Have you seen the sugar maples in flower? In Kentucky, they are flowering right now, but you need to look closely to see them. The flowers are not very show, their pale green blending with the green riot that is spring. These interesting flowers will reward the careful observer. Sex in maples is complicated. Even though sugar maple flowers are perfect – they have both male and female parts – most of the flowers low on the tree, as in this picture, are functionally male – the female parts don’t work. High on the tree, the opposite is true, and many flowers are functionally female. For a wind-pollinated tree like sugar maple, this division of labor may prevent pollen falling directly on the stigmas of the same flower. Maples are self-infertile, so the pollen of one tree can’t fertilize the flowers of the same tree.
We have lots of other articles about the fascinating biology of tree sex.