Calcium oxalate crystals have been identified in the majority of flowering plants, including soybean. The relationship between calcium oxalate and soluble oxalate is not known. A search for natural or induced variation in crystal numbers and patterns included mutagenized seedlings of a soybean line, transposon-tagged plants, plant introductions (accessions) of the cultivated, wild annual and wild perennial soybean, and accessions of related taxa to Glycine. Leaf samples (circular leaf punches) were taken from herbarium specimens and greenhouse and field-grown plants. The samples were chemically cleared, mounted on slides and viewed with a compound light microscope between crossed polarizers. The number and arrangement of leaf prismatic crystals (calcium oxalate, monohydrate) in an individual plant were similar but varied among accessions and species. The crystals were typically associated with the veins and lamina. The utility of leaf crystals as an aid in classification of these taxa will be presented. No accessions devoid of calcium oxalate crystals were found even though one taxon from Japan had the smallest and fewest numbers of crystals of any specimen observed.

Key words: calcium oxalate, crystal patterns, Glycine, related taxa