1. New species and new records of plants in Guiana

   • Richard S. Cowan and Collaborators

   OriginalPaper Pages: 231 - 245

2. Studies in Penstemon—IX. Notes on Northwestern American species

   • David D. Keck
   • Arthur Cronquist

   OriginalPaper Pages: 247 - 250

3. Tropical American leguminosae—III

   • Richard S. Cowan

   OriginalPaper Pages: 251 - 253

4. A revision of Hexastylis of North America

   • H. L. Blomquist

   OriginalPaper Pages: 255 - 281

5. A revision of the South American species of helianthus

   • Charles B. Heiser

   OriginalPaper Pages: 283 - 295

6. Supplementary notes on American labiatae—VI.

   • Carl Epling
   • Mildred E. Mathias

   OriginalPaper Pages: 297 - 313