230 ASCLEPIADACE^E. 



ASCLEPIAS. MILKWEED. 



Character of the Genus. Calyx 5-parted, persistent, the lobes small, 

 spreading. Corolla deeply 5-parted, the lobes bent downward toward the 

 stalk ; within the petals are 5 hooded processes, each with an incurved 

 horn, forming what is called the crown, and enclosing the stamen-tube. 

 Stamens 5, inserted in the base of the corolla ; filaments united into a tube 

 which encloses the pistil ; anthers adherent to the stigina, each with 2 

 vertical cells, each cell containing a flattened pear-shaped mass of pollen. 

 Ovaries 2 ; styles united ; stigma 1, fleshy, 5-angled. Follicles 2, one of 

 them often abortive, ovate or somewhat curved, spindle-shaped ; seeds nu- 

 merous, tufted with soft silky hairs. 



Perennial herbs with thick, deep-growing roots. Flowers terminal or 

 lateral in simple, many-flowered umbels. 



Asclepias cornuti Decaisne (A. Syriaca Linne). Milkweed, Silkweed. 



Description. Hoods of the crown ovate, obtuse, with a lobe or tooth 

 on each side of the short and stout horn. Pods ovate, woolly, and rough, 

 with soft spines. Stem simple, erect, stout, 3 to 4 feet high. Leaves op- 

 posite, oblong-ovate, with short petioles, smooth above, minutely downy 

 beneath, pale green. Umbels many-flowered, terminal and lateral in 

 pedicels shorter than the leaves ; flowers greenish-purple, appearing in 

 midsummer. 



Habitat. Common everywhere. 



Asclepias incarnata Linne. Swamp Milkweed. 



Description. Hoods of the crown scarcely as long as the slender, 

 pointed horn. Pods commonly smooth and glabrous. Stem erect, branch- 

 ing, 2 to 3 feet high, leafy to the top. Leaves opposite, oblong-lanceolate, 

 acute or pointed, obtuse or obscurely cordate at the base, with short peti- 

 oles. Umbels numerous, erect, mostly terminal, often in opposite pairs ; 

 flowers rose-purple, appearing in midsummer. 



A somewhat variable species, sometimes more or less hairy-pubescent, 

 again nearly smooth. 



Habitat. In wet, swampy places ; common. 



Asclepiastuberosa lArmv.Butterjlyweed Pleurisy-Root. 



Description. Hoods of the crown narrowly oblong, scarcely longer than 

 the nearly erect, slender, pointed horns, bright orange; corolla lobes 

 greenish-orange. Pods lanceolate, hoary. Stems numerous from a large 

 fleshy rhizome, 1 to 2 feet high, very leafy. Leaves numerous, scattered, 

 some of them opposite, oblong-lanceolate or linear, sessile or short-petioled. 

 Umbels corymbose at the summit of the stem and branches ; flowers very 

 showy, appearing late in summer. 



Habitat. In dry fields, and along roadsides ; common southward. 



Part Used. The root of A. tuberosa United States Pharmacopoeia. 

 The roots of A. incarnata and A. cornuti were formerly official, but were 



