1. Theoretical evolutionary rates in plant groups and the fossil record

   • Karl J. Niklas

   OriginalPaper Pages: 241 - 254

2. New genera and species of ericaceae (Vaccinieae) from Costa Rica and Panama

   • James L. Luteyn
   • Robert L. Wilbur

   OriginalPaper Pages: 255 - 276

3. Monographic studies in cassia (Leguminosae: Caesalpinioideae). IV. supplementary notes on section apoucouita Bentham

   • Howard S. Irwin
   • Rupert C. Barneby

   OriginalPaper Pages: 277 - 290

4. A study of morphological variability in chenopodium incanum (Chenopodiaceae) and the recognition of two new varieties

   • Daniel J. Crawford

   OriginalPaper Pages: 291 - 296

5. Chromosome races of gaillardia pulchella (Asteraceae)

   • Warren Stoutamire

   OriginalPaper Pages: 297 - 309

6. The occurrence of nitro-toxins in North American astragalus (Fabaceae)

   • M. Coburn Williams
   • Rupert C. Barneby

   OriginalPaper Pages: 310 - 326

7. The occurrence of nitrotoxins in Old World and South American astragalus (Fabaceae)

   • M. Coburn Williams
   • Rupert C. Barneby

   OriginalPaper Pages: 327 - 331

8. Rocky Mountain Flora

   • Arthur Cronquist

   Book review Pages: 331 - 331

9. Two early mississippian seeds from the price formation of Southwestern Virginia

   • Patricia G. Gensel
   • Judith E. Skog

   OriginalPaper Pages: 332 - 351

10. Manual of the Vascular Plants of Wyoming

    • R. C. Barneby

    Book review Pages: 352 - 352