Tyloses in fossil plants: New data from a Mississippian tree, with a review of previous records

Tyloses are protoplasmic swellings of parenchyma cells into the lumen adjacent conducting cells. They develop as part heartwood formation process, or in response to embolism pathogen infection. Here, we report oldest fossil evidence date tylosis that occurs permineralized wood (pro)gymnosperm Dameria hueberi from Tournaisian (lower Mississippian, ca. 350 Ma) Australia. Different developmental stages recognizable range small bubble-like protrusions dense tyloses entirely filling The trigger for development D. remains unknown. A survey record shows their occurrence most groups vascular plants since Carboniferous. Future research this field will screen even older (Devonian) fossils and aim understand roles these structures have had plant–pathogen interactions plant hydraulic properties past.