In spring, a single oak tree produces both male flowers (in the form of catkins) and small coon flowers (female flowers), meaning that the tress are monoecious. Oak trees have male flowers on one part of their branch, and female flowers on another part of the same branch.
Catkins are clusters, or inflorescences, of male flowers. Each of the “bumps” on the catkins is a male flower consisting of a bract (a highly modified leaf), a lobed calyx and some pollen-producing stamens. Once the stamens have released their pollen into the air, the entire catkin will fall from the tree. Maybe you’ve seen thousands of such spent catkins littering a sidewalk beneath an oak tree early in the spring. On a flowering oak twig you have to look close to see the female flowers — the future acorns.
Like many trees, oaks have irregular cycles of boom and bust. Boom times, called “mast years,” occur every 2-5 years, with smaller acorn crops in between. Boom and bust cycles of acorn production do have an evolutionary benefit for oak trees through “predator satiation.” The idea goes like this: in a mast year, predators (chipmunks, squirrels, turkeys, blue jays, deer, bear, etc.) can’t eat all the acorns, so they leave some nuts to grow into future oak trees. Years of lean acorn production keep predator populations low, so there are fewer animals to eat all the seeds in a mast year. Ultimately, a higher proportion of nuts overall escape the jaws of hungry animals.
Oak trees take decades to mature and one oak produces more than 2,000 acorns every year, but only one in 10,000 acorns will manage to develop into oak tree. Most oaks are at their acorn production peak at 50 to 80 years of age. After the oak reaches 80, acorn production generally begins to decrease. The usual lifespan of an oak is about 200 years, but some live over a 1,000 years.
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[…] of the leaves, there are 3-6 unequal “thumb” shaped lobes, which give them a wavy appearance. Male oak trees flower with violet-colored catkins on spiked stems, whereas female oak trees flower with pale green […]