The group including Pilea microphylla and P . trianthemoides is in need of taxonomic study. Although in the United States these two species generally can be separated without difficulty, in the West Indies they appear to intergrade. In the West Indies, P . trianthemoides is sometimes treated as P . microphylla var. trianthemoides (Swartz) Grisebach.
The name Pilea serpyllifolia (Poiret) Weddell was misapplied to this taxon by J. K. Small.