Ferns of St. Louis

In the St. Louis Area, we have 38 not-too-obscure ferns. The PPG (Pteridophyte Phylogeny Group) now places the ferns under a big umbrella class called “POLYPODIOPSIDA”. This big class (which includes the horsetails) is divided into 4 subclasses. We’re lucky to have 3 of these subclasses here in St. Louis:

Subclass EQUISETIDAE (the Horsetails):

  • Equisetum arvense – Field Horsetail (Equisetales)
  • Equisetum laevigatum – Smooth Horsetail (Equisetales)
    (more commonly found on the Illinois side)
  • Equisetum hyemale – Tall Horsetail (Equisetales)
    (there’s also a sterile hybrid cross between E. laevigatum and E. hyemale called “Intermediate Horestail” [Equisetum x ferrissii] which makes identification challenging)

Subclass OPHIOGLOSSIDAE (the Eusporangiate Ferns):

Subclass POLYPODIIDAE (the Leptosporangiate Ferns):

These 3 ferns, although in the same Polypodiidae subclass, are in a different order:

*habitat notes kindly provided by Kathy Bildner
*distribution maps provided by BONAP