The sporophyte-less filmy fern of eastern North America Trichomanes intricatum (Hymenophyllaceae) has the chloroplast genome of an Asian species.

Trichomanes intricatum, the sporophyte-less filmy fern of the eastern United States, has been considered to be a species whose sporophyte generation has become extinct or is possibly still present among the many species of Trichomanes s.l. in the new world tropics but unable to grow in a temperate climate. A close relationship to Asian species has heretofore not been considered. Comparison of rbcL and rps4-trnS sequences to species of Trichomanes s.l. reveals that T. intricatum shares its chloroplast genome with Crepidomanes schmidtianum of eastern Asia. Because C. schmidtianum is a sterile triploid and the ploidy level of T. intricatum is unknown, several scenarios leading to their sharing of these maternally inherited genes must be explored.