The root system is shallow but wide spreading. The greenish-yellow perfect or staminate flowers are arranged in a raceme at the end of twigs. The fruit is a fused, double-winged samara. Bigleaf maple can reproduce both sexually and vegetatively but relies primarily on sexual means of reproduction on undisturbed sites. Its reproductive strategy involves dispersing numerous seeds which germinate on the forest floor, creating a bank of persistent seedlings.
Flowers are insect pollinated.
Small mammals and birds may also disperse some seed. Germination occurs on both mineral and organic seedbeds. Predation of seed by rodents can significantly reduce germination. Young seedlings are susceptible to rodent, slug, and other invertebrate predation. Bigleaf maple seedlings are highly palatable to black-tailed deer, and intensive browsing frequently retards seedling growth.