Pine Tree

A pine tree is a kind of evergreen tree that grows cones and has long, thin leaves called needles. Pines belong to a group of plants called conifers, which means "cone-bearing." There are about 120 species of pine trees in the world. Most of them grow in the cooler parts of the Northern Hemisphere, in places like Canada, the United States, Europe, Russia, and the mountains of Asia.

Pines are easy to spot. Their needles grow in small bundles, usually two, three, or five needles tied together at the base. The needles stay green all year, which is why pines are called evergreens. A pine tree does drop its needles, but only a few at a time, so it never looks bare. Some pine needles can stay on the tree for five years before they fall.

Pine cones are how the tree makes new pines. A pine tree grows two kinds of cones. Small soft cones make pollen in the spring. Larger woody cones hold the seeds. When the seeds are ready, the cone slowly opens its scales and lets the seeds drop out. Some pine seeds have little wings and spin to the ground like helicopter blades.

A few pine species have an unusual trick. Their cones stay sealed shut with sticky resin and only open in the heat of a forest fire. After a fire passes through, the seeds drop onto the freshly cleared ground and start a new forest. The lodgepole pine of the western United States is famous for this.

Pines come in many sizes. The sugar pine of California can grow more than 250 feet tall, taller than a 20-story building. The smallest pines, like the Siberian dwarf pine, are short shrubs that hug the ground in cold mountain places.

Pine trees matter a lot to people. Their wood is light, strong, and easy to cut, so it is used to build houses, furniture, and paper. Pine sap is turned into rosin, which violin players rub on their bows. Pine nuts, the seeds of certain pines like the stone pine, are used in foods like pesto. In December, millions of families bring pine and fir trees indoors as Christmas trees.

Pines also live a very long time. The bristlecone pines of the White Mountains in California are the oldest known living trees on Earth. Some are nearly 5,000 years old, with twisted trunks that look more like sculpture than wood. They were already alive when the first cities were being built.