Seed that either require light or dark conditions to germinate are considered photodormant. It is a form of endogenous, nondeep physiological dormancy.
Light sensitivity in seeds is a phytochrome reaction. Phytochrome is a chemically reactive pigment plants use to sense light or dark conditions (see photoperiod). Many small seeded plants require light to germinate.
They can remain dormant in the soil many years until the soil is disturbed or the canopy opens up to expose them to light for germination.
Empress tree (Paulownia) seeds require light to germinate.
