''Ptilimnium costatum'', commonly called big bishopweed, is a species of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the carrot family ( Apiaceae). It is native to the southeastern United States. It has a scattered and disjunct distribution, and is rare throughout its range. Its natural habitat in wetlands, such as swamps, marshes, and wet prairies. ''Ptilimnium costatum'' is a robust perennial, growing to 150 cm tall. It produces umbels of small white flowers. It flowers and fruits from June to October, which is generally later in the season that other ''Ptilimnium'' in its range. In addition, it can be distinguished from other nearby ''Ptilimnium'' by its longer fruit styles (1–2 mm) and perennial habit from a corm base. Populations that were previously considered ''Ptilimnium costatum'' in the West Gulf Coastal Plain of Arkansas, Louisiana, and Texas, have been treated as ''

Ptilimnium texense ''Ptilimnium'' is a group of plants in the family Apiaceae described as a genus in 1819. The common name is mock bishopweed or mock bishop's weed. It is endemic to the United States, primarily in the Southeast, the Lower Mississippi Valley, an ...

'' as of 2010. This reinstatement was based on combination of molecular, morphological, and ecological evidence.

References

{{Taxonbar, from=Q17135481 Ptilimnium Flora of North America