These seed pods, cones, flowers and fruit are major markers that help in keying out and identifying a specific species of tree. Not as dependable as a leaf, a fruit or seed pod might only be found at certain times of the year. Leaves generally hang around either on the tree or on the ground beneath the tree.
Reproductive structures are great sources for tree identification. The acorn of an oak is a seed but completely different from a maple's samara. Study the illustration to familiarize yourself with many of the possible seeds and fruiting structures on trees.