Icacinicarya platycarpa

Icacinicarya platycarpa

Reid et Chandler

Fossil group Plants
Order Icacinales
Family Icacinaceae
Genus Icacinicarya
Taxonomic status Accepted
Geological age Ypresian

Summary

Icacinicarya platycarpa was an early Eocene icacinaceous plant whose fruit contained an elongate, strongly flattened stone protecting a single seed. The hard endocarp carried a network of ridges, while its inner seed cavity had a smooth rather than papillate lining.

Most London Clay examples are locule casts rather than intact fruit stones, so the preserved pattern may be an impression of the inside of the wall rather than the original outer surface. The fruit shows the general construction of Icacinaceae, but no attached vegetative organs reveal whether the parent plant was a tree, shrub or climber.

Quick Identification

Look for: an elongate oval, very flat/lenticular stone or locule cast with a distinct network of ridges. Most specimens are casts, so confirm whether the visible reticulum represents the inner wall impression rather than preserved outer endocarp.

Diagnostic Features

  • Fruit stone is elongate oval in side view and strongly flattened-lenticular in cross-section.
  • A clear reticulum of ridges forms the principal surface pattern.
  • The same reticulate pattern is commonly expressed on locule casts when the endocarp wall is absent.
  • Locule lining is non-papillate.
  • Typical material spans a broad size range, from about 16 to 26 mm long.

Fossil Details

Typical size
About 16–26 mm long, 11.5–21 mm wide and up to roughly 10 mm thick.
Fossil material
Seed, Fruit
Preservation
Intact endocarps are uncommon; most surviving material is a locule cast. Crushing can further exaggerate the naturally compressed profile, and abrasion can weaken the ridge network. Species-level identification is strongest where the full outline and reticulum are both visible.

Similar Species

Recorded Fossil Sites

References

  • Eleanor Mary Reid; Marjorie Elizabeth Jane Chandler. (1933). The London Clay Flora. . British Museum (Natural History), London View reference
  • Gregory W. Stull; Neil F. Adams; Steven R. Manchester; Dan Sykes; Margaret E. Collinson. (2016). Revision of Icacinaceae from the Early Eocene London Clay flora based on X-ray micro-CT. Botany, 94(9), 713–745 View reference
  • Kathleen B. Pigg; Steven R. Manchester; Melanie L. DeVore. (2008). Fruits of Icacinaceae (Tribe Iodeae) from the Late Paleocene of western North America. American Journal of Botany, 95(7), 824–832 View reference
  • Margaret E. Collinson; Neil F. Adams; Steven R. Manchester; Gregory W. Stull; Fabiany Herrera; Selena Y. Smith; Mary J. Andrew; Paul Kenrick; Dan Sykes. (2016). X-ray micro-computed tomography (micro-CT) of pyrite-permineralized fruits and seeds from the London Clay Formation (Ypresian) conserved in silicone oil: a critical evaluation. Botany, 94(9), 697–711 View reference
Last Reviewed
26 August 2026 Reviewed by Sam Harris