1. Instructions to contributors

   Announcement Pages: 1 - 1

2. Revision of Colubrina (Rhamnaceae)

   • Marshall C. Johnston

   OriginalPaper Pages: 2 - 53

3. A comparison of numerical and biosystematic studies in Haplopappus

   • R. C. Jackson
   • T. J. Crovello

   OriginalPaper Pages: 54 - 70

4. Artificial and natural hybrids in pycnanthemum (Labiatae)

   • Henrietta L. Chambers
   • Kenton L. Chambers

   OriginalPaper Pages: 71 - 88

5. The process of evolutionary migration in species of Selaginella

   • Rolla Tryon

   OriginalPaper Pages: 89 - 100