The Index to Plant Chromosome Numbers is a continuation of the series begun in 1956 by Marion S. Cave and colleagues at the University of California, Berkeley. The last issue, Volume 81 of Monographs in Systematic Botany from the Missouri Botanical Garden, was published in 2000 and covered the years 1996 to 1997. The IPCN project has been housed at the Missouri Botanical Garden, St. Louis, since 1978 and is supported in part by the United States National Science Foundation. Indexes prior to 1975 were published in Regnum Vegetabile (see the Bibliography of Previous Indexes to Plant Chromosome Numbers, below, for a complete listing). Format and the arrangement of major groups are for the most part identical to those in the last Index. Standardized family names ending in -aceae are used throughout; the more traditional names, such as Compositae, Labiatae, Palmae, being replaced by their alternates, Asteraceae, Lamiaceae, Arecaceae, etc. Genera are assigned to families according to K. W. Dalla Torre & H. A. T. Harms, Genera Siphonogamarum (1900–1907), except that the conifers are arranged according to the classification of W. Dallimore & A. B. Jackson, revised by S. G. Harrison, in A Handbook of Coniferae and Ginkgoaceae (1966). Pteridophyte genera are assigned to families following the system by R. C. Moran in Flora Mesoamericana, Volume 1 (1995). Fungi and algae mostly follow the system in Englers Syllabus der Pflanzenfamilien (1954) and Index Nominum Genericorum (Plantarum) (1979–1986), respectively. The genera of mosses have been arranged following M. R. Crosby & R. E. Magill, A Dictionary of Mosses (1981). Liverworts are arranged according to an unpublished system prepared by J. J. Engel.

During the assembly of the Index, the published information has been altered as little as possible, but owing to space limitations, data in the columns for gametic (n) or sporophytic (2n) counts have sometimes had to be shortened, and then most often "etc." has been added to indicate that the original report contained more data. Meiotic and gametophytic counts, whether including chromosome configurations or not, are placed in the gametic column, following the convention established from the initiation of IPCN. Generic names have been adjusted to exclude orthographic variants. Author citations have also largely been brought to conformity with abbreviations suggested by R. K. Brummitt & C. E. Powell, Authors of Plant Names (1992).