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Fossil evidence of tylosis formation in Late Devonian plants


Tyloses are swellings of parenchyma cells into adjacent water-conducting cells that develop in vascular plants as part of heartwood formation or specifically in response to embolism and pathogen infection. Here we document tyloses in Late Devonian (approximately 360 Myr ago) Callixylon wood. This discovery suggests that some of the earliest woody trees were already capable of protecting their vascular system by occluding individual conducting cells.

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Fig. 1: Late Devonian Callixylon wood containing tyloses.

Data availability

All data that support the findings of this study are included in this published article and its Supplementary Information files. A high-resolution image of the section showing tylosis from Supplementary Fig. 3 is also available on Figshare at The fossil and associated slides are currently on loan at UMR AMP Montpellier and accessible under specimen number HH5 (for HookHead No. 5). This material and other fossils illustrated in the supplementary figures will ultimately be deposited in the Trinity Geological Museum, Trinity College Dublin, Dublin, Ireland, once the study of the assemblage is completed.


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This work was supported by a Tellus-Interrvie grant (DECA, CNRS-Institut National des Sciences de l’Univers) to A.-L.D. and a PHC Ulysses grant (no. 47212TK, Irish Research Council and French Ministry of Foreign Affairs) to C.J.H. and A.-L.D. We thank C. Girard (ISEM Montpellier) and B. Meyer-Berthaud (AMAP, Montpellier) for help in the field and comments on a previous draft of the paper. AMAP (botAny and Modelling of Plant Architecture and vegetation) is a joint research unit involving Montpellier University, CNRS (UMR 5120), CIRAD (UMR51), INRAe (UMR931) and IRD (UR123).

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Authors and Affiliations



A.-L.D. and C.J.H. initiated the research project. A.-L.D., C.P. and T.D. participated in the fieldwork during which the material was collected. M.R. prepared the sections. A.-L.D. and M.R. photographed the sections. A.-L.D., C.J.H. and M.K. analysed the data with input from T.D. and C.P. C.P. analysed the sedimentological context and prepared the spores and cuticles illustrated in the supplementary figures. A.-L.D. and M.K. prepared the paper with contributions from all co-authors.

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Correspondence to Anne-Laure Decombeix.

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Nature Plants thanks Alexandru Tomescu, Zhuo Feng and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Decombeix, AL., Harper, C.J., Prestianni, C. et al. Fossil evidence of tylosis formation in Late Devonian plants. Nat. Plants 9, 695–698 (2023).

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