The Lumen plane has been plunged into darkness ever since. Plants need light. They need a lot of light to grow. The darkness impacted them the most and they started to die. But that's the least of the problems that the attention of a demon God brought to the plane.
The temperature of the plane began to fall in the absence of the light of the sun. Snow fell and the plane was plunged into darkness. A lot of living things died because of these changes. The cold and scarcity of food are the main causes of death. But life will survive. Life will always survive when there is ample Mana.
If given time, plants that don't need light and can survive the cold conditions will evolve and spread throughout the plane. The absence of light will cause an acceleration in plants for survival in darkness. This happened in the Lumen plane. Coniferous plants capable of withstanding the cold replaced the lush forest. It happened quickly too because of the guidance and encouragement of the tree people.
