Pin oak, a tree that can reach 30m in height, is a monoecious tree. Its male catkins are hairy and 5-10cm, female flowers have wooly hairs and red stigmas. Its acorns are 1-2.5cm wide. The acorn cap is saucer-shaped with very small scales that are covered with tiny hairs, it covers 1/4-1/3 of the nut, which is 10-14mm wide. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.