Maples Have Gender Identity Issues

The earliest blooming wildflower in the Maryland piedmont is skunk cabbage (Symplocarpus foetidus). The flower emerges from wet soils near or in small streams and blooms right there at ground level. It’s probably done now, but our next earliest native plant is blooming, and you have to look up to see it.

Red maple (Acer rubrum, Aceraceae) is one of the most common trees in North America, and ranges from Texas north to Minnesota and all the way to the Atlantic from Florida to Newfoundland. It’s also found in Oregon. Interestingly it’s reported as weedy by some authorities, not surprising since it’s adapted to a wide variety of growing conditions and produces a lot of seed.

While researching maples I had another “plants be complicated” moment, when tripping across a new term: polygamo-dioecious. It seems that some red maples can’t make up their minds whether they’re male, female, or both. Forgive the anthropomorphizing and let me explain.

pistillate flowers on Thalictrum dioicum (early meadow rue)

Flowers can have only pistils (the ovary-bearing or “female” reproductive parts), or only stamens (the pollen-bearing or “male” reproductive parts) or both. Flowers with pistils only are called pistillate, and those with stamens only are called staminate; either type of flower can also be referred to as imperfect. Flowers with both functional pistils and stamens are called perfect.

staminate flowers on Thalictrum dioicum (early meadow rue)

Some species bear perfect flowers only. In other species, each individual plant will bear both pistillate and staminate flowers; this condition is called monoecious, from the Greek words for one (mon) and house (oikos). And in yet other species, individual plants bear only pistillate or staminate flowers; these are plants are termed dioecious (two houses).

perfect flowers of Anemone americana (round-lobe hepatica)

Polygamo-dioecious describes species in which an individual plant bears both pistillate and perfect flowers, or both staminate and perfect flowers. Acer rubrum is one example. And in case you’re wondering (as I did), if there’s a corresponding term polygamo-monoecious, the answer is yes. In these species, an individual plant can bear all three types of flowers: pistillate, staminate, and perfect.

pistillate flowers of Acer rubrum (red maple)

Most maples are polygamo-dioecious, but a few are polygamo-monoecious.





pistil: flower part that bears ovaries (“female”)
pistillate: flower with pistils only
stamen: flower part that bears pollen (“male”)
staminate: flower with stamens only
perfect or bisexual: flower with both pistils and stamens
imperfect or unisexual: flower with only pistils or stamens
monoecious: plant that bears both pistillate and staminate flowers
dioecious: plant that bears only pistillate or staminate flowers, but not both
polygamo-monoecious: plant that bears pistillate flowers, staminate flowers, and perfect flowers.
polygamo-dioecious: plant that bears either pistillate and perfect flowers, or staminate and perfect flowers

3 thoughts on “Maples Have Gender Identity Issues

  1. Pingback: Miterwort and Dwarf Ginseng | Elizabeth's Wildflower Blog

  2. Pingback: The Botanerd’s Handy Guide to Thalictrum Species | Elizabeth's Wildflower Blog

  3. Pingback: Lucky Day | Elizabeth's Wildflower Blog

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