How big does a tree have to be before it can be called a big tree? If the question sounds like something you might have pondered in Philosophy 101, so does the answer: "It's all relative."

In New Hampshire, an official "big tree" is the largest specimen of any species within a given county. The state's Big Tree Program is cosponsored by the Society for the Protection of New Hampshire Forests, the New Hampshire Division of Forests and Lands, and UNH Cooperative Extension. The forest society maintains the registry of big trees and selects the state champion for each species.

Some big trees are truly giants; others aren't very big at all. One of the state's smallest big trees is located on the university campus near Putnam Hall. The largest known witch hazel in New Hampshire, it stands only 14 feet high and measures 12 inches in circumference at breast height (4.5 feet above the ground).

That witch hazel is one of four state champion trees growing on the UNH campus. Another state champion, a 37-foot-high Kentucky coffee tree, shades the approach to Thompson Hall. In fall, its leathery brown pods hang down like streamers and are filled with hard-shelled seeds that the early settlers used to make coffee. Just a few steps away is the state's largest overcup oak, 76 feet high and 90 inches in diameter, on the island in the T-Hall parking lot. A scarlet oak, 68 feet high and 91 inches in diameter, grows next to the sidewalk at the foot of the driveway to the Memorial Union Building.

Several other state champion trees can be found on private property in Durham, including a Douglas fir (72 feet high and 66 inches in diameter) and an Austrian pine (44 feet high and 48 inches in diameter). The town used to claim the country's largest Norway spruce, but it lost its status when it was damaged by hurricane winds in 1985.

Durham's most famous big tree, the Paul Bunyan pine in College Woods, isn't among the contenders for the title in its species. With a height of 135 feet and a circumference of 152 inches, it can't match the state champion white pine, which is located in Sanbornton and stands 134 feet high with a circumference of 204 inches.