From Citizendium, the Citizens' Compendium
Pine (tree) : A tree which is coniferous and belongs to the genus Pinus and the family Pinaceae. There are over 100 different species of pine tree, and are found in numerous locations worldwide. Its bark is usually thick and scaly, and it often has needles instead of leaves, and consist of four types: seed leaves, juvenile leaves, scale leaves, and needles. They're coniferous meaning the seeds are inside cones.