
“I am fascinated by the endless variation of growth forms in flowering plants and its evolutionary adaptive significance”. Starting with a plant anatomical background, I later learned how to functionally interpret anatomical observations with respect to drought stress tolerance. As an evolutionary biologist, I am eager to better understand why plants become woody during evolutionary history and why these woodiness transitions developed hundreds of times. By combining models of evolution and ecology with experimental work, I am developing a new, multidisciplinary line of research on the topic of wood evolution that will yield unprecedented insights to better understand how wild plants and crops react to drought stress in a world facing global change.
Keywords
Derived woodiness, drought stress tolerance, evolution of woodiness, hydraulic failure, insular woodiness, molecular wood pathway, wood anatomy
Evolution towards WoodinessFinding the drivers
Why have so many herbaceous lineages returned to a woody life form? Are the environmental and genetic drivers of wood formation similar or different across lineages?
I discovered that transitions from herbaceousness towards derived woodiness have happened at least 700 times independently during evolutionary history of flowering plants. This raises the intriguing question what are the environmental and genetic drivers of wood formation across all these transitions.


Currenttopics
A selection of the topics I am working on currently.

Multiple evolutionary transitions towards the woody growth form

Anatomical traits underlying drought tolerance in plants

QTL experiment with giant woody cabbage

Identification of traded timbers
Keypublications
- Dória L.C., Podadera D.S., del Arco M., Chauvin T., Smets E., Delzon S., Lens F. 2018. Insular woody daisies (Argyranthemum, Asteraceae) are more resistant to drought-induced hydraulic failure than their herbaceous relatives. Functional Ecology 32: 1467-1478.
- Lens F., Picon-Cochard C., Delmas C., Signarbieux C., Buttler A., Jansen S., Chauvin T., Chacon Dória L., del Arco M., Cochard H., Delzon S. 2016. Herbaceous angiosperms are not more vulnerable to drought-induced embolism than angiosperm trees. Plant Physiology 172: 661-667.
- Choat B., Jansen S., Brodribb T.J., Cochard H., Delzon S., Bhaskar R., Bucci S., Feild T.S., Gleason S.M., Hacke U.G., Jacobsen A.L., Lens F., Maherali H., Martinez-Vilalta J., Mayr S., Mencuccini M., Mitchell P.J., Nardini A., Pittermann J., Pratt R.B., Sperry J.S., Westoby M., Wright I.J., Zanne A. 2012. Global convergence in the vulnerability of forests to drought. Nature 491: 752-756.
- Lens F., Sperry J.S., Christman M.A., Choat B., Rabaey D., Jansen S. 2011. Testing hypotheses that link wood anatomy to cavitation resistance and hydraulic conductivity in the genus Acer. New Phytologist 190: 709-723.
- Melzer S., Lens F., Gennen J., Vanneste S., Rhode A., Beeckman T. 2008. Flowering-time genes modulate meristem determinacy and growth form in Arabidopsis. Nature Genetics 40: 1489-1492.
PhD and postdocsupervision
My team currently includes three postdocs and two PhD students, and a number of BSc and MSc students.
- Kasper Hendriks - postdoc - Exploring massive convergent evolution towards woodiness in Brassicaceae
- Alex Zizka - postdoc - Reaching for the sky: unravelling global patterns and processes to explain convergent evolution of woodiness in angiosperms
- Maximilian Larter - postdoc - Herb hydraulics: testing the role of root pressure to unravel the dynamics of drought- induced vascular dysfunction in stems
- Mehrdad Jahanbanifard - PhD - Identification of ebony woods used in music instruments based on computational phenotyping and chemical profiling
- Ajaree Thonglim - PhD - Assessing structure-function relationships in stems and leaves of Brassicaceae

Teachingactivities
- BSc: Biodiversity of Plants - Tree of Life (plant anatomy), Leiden Univ.
- BSc: MINOR Scales in Biodiversity (integrated wood anatomy), Leiden Univ.
- MSc: Development and Evolution (derived woodiness), Leiden Univ.
Studentprojects
The following projects are available to BSc and MSc students

Positive root pressure and xylem repair
Xylem anatomy of drought resistant trees

Response to drought of a giant woody cabbage cross
In themedia
- The potential implication of making crops more woody (in Dutch)
- Forests suffer from drought stress (in English)
- Compilation of global functional trait TRY database (in English)
- Woody Arabidopsis mutant (in English)
