4-6 in. long, elliptical or nearly 

 so, the upper ones taper-pointed, slightly velvety beneath, short- 

 petioled. Umbels terminal. Flowers J in. long, dark purple ; pedi- 

 cels shorter than the peduncle ; horn broadly scythe-shaped, with the 

 point bent sharply inward. Dry soil. 



