This close relative of minor occurs mostly from southeastern states to Central America. In Ky. it is known mostly from eutrophic ponds in the Bluegrass region. Both obscura and turionifera differ from minor as follows (FNA 22, W): fronds often reddish on the lower surface and more intensely so than on the upper surface (versus not or only slightly so and much less than on upper surface); greatest spacing between the veins near the middle of the frond or toward its tip (versus near middle or toward base). .