206 American Midland Naturalist Monograph No. 2 



1. Leaves opposite. 



2. Leaves not evergreen ; flowers not solitary or blue. 



3. Climbing plants; corolla funnelform, yellowish; flowers fragrant 



2. Trachelospermiim 



3. Erect plants; corolla campanulate or cylindrical, pink or whitish 3. Apoc\inum 



2. Leaves evergreen; stems trailing; flowers solitary, axillary, blue ..4. Vinca 



I. Amsonia Walt. 



A. tabernaemontana Walt. Moist ground, locally throughout 111., except 

 the n. counties. May-June. [^Amsonia amsonia (L.) Britt.; Tabernaemontana 

 amsonia h.; A. salicijolia Pursh}. 



2. Trachelospermum Lem. 



T. difforme (Walt.) Gray. Moist woods and along streams, s. III., rare. 

 Union Co., Brendel. June-July. 



3. Apocynum L. — Dogbane 



L Leaves drooping or spreading, pubescent; corolla 2-3 times as long as the 

 calyx; roadsides and open woods, common. June-Sept. Spreading Dog- 

 bane A. androsae77iijoliitm L. 



L Leaves ascending; corolla only slightly longer than the calyx. 

 2. Leaves and inflorescence glabrous or nearly so. 



3. Leaves short-petioled, elliptical, acute at apex, narrowed at base; corolla 

 nearly white; roadsides, fields, open woods, common. June- Aug. [A. 



alburn Greene} Hemp Dogbane A. camiabinum L. 



3. Leaves subsessile or sessile, oval or ovate, obtuse or acutish, the lower 

 rounded, truncate, or subcordate and often clasping at base; corolla 

 greenish white; roadsides and fields, more common than the preced- 

 ing. June-Aug. [A. hypencijolmm Ait.] A. sibir'tcum Jacq. 



2. Leaves and inflorescence pubescent; roadsides and fields, common 

 throughout 111. June-Aug. Velvet Dogbane A. pubescens R. Br. 



4. Vinca L. — Periwinkle 

 V . minor L. Roadsides, woods, cemeteries; nat. from Eur. May-June. 



129. AscLEPlADACEAE Lindl. — Milkweed Family 



L Stem erect or decumbent, not twining. 

 2. Corolla-lobes reflexed. 



3. Hoods of the crown each with a small incurved horn within 1. Asclcpias 



3. Hoods without a horn; flowers greenish 2. Aceralcs 



2. Corolla-lobes erect-spreading; hoods prominently crested within 3. Asclcpiodora 



I . Stem twinmg. 



4. Corolla-lobes erect 4. Ampclanms 



4. Corolla-lobes spreading 5. Conolobus 



\. AscLEPiAS L. — Milkweed 



L Flowers orange or yellow; plants hirsute; sap watery; umbels cymose, termi- 

 nal, many-flowered; leaves lanceolate, acute, alternate or a few opposite; 

 follicles tomentulose, 7-15 cm. long, 1-1.5 cm. thick; roadsides or open 



