Chloridoid Grass Phytoliths and their Uses for Reconstructing Climates of the Past

Atlas Lee, Chiara Smythies, Rosalie Madeleine Hermans, Timothy Gallaher, Caroline Strömberg

Research output: Unpublished contribution to conferencePoster


The grass family, Poaceae, dominates over 40% of land ecosystems and is found in every biome except areas covered by ice sheets. Within Poaceae are two major clades, one being the PACMAD clade, named for the six subfamilies: Panicoideae, Arundinoideae, Chloridoideae, Micrairoideae, Aristidoideae, and Danthonoideae. The PACMAD clade is the only lineage of grasses that evolved C4 photosynthesis. This derived trait allows plants to efficiently photosynthesize under low CO2 concentrations and in hot, arid climates. Chloridoideae is the largest subfamily within the PACMAD clade with over 1,500 species across five tribes. Most Chloridoideae species use C4 photosynthesis and it is likely that some of the first transitions from C3 to C4 occurred in this subfamily; however, fossil evidence for this deep history is currently lacking. Phytoliths, which are silica bodies that form in living grass tissues and can be preserved in soils for millions of years, have great potential for filling this gap. We are studying the three-dimensional shape of phytoliths from modern Chloridoideae grasses to better recognize them in the fossil record. By linking modern Chloridoid phytolith shapes to their respective climatic conditions, we will be able to create a robust reference database to be used for future research to identify past Chloridoids and their past growing environ- ments. To do this, we are processing 3D Chloridoid phytolith models from 2D confocal microscope images to analyze and characterize the morphology, abundance, distribution, and diversity of Chloridoid phytoliths. Thus far, preliminary data suggests our findings will be especially useful in making comparisons between past and present bilobate or saddle-shaped phytoliths, though we expect to conduct further analysis on current phytolith shapes. Future studies will be able to compare our 3D modern renderings to fossil phytoliths to infer periods of climatic warming through deep time.
Original languageEnglish
Publication statusUnpublished - 2023
EventUndergrad Research Symposium (URS) - University of Washington - University of Washington, Seattle, United States
Duration: 19 May 202319 May 2023


ConferenceUndergrad Research Symposium (URS) - University of Washington
Country/TerritoryUnited States


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