Light as environmental regulator for germination and macrocotyledon development in Streptocarpus rexii (Gesneriaceae)

► Streptocarpus seeds require light exposure for germination. ► Post germination darkness triggers hypocotyl elongation, but inhibited macrocotyledon expansion. ► Light exposure is essential for anisocotylous growth and proper basal meristem activity. ► Blue light may be more important than red light for forming the macrocotyledon and establishment of anisocotyly.