人厌槐叶苹 ren yan huai ye ping

Floating fronds: lamina oblong to obovate or orbicular, ca. 2.5 × 2.4-3 cm, base rounded or cordate, apex emarginate, flat or often infolded along costa, surface abaxially with sparse pale multicellular hairs, adaxially densely papillate, papillae cylindrical, ca. 1.5(-2) mm, terminated by (2-)4 setae incurved and joined at their tips; submersed frond to 12 cm. Sporocarps in long chains of up to 55, ca. 1 mm in diam., microsporangia up to 53, megasporangia 2(or 3), more densely hairy; most sporangia empty, spores if present deformed.

Still water, often forming very dense mats. Taiwan [throughout Old World tropics].

Salvinia molesta has been reported as occasionally escaping from cultivation in Taiwan. It is a very aggressive weed of hybrid origin that has been declared a noxious weed and banned from cultivation in many countries. Biological control using a weevil has been successful in some areas (R. C. Moran, Fiddlehead Forum 19: 26-28. 1992).