One of the most conspicuous forms of vegetation in urban New Orleans is the fern that grows on walls in the Vieux Carré and on tombs in our cemeteries. The most widely used name for this species is Ladder Brake (Pteris vittatus), but it is locally known as Cemetery or Cistern Fern due to its habit of growing in these two moisture retaining areas. Ladder Brake is native to southeastern Asia and its present range in the U.S. extends from southwestern Louisiana to South Carolina and southward throughout Florida. No one knows when or how it crossed the Pacific. Some say that Ladder Brake escaped from cultivation and established itself in suitable habitat. Others have a more intriguing explanation for its arrive which accounts for its greatest abundance centering in the cemeteries. As the story goes, vases which were received from southeastern Asia were securely packaged in excelsior which was replete with Ladder Brake spores. As the vases were unwrapped and placed in cemeteries and courtyards, the spores were introduced to favorable habitat and germinated, thus beginning the life cycle of the Ladder Brake in the New World.
In New Orleans, as elsewhere, the growth of the Ladder Brake is confined to substrates rich in lime (calcium carbonate). It seems that our local soils lack an adequate amount of this necessary compound while mortar, especially the eighteenth and nineteenth century clam and oyster base variety, provides an excellent substitute.