Pines are coniferous or evergreen trees that retain their leaves throughout the year. The pine tree does lose its old and mature needles after several years, though it is less noticeable because new needles sprout every summer and spring to push behind and replace the older ones.
Coniferous trees, such as the pine, have needle-like leaves that are less efficient in gathering sunlight but can photosynthesize all year long. The thin leaves are watertight and thick enough to survive the frost of winter, and they have a resin coat that makes them less tasty to insects. Because of these characteristics, the needles of a pine tree can stay in the tree without falling off the branches for several years.