Because the cytoplasm of a plant normally degrades after the death of the plant, finding cytoplasm in a plant body after a prolonged period of time, especially in fossil plants, is unexpected. Recent work on several 100-Myr-old plant fossils from Kansas, USA indicates, however, that cells and their contents can be preserved. Most of the cells in these fossil plants appear to be in a state of plasmolysis, and these fossil cells bear a strong resemblance to laboratory-baked cells of extant plant tissues. Based on a comparison with extant material plus biophysical and biochemical analyses of the cytoplasm degrading process, a new hypothesis for cytoplasm preservation in nature is proposed: high temperature, a concomitant of commonly seen wildfires, may preserve cytoplasm in fossil plants. This hypothesis implies that fossilized cytoplasm should be rather common and an appropriate substance for research, unlike previously thought. Research on fossil cytoplasm closely integrates paleobotany with biochemistry, biophysics, as well as fire ecology, and invites inputs from these fields to paleobotany to interpret these provocative findings.