TONQUA BEAN. The Tonqua, Tonka or Tonquin bean, also called the coumara nut, is the seed of Dipterix odorata, a leguminous tree growing to a height of 8o ft., native of tropical South America. The drupe-like pod contains a single seed possessed of a fine sweet " new-mown hay " odour, due to the presence of coumarin (q.v.). Tonqua beans are used principally for scenting snuff and as an ingredient in perfume sachets and in perfumers' " bouquets."