 Collom believed that some plants from higher altitudes could adapt themselves to lower altitudes if they were planted and cared for at an intermediate altitude and had time to adjust to the changed conditions.She was encouraged in this theory of progressive adaptation by Dr J. J. Thornberry, a botanist at the University of Arizona, and Dr F. J. Crider, Director of the Boyce Thompson Arboretum.She put this theory into practice by collecting plants from higher altitudes and then planting them in her garden.