Limnobiophyllum scutatum

Overview

Picture small clusters of leaves floating on water. Limnobiophyllum scutatum was an aquatic plant living in Paleocene lakes. Leaves, stems, and roots preserved together reveal the life of an ancient water plant.^[1]

Key facts

Small leaf clusters were connected by horizontally spreading stems called stolons. This connection might have been missed if only isolated leaves were known. Following the radiating veins and connecting stems allows the fossil to be read as a whole plant.^[1]

Time and place

Important research specimens came from Joffre Bridge in Alberta, Canada. Plant traces remained in clay deposited in an ancient lake within the middle Paleocene Paskapoo Formation. They open a window onto freshwater landscapes after the dinosaur mass extinction.^[1]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

Egg-shaped or kidney-shaped leaves gathered around a short stem to form small rosettes. Roots grew beneath the rosettes, while stems extended sideways to connect with other leaf clusters. Its appeal lies in small structures spreading over water rather than in the form of a large tree.^[1]

The original diagnosis gives the first leaf’s diameter as usually 15–20 mm, with a maximum of 40 mm.^[1]

Habitat and reproduction

Researchers interpreted it as a floating flowering plant. Leaf clusters, stolons, and roots preserved together make it possible to consider how it spread across the water surface. Stolons were important growth structures connecting several leaf clusters.^[1]

Fossil discovery

A 1997 study examined more than 200 specimens. It went beyond naming a plant from a single leaf to reconstruct the whole plant by comparing organs preserved in attachment.^[1]

References

1. Stockey, R. A., Hoffman, G. L. & Rothwell, G. W. (1997). “The fossil monocot Limnobiophyllum scutatum: Resolving the Phylogeny of Lemnaceae.” American Journal of Botany, 84(3), 355–368. https://doi.org/10.2307/2446009
2. Stockey, Hoffman & Rothwell (1997), The fossil monocot Limnobiophyllum scutatum: resolving the phylogeny of Lemnaceae
3. Stockey, Rothwell & Johnson2007 — Connected aquatic plant fossils of Cobbania

Research questions

Its relationships with other aquatic plants, including living duckweeds, were an important research topic. Similar aquatic lifestyles can produce similar forms, so comparisons of several organs rather than leaves alone help reveal evolutionary branches.^[1]

Observation

Look at leaf clusters, roots, and sideways connecting stems together rather than at a single leaf.^[1]