Importance of Endosperm for Nutrition ofFraxinus pennsylvanicaSeedlings

Contact between endosperm and cotyledons of germinating Fraxinus pennsylvanica Marsh. seedlings was not essential for continuation of seedling growth or adaptation of cotyledons for photosynthesis. However, when cotyledons were in contact with endosperm, the cotyledons had faster rates of elongation and dry weight increase, slower depletion of reserves, and higher chlorophyll contents. Photosynthetic contributions by cotyledons may be enhanced if environ mental conditions support rapid emergence of cotyledons from surrounding seed structures.