150 ASCLEPIADACEAE 



3. A. pubescens R. Br. Resembles the last but the Avhole plant- 

 especially the lower surface of the leaves, is very velvety-pubescent. 

 Rather common in low grounds throughout. June-September. 



Family 101. ASCLEPIADACEAE LincU. 

 Plants with milky juice, entire, non-stipulate leaves and umbellate 

 flowers. Divisions of calyx and corolla five each. Stamens five, conni- 

 vent. Anthers 2-celled, each cell containing a waxy pollen mass. Osary 

 superior, 2-celled. Styles two, connected by the 5-angled stigma. Stigma 

 and pollen masses connected by five glandular bodies growing in the angles 

 of the stigma. Between the stamens and corolla there is a ring or a disk. 

 Fruit of two follicles. Seeds bearing a long coma. 



Corolla strongly reflexed. 



Crown of five hood-like bodies each bearing an in- 

 curved horn within. 1. ASCLEPIAS. 



Crown like the last, but hornless. 2. AcERATES. 



Corolla merely spreading. 



Herbs. 3. ASCLEPIODORA. 



Vines. 4. GoNOLOBUS. 



1. ASCLEPIAS L. JIlLKWEED. 



Erect perennial herbs. 



Leaves alternate, lanceolate. 1. A. tuberosa. 



Leaves opposite, broad. 

 Flowers rose-purple. 2. A . purpurascens. 



Flowers pinkish or yellowish-white. 



Leaves lanceolate. 3. A. incarnnia. 



Leaves ovate oblong. 

 Stems glabrous. 



Peduncles shorter than the leaves. 4. A. SuUivaniii. 



Peduncles much longer than the leaves. 5. A. (tmpJexicauUfi. 



Stems finely aoft-pubescent. 6. A. Syriaca. 



Leaves verticiilate, linear. 7. A. verticilUita. 



1. A. tuberosa L. Butterfly Weed. 1°-2° high, pubescent: 

 leaves nearly sessile, cordate at base: flowers deep orange-coloied in 

 numerous umbels : follicles erect on the decurved fruiting pedicels. — 

 Common in open fields and jjrairies. June-July. 



2. A. purpurascens L. Purple ISIilkweed. 2°-4° high, puberu- 

 lent : leaves petioled, tomentose beneath : umbels few : follicles erect on 

 the deflexed fruiting pedicels. — Frequent throughout in rocky woods, 

 May-June. 



3. A. incarnata L. Swamp Milkweed. 2°-5° high, nearly gla- 

 brous : leaves short petioled, smooth : umbels numerous : follicles and 

 fruiting pedicels erect. — Not uncommon in low swampy grounds through- 

 out. July-September. 



4. A. Sullivantii Engelm. 2°-5° high, glabrous : leaves oblong, 

 thick, obtuse or cordate at base, short-petioled or sessile : umbels termi- 

 nal and lateral : follicles erect on the deflexed fruiting pedicels, slightly 



