There are several similar chestnut species, such as the European sweet chestnut ("C. sativa"), Chinese chestnut ("C. mollissima"), and Japanese chestnut ("C. crenata"). The American species can be distinguished by a few morphological traits, such as leaf shape, petiole length and nut size. For example, it has larger and more widely spaced saw-teeth on the edges of its leaves, as indicated by the scientific name "dentata", Latin for "toothed". According to a 1999 study by American Society for Horticultural Science, the Ozark chinkapin, which is typically considered either a distinct species ("C. ozarkensis") or a subspecies of the Allegheny chinkapin ("C. pumila" subsp. "ozarkensis") may be ancestral to both the American chestnut and the Allegheny chinkapin. A natural hybrid of "Castanea dentata" and "Castanea pumila" has been named "Castanea" × "neglecta".