Stratum.black
Annularia — Annularia cuspidata Lesquereux
Annularia cuspidata Lesquereux — Smithsonian Institution (NMNHPALEO), Smithsonian Open Access, CC0

Plant

Annularia

Horsetail foliage

Annularia is the whorled leaf of the giant horsetail Calamites, preserved in Mazon Creek concretions and Pennsylvanian shales worldwide as rosettes of narrow leaves around a stem. Concretions with Annularia are common and cheap and among the most attractive Mazon Creek plants. Species are separated by leaf shape and number.

PhylumTracheophyta
ClassEquisetopsida
OrderEquisetales
FamilyCalamitaceae
GroupPlant
Rank (PBDB)genus· Paleobiology Database
AuthorSternberg 1821· Paleobiology Database
Classification (PBDB)Pteridophyta › Polypodiopsida › Equisetales › NO_FAMILY_SPECIFIED· Paleobiology Database
Range (PBDB)330–247 Ma· Paleobiology Database
PBDB occurrences398· Paleobiology Database

Photographs

Annularia — Annularia sphenophylloides Lesquereux
Annularia sphenophylloides Lesquereux — Smithsonian Institution (NMNHPALEO), Smithsonian Open Access, CC0
Annularia — Cyclophora annularia (Fabricius, 1775) (NHMUK NHMUK015600823)
Cyclophora annularia (Fabricius, 1775) (NHMUK NHMUK015600823) — © The Trustees of the Natural History Museum, London, Natural History Museum (London) Data Portal, CC BY 4.0
Annularia — Cyclophora annularia (Fabricius, 1775) (NHMUK NHMUK015600822)
Cyclophora annularia (Fabricius, 1775) (NHMUK NHMUK015600822) — © The Trustees of the Natural History Museum, London, Natural History Museum (London) Data Portal, CC BY 4.0

Age

Formations

Elsewhere

Cite this article

Stratum Study. "Annularia" (Taxon). Stratum Study pack 2026.09, as of 2026-09-19. https://stratum.black/study/taxa/annularia. Accessed 2026-09-20.

BibTeX · CSL-JSON

@misc{stratum-annularia,
  title        = {Annularia},
  author       = {{Stratum Study}},
  howpublished = {\url{https://stratum.black/study/taxa/annularia}},
  year         = {2026},
  note         = {Taxon article, Stratum Study pack 2026.09, as of 2026-09-19; sources: stratum, pbdb, wikidata, smithsonian, nhm. Accessed 2026-09-20.}
}

Citations carry the pack version and the article's as-of date so they resolve to the same text later. The facts themselves belong to the sources listed below; cite those for the science.