Hemianthus micranthemoides),[2] commonly known as Nuttall's mudflower or pearlweed in aquascaping,[3][4] is an extinct species of subaquatic Micranthemum that previously inhabited wet areas from Virginia to New York.

[6] Micranthemum micranthemoides was a small subaquatic glabrous annual that exhibited creeping stems and ascending branches.

[6] Before its extinction, it was a rare occurrence in tidal mudflats[5] and in the intertidal zone of river estuaries.

When examined, these plants sold as pearlweed were actually of a similar species, Micranthemum glomeratum, which is native to Florida.

This misidentification was confirmed by Academy of Natural Sciences Botany Curator Emeritus Ernie Schuyler when the aquascaping plants were compared to herbarium specimens and descriptions of Micranthemum micranthemoides.