The file organization for the computerized Flora North America (FNA) data bank is described. A four level character hierarchy allows subdivision of any flora description into as many as four levels in order to specify plant character precisely. Terms at any one level will not necessarily be parallel in status. Both PLANTS and LEAVES serve as primary headings, since these are the terms by which the data base is searched or sorted. At least two levels, the first and fourth, must always be specified because a character cannot be expressed without both. The second and third are optional. Any larger hierarchy must be condensed to four levels. The actual values or character-states which describe the characters, are appended to the lowest (fourth), most specific level. A character can be described by any number of character-states which may be expressed in words or numbers. The printing of this computerized record reads like conventional language due to assigning of print and non-print codes, and the use of parallel numerical classification codes for all terms at all levels. This numericlature process is fully described. Appendices include the standard FNA form for compiling morphological data and a sample record in FNA format. (Author/MBR)