asclepiadace^e. (milkweed family.) 395 



an incurved horn. Stamens 5, inserted on the base of the corolla . filaments 

 united in a tube which encloses the pistil : anthers adherent to the stigma, each 

 with 2 vertical cells, tipped with a membranaceous appendage, each cell con- 

 taining a flattened pear-shaped and waxy pollen-mass ; the two contiguous pol- 

 len-masses of adjacent anthers, forming pairs which hang by a slender prolon- 

 gation of their summits from 5 cloven glands that grow on the angles of the 

 stigma,extricated from the cells by the agency of insects, and directing copious 

 pollen-tubes into the point where the stigma joins the apex of the stylcf. 

 Ovaries 2, tapering into very short styles : the large depressed 5-ahglcd fleshy, 

 mass which takes the place of stigma common to the two. Follicles 2, one of 

 them ofcen abortive, soft, ovate or lanceolate. Seeds anatropous, flat, margined, 

 downwardly imbricated all over the large placenta, which separates from the 

 suture at maturity, furnished with a long tuft of silky hairs (coma) at the hilum. 

 Embryo large, with broad foliaceous cotyledons in thin albumen. — Perennial 

 upright herbs, with thick and deep roots : peduncles terminal or lateral and be- 

 tween the petioles, bearing simple many-flowered umbels : flowering in summer. 

 (The Greek name of ^E 'scuta plus, to whom the genus is dedicated.) 



* Leaves opposite (or some of them in No. 5-7 in threes or fours.) 

 +- Stem simple or nearly so, leafy to the top, and bearing lateral umbels as well as a 



terminal one: leaves ovate or oblong : flowers whitish, pinkish, or dull purple. 

 ++ Pods beset with soft spinous projections: flowers 6" -9" long when open, greenish- 

 purple, numerous in dense umbels. 



1. A. Cornilti, Decaisne. (Common Milkweed or Silkweed.) Stem 

 tall and stout; leaves oval-oblong (4' -8' long), contracted at base into a short 

 petiole, pale, minutely downy beneath, as well as the peduncles, &c. ; hoods of the 

 crown ovate, obtuse, with a lobe or tooth on each side of the short and stout claw-like 

 horn ; pods ovate, covered with weak spines and woolly. (A. Syriaca, L., but the 

 plant belongs to this country only.) — Rich ground, everywhere. 



2. A. Sullivantii, Engelm. Very smooth throughout, tall ; leaves ovate- 

 oblong with a somewhat hart-shaped base, nearly sessile; hoods obovate, entire, ob- 

 tusely 2-(ared at the base outside; flowers larger (9" long) and more purple than 

 in the preceding ; pods obscurely soft-spiny, chiefly on the beak, ovate-lanceolate. 



— Low grounds, Columbus, Ohio (Sullivant) to Illinois. 



++ Pods even, not warty-roughened, mostly glabrous. 



3. A. phytolaccoides, Pursh. (Poke-Milkweed.) Stem (3° -5° 

 high) smooth ; leaves broadly ovate, or the upper oral-lanceolate and pointed at bo/h 

 ends, short-pet iol d, smooth or slightly downy underneath (5' -8' long) ; lateral 

 umbels several ; pedicels loose and nodding, numerous, long and slender (1' -3' long), 

 equalling the peduncle, many tinv-s longer than the ovate-oblong divisions of the (green- 

 ish) corolla ; hoods of the crown (white) truncate, the margins 2-toothed at the 

 summit, the horn with a long projecting awl-shaped point ; pods minutely downy. 



— Moist copses ; flowering early in summer. — Flower 6" long. 



4. A. purpurascens, L. (Purple M.) Stem rather slender (1°- 3° 

 high) ; leaves elliptical or ovate-oblong, the upper taper-pointed, minutely velcety- 

 downy underneath, smooth above, contracted at the base into a short petiole ; pedicels 



