The leaves are 7–15 cm (3–6 in) long and 5–13 cm (2–5 in) broad, variable in shape, with a lobed margin. Most often, the basal 60% is narrower and deeply lobed, while the apical 40% is wider and has shallow lobes or large teeth. The flowers are greenish-yellow catkins, produced in the spring. The acorns are very large, 2–5 cm (0.8–2 in) long and 2–4 cm (0.8-1.5 in) broad, having a large cup that wraps much of the way around the nut, with large overlapping scales and often a fringe at the edge of the cup.–Wikipedia
Bur oaks bear seed up to an age of 400 years, older than reported for any other American oak. The minimum seed-bearing age is about 35 years, and the optimum is 75 to 150 years (5,16). Silvics Manual Volume 2. Hardwoods. USDA
defying expectations.
