Do Trees Have Genders?

Poet Joyce Kilmer wrote a famous poem extolling trees, but even he might have been amazed at just how miraculous some trees can be. Take the striped maple, for example. Like other flowering plants, the striped maple isn't limited to being male or female. It also can be non-reproductive or monoecious, which means growing both male and female flowers. But what's startling about this otherwise unimpressive species is that it can change its sex from one year to the next. Scientists from Rutgers and Princeton examined a large group of striped maples for four years and discovered that more than half of them changed their sex in that time. Even more striking, 26 percent changed their sex twice, and 1 percent changed sex every year. Generally speaking, younger trees were most likely to choose to be non-reproductive, while older, larger trees were more apt to be monoecious. Scientists speculate that the choices the trees make might have something to do with mortality and growth rates. For example, male maples grow faster and have lower mortality rates, so it would be logical for trees to choose to be male early in their lives.

More about maple trees:

• Although any of the 128 maple species can be used to produce syrup, the sugar maple is the most popular choice.
• Quebec, Canada, produces approximately 8 million gallons of maple syrup per year -- over nine times more than second-place Vermont.
• The oldest maple tree in Canada is the Comfort Maple, a sugar maple believed to be at least 500 years old.

Frequently Asked Questions

Do all trees have a gender?

Not all trees have genders in the way animals do. Many trees are monoecious, meaning they have both male and female reproductive parts on the same plant. However, some species, like willows and poplars, are dioecious, having distinct male and female individuals. According to botanists, about 6% of tree species are dioecious, exhibiting clear gender separation.

How can you tell if a tree is male or female?

Identifying the gender of a dioecious tree involves examining its flowers or cones. Male trees produce pollen, often resulting in flowers or cones that release it, while female trees bear structures that develop seeds or fruit after pollination. For example, female ginkgo trees produce a fruit-like structure, which is absent in males.

Does the gender of a tree affect its growth or appearance?

The gender of a tree can influence certain characteristics. For instance, male trees might produce more pollen and have more prominent flowers, while female trees may invest more energy into seed or fruit production, which can affect growth rates. In some species, like holly, the leaf shape can differ between genders, with females having more prickly leaves.

Are there any environmental benefits to having both male and female trees?

Having both male and female trees in an environment ensures genetic diversity, which is crucial for the resilience and adaptability of tree populations. Cross-pollination between genders can lead to healthier offspring and a wider range of traits, helping forests withstand diseases, pests, and climate change, as noted by forest ecologists.

Can the gender of a tree change over time?

Most trees maintain their gender throughout their lifespan. However, some species exhibit a rare phenomenon called 'gender bender,' where they can change sex in response to environmental stress or damage. This is not common and is still a subject of research to understand the underlying mechanisms and triggers for such changes.

What impact does tree gender have on urban landscaping?

Tree gender can significantly impact urban landscaping. Male trees are often preferred in cities because they do not produce messy fruits or seeds. However, this can lead to an excess of pollen, contributing to allergies. Urban planners are increasingly considering the balance of tree genders to mitigate these issues and promote biodiversity, as recommended by horticultural experts.