Two further species were later described by the Japanese botanist Gen-ichi Koidzumi, Phryma oblongifolia and Phryma nana. However, these species were generally not accepted, and populations in Asia and North America were usually treated as the single species Phryma leptostachya, being distinguished only at the rank of subspecies and variety.
In addition to two other species described by Japanese botanist Gen-ichi Koidzumi, Phryma oblongifolia and Phryma nana were later identified. Nevertheless, these species were not widely accepted, and populations in Asia and North America were typically regarded as the single species Phryma leptostachya, distinguished only at lower taxonomic ranks.