Phytoliths, morphometrics, and cakes: Finishing my PhD
Hi everyone! I’m Rosalie, and if you saw me at the last International Meeting in Phytolith Research (IMPR) in Barcelona, you might remember me as the person who could not stop talking about phytolith morphometrics. I’m excited to share that I officially defended my PhD!
How it started
Coming from an archaeology background, I began my PhD working on phytoliths and the medieval period in Europe. Along the way, this led to:
- Studying dicotyledon phytoliths in modern plants commonly found at European archaeological sites.
- Conducting morphometric analyses on Elongate dendritic phytoliths to improve the identification of cereals in archaeological records.
My interest in morphometrics brought me to the University of Washington, which I first visited in 2022 to work in Prof. Caroline Strömberg’s lab. Together with Dr. Timothy Gallaher, Caroline published the first 3D phytolith study in 2020 (on Grass Silica Short Cell Phytoliths, GSSCP). I was fortunate to become involved in ongoing projects exploring the evolution of palms and grasses over millions of years, studies that eventually became part of my own PhD research as well.
The big day: becoming Dr. Hermans
On February 24th, 2026, I defended my dissertation, “Typological and morphometric analyses of phytoliths in modern plants: Developing tools for archaeological and palaeoecological research,” under the supervision of Prof. Christophe Snoeck.
I was honored to have a fantastic jury, including Dr. Welmoed Out, who is also part of the Committee for Phytolith Morphometrics and traveled all the way from the Netherlands to attend in person.
To celebrate the occasion, I combined my PhD defense with another passion of mine: baking. My family and I made all the sweet and savory cakes for the reception ourselves. There was something very special about celebrating the end of the PhD journey surrounded by colleagues, friends, family, and plenty of homemade treats.
What’s next? (Spoiler: more morphometrics)
After spending so much time writing (boy oh boy!), I am very happy to be back in the lab! I recently started a postdoc in the Strömberg lab at the University of Washington, where we are continuing and expanding the 3D phytolith work started by Caroline and Tim.
This year, we are:
- Finalizing a modern dataset of more than 7,000 3D phytolith models spanning all grass subfamilies.
- Using this extensive reference collection to identify fossil phytoliths from sites around the world, including samples from India dating back 67 million years.
- Exploring grass evolution like never seen before!
Curious to read more? You can find my full thesis here: https://researchportal.vub.be/en/publications/typological-and-morphometric-analyses-of-phytoliths-in-modern-pla/
A big thank you to everyone in the International Phytolith Society for the support, encouragement, and inspiration throughout the years. Looking forward to seeing many of you again soon (maybe at the next conference!)
References
Brightly, W., Crifò, C., Gallaher, T., Hermans, R., Lavin, S., Lowe, A., Smythies, C., Stiles, E., Wilson Deibel, P. and Strömberg, C., 2024. Palms of the past: can morphometric phytolith analysis inform deep time evolution and palaeoecology of Arecaceae?. Annals of Botany, 134(2), pp.263-282.
Hermans, R., Strömberg, C.A., Löffelmann, T., Vrydaghs, L., Speleers, L., Chevalier, A., Nys, K. and Snoeck, C., 2025. Phytoliths in dicotyledons occurring in Northwest Europe: establishing a baseline. Annals of Botany, 135(5), pp.885-908.
Hermans, R., Li, M., Brightly, W.H., Gallaher, T.J., Smagghe, W., Lee, H., Arco, L., Stas, L., Savieri, P., Vrydaghs, L. and Nys, K., 2025. Elongate dendritic phytoliths as indicators for cereal identification and domestication: exploring a 3D morphometric approach. Frontiers in Plant Science, 16, p.1643447.
Hermans, R. Gallaher, T., Brightly, W., Zender, C., Snoeck, C., Strömberg, C. (accepted with revisions) Reconstructing Cenozoic grasslands in North America and western Eurasia: Evidence for cold-season grasses from 3D phytolith morphology, New Phytologist.
Gallaher, T.J., Akbar, S.Z., Klahs, P.C., Marvet, C.R., Senske, A.M., Clark, L.G. and Strömberg, C.A., 2020. 3D shape analysis of grass silica short cell phytoliths: a new method for fossil classification and analysis of shape evolution. New Phytologist, 228(1), pp.376-392.