The light-induced phase-response curves of circadian leaf movements of Solanum nigrum and Lycopersicon esculentum differ from each other. The light-induced phase-response curve of the monectochimera Solanum koelreuterianum (Lycopersicon esculentum with the epidermis from Solanum nigrum) is different from that of either of the constituent species, but shows more similarities with the light-induced phase-response curve of Lycopersicon esculentum. The differences between Solanum koelreuterianum and Lycopersicon esculentum are in the quality and especially in the range of the phase-shifting.The temperature-induced phase-response curves of Solanum nigrum and Lycopersicon esculentum are similar to the light-induced ones. However, the light-and temperature-induced phase-response curves of the chimera Solanum koelreuterianum differ markedly from each other.The temperature-induced phase-response curve of the chimera Solanum koelreuterianum differs from that of Solanum nigrum, but is identical with the temperature-induced phaseresponse curve of Lycopersicon esculentum.These results offer reasons to attribute a decisive role to the epidermis in the perception of the phase-shifting light but none in the temperature influence.