740 FLORA. 



Family 6. ASCLEPIADACEAE Lindl.* 



Milkweed Family. 



Perennial herbs, vines or shrubs, mostly with milky juice, with esti- 

 pulate leaves, and mostly umbellate perfect regular flowers. Calyx infe- 

 rior, its tube very short, or none, its segments imbricated or separate in 

 the bud. Corolla campanulate, urceolate, rotate or funnelform, 5-lobed 

 or 5-cleft, the segments commonly reflexed. A 5-lobed or 5-parted 

 crown (corona) between the corolla and the stamens and adnate to 

 one or the other. Stamens 5, inserted on the corolla; filaments short, 

 stout, mostly monadelphous, or distinct; anthers attached by their 

 bases to the filaments, introrsely 2-celled, connivent around the stigma, 

 or more or less united with each other; anther-sacs tipped with an in- 

 flexed or erect scarious membrane, or unappendaged at the top, some- 

 times appendaged at the base; pollen coherent into waxy or granular 

 masses, one or rarely two such masses in each sac, connected with the 

 stigma in pairs or fours, by $ glandular corpuscles alternate with the 

 anthers. Disk none. Ovary of 2 carpels; styles 2, short, connected at 

 the summit by the peltate discoid stigma; ovules numerous in each 

 carpel, mostly anatropous, pendulous. Fruit of 2 follicles. Seeds com- 

 pressed, usually appendaged by a long coma; endosperm cartilagi- 

 nous ; embryo nearly as long as the seed ; cotyledons flat. About 220 

 genera and 1900 species of wide distribution. 



Erect or decumbent herbs. 



Corona-hoods each with an incurved horn within ; leaves mostly opposite. 



1. Asclepias. 

 Corona-hoods prominently crested within ; leaves alternate. 2. Asclepiodora. 



Corona-hoods unappendaged or with a thickened crest-like keel; leaves opposite 

 or alternate. 3. Acerates. 



Twining vines. 



Corolla-lobes erect; corona-lobes 1 -2-awned. 4. Gonolobus. 



Corolla rotate. 



Anthers tipped with a scarious membrane ; pollen-masses pendulous. 



5. Cynanchum. 

 Anthers merely tipped; pollen-masses horizontal. 6. Vincetoxicum. 



1. ASCLEPIAS L. (See Appendix.) 



Perennial herbs, with entire leaves, and middle-sized or small flowers in urn- 

 bels. Calyx 5-parted or 5-divided. usually small, the segments or sepals acute, 

 often glandular within. Corolla deeply 5-parted, the segments mostly valvate, 

 reflexed in anthesis. Corona-column generally present. Corona of 5 concave 

 hoods, each bearing within a slender or subulate incurved horn. Filaments con- 

 nate 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 nearly flat. 5 -angled or 5-lobed. Follicles usually thick, 

 acuminate. Seeds comose in all but one specie?. [Dedicated to AEsculapius.] 

 About 85 species, mostly natives of the New World; besides the following some 

 25 others occur in southern and western N. Am. 



* Corolla and corona orange : leaves alternate or opposite. 

 Stem erect or ascending; leaves nearly all alternate. 1. A. tuberosa. 



Stems reclining ; leaves, at least the upper, opposite, oblong or oval. 



2. A, decumbens. 

 * * Corolla bright red or purple: leaves opposite. 

 Flowers 2-4 mm. broad ; corona-hoods 4-6 mm. high. 



Leaves lanceolate or linear; hoods oblong, obtuse 3. A. lanceolata. 



Leaves ovate or ovate-lanceolate; hoods lanceolate. 4. A. rubra. 



Leaves oblong, ovate or ovate-oblong; hoods oblong, acutish. 5. A. purpurascens, 



* Revised by Miss Anna Murray Vail. 



