Answer
The plant from the warmer site (warm soil, hot spring) would have proportionally more saturated lipids than the plant from the cooler soil.
Work Step by Step
This is because lipid saturation is tuned to the temperature at which an organism normally lives. Organisms from hot climates or which set their own body temperature have more saturated lipids in their membranes to maintain membrane stability while those from cooler habitats have more unsaturated lipids to maintain membrane fluidity.