No. 1-4 and Supplement "Previous to 1956" lack volume numbering but constitute v. 1; no. 5-9 constitute v. 2.
Published by: California Botanical Society, assisted by the University of North Carolina and the National Science Foundation, 1956-1957 and supplement "Previous to 1956"; International Bureau for Plant Taxonomy and Nomenclature under the auspices of the International Organization of Plant Biosystematists by its Committee for Plant Chromosome Numbers, 1965-1974; Missouri Botanical Garden,1975/1978-2001/2003; A.R.G. Ganther Verlag K.G., 2004/2006.