Diurnal temperature variation in and around a Lithops lesliei plant growing in its natural habitat on a clear day

It has been suggested that the embedding into the soil of plants of the genus Lithops N.E.Br., could be an adaptation to protect the plants from supra-optimal temperatures caused by solar radiation. The temperature of a L. lesliei N.E.Br. plant growing in its natural habitat near Pretoria (Transvaal, Republic of South Africa) was determined and compared with the temperature of the surrounding soil. The plant’s temperature was always found to be very close to the soil temperature at the same depth, as was established in earlier laboratory experiments. These field results do not support a suggested substantial heat exchange between plant and soil at deeper soil levels