A taxonomical examination of Trapa japonica and T. bispinosa based on nut characters

We examined the sixteen quantitative characters of Trapa and conducted principal component analysis for T. japonica Flerow and T. bispinosa Roxb. in South Korea. Trapa bispinosa has been recorded as 'Ma-reum (T. japonica Flerow)' in the Korean flora, but this taxon is distinct from T. japonica in terms of width, thickness and upper horns of its nuts. Principal component analysis (PCA) confirms the morphologically distinct status for the two species. We suggest the common name 'Keun-ma-reum' for Trapa bispinosa to the Korean flora.