One of the most recognizable symbols of fall is a branch of oak leaves and a couple of acorns. Oak trees (Quercus spp.) have been around for approximately 55 million years old, with the oldest North American specimen being 44 million years old. Long before pumpkins and corn stalks came to symbolize harvest and bounty, people depended on the humble acorn and majestic oak tree for sustenance and shelter. Today we think of oak trees in terms of shade, firewood, and sturdy furniture, but as acorns can be stored for long periods of time and the flour made from them is quite nutritious for thousands of years acorns were the main food staple for people in balanocultures.
Oak trees are a dominant plant in many forest ecosystems and currently there are about 500 species of oaks growing in temperate and tropical climates throughout the world. There are about 90 species of oak trees native to the United States including eleven here in New York.
All oak trees produce acorns, this is the fruit and contains a nutrient rich seed. It can be hard to imagine that a single acorn can become a 200-year-old tree cable of producing millions of other acorns. Acorn production does not begin until an oak tree is about 20 years old, with peak production when the tree is between 50 to 80 years old. After that acorn production tapers off, although some trees will produce acorns well into their second century and beyond.
Oaks in North American are divided into two groups: White Oaks and Red (Black) Oaks. Each group has distinct leaf shape and acorn production strategy. White or annual oaks have rounded-lobed leaves, flower later in the spring than red oaks, and have sweet tasting acorns that mature in one season. The acorns of the white oaks can start to germinate as soon as they hit the ground in the fall.
Northern red oak leaves
Red or biennial oaks have pointed-lobed leaves, flower earlier in the spring than white oaks, and have bitter tasting acorns that take two years to mature. Because their acorns take two years to mature, it is possible to have two seasons of acorns on each twig. The acorns of the red oaks need a period of cold stratification that lasts 6-8 weeks in order to germinate.