Telmatoblechnum serrulatum, the toothed midsorus fern, is a species of fern in the family Blechnaceae, native to Florida, southeastern Mexico, Central America, the Caribbean, northern and western South America, Brazil, Paraguay, and northeastern Argentina.

[2] The species is commonly found in freshwater marsh and swamp conditions in tropical or subtropical locations.

[4] The range for this fern species is from Florida to South America and has been recorded in Malaysia and Australia.

[3] It has shown good resistance to lead contamination when growing on coal mine tailings.

[3] The rhizomes form horizontally, even sometimes climbing tree trunks, and are covered in dark brown scales.