A data matrix was compiled to accommodate the variation in 35 easily observable characters recorded comparatively from about 650 herbarium specimens of 26 species representing the eight genera of the Polygonaceae in the flora of Egypt. Only the characters with relatively sufficient constancy in all specimens of the same species were selected to warrant their use in the discrimination between the taxa. The DELTA key-generating package of computer programs was used to construct a conventional key to all genera and species. Only 14 of the recorded characters were sufficient for key construction. An unedited version of the detailed description of every species in terms of the entire set of 35 characters is provided; surplus characters aid in confirming its identification. Item descriptions, along with the list of characteristics, can be used to re-synthesize the original data matrix, which can then be adjusted to include more characters and/or taxa. The key and descriptions have several advantages over their manually constructed predecessors.