Features: The noble oak is generally acclaimed as the national tree of the United States. Tall, stately, and sheltering, oaks can live for centuries. As they are an indispensable source of food and cover for many insects, animals, and birds, planting them invites a diversity of wildlife to your yard. Oak wood is strong and stands up to stormy weather. Thick, leathery leaves filter summer sunlight, making oaks effective shade trees, as well. An old adage says that you plant an oak for your children, but that doesn't mean you will have to wait years to enjoy an oak. The chinkapin oak, for example, can grow as much as 20 feet in 10 years.
Choices: The United States and Canada claim nearly 100 native oak species, a diverse group that ranges from low shrubs to forest giants. There's one for nearly any condition. The willow oak thrives in wet soils, while the black oak likes it very dry. The silverleaf oak takes unbelievable desert heat; the bur oak readily shakes off the cold from Saskatchewan to Quebec. The live oak is evergreen; the swamp chestnut oak has great fall color.
Features: The hawthorns are some of the toughest little trees in the tree business. Native hawthorns have white or pale yellow flowers in spring, some (Washington hawthorn, in particular) have vivid red color in fall, and almost all get to be only about 30 feet in height. The sweeping branches of the cockspur hawthorn are revealed once winter arrives, and the bright fruits of the green hawthorn make a splendid display until they finally drop or are taken by birds.
Uses: Most species have thorns, so take care to place them where you won't run into them. The thorns, on the other hand, make them desirable habitat for the nesting birds that add so much pleasure to gardening. Hawthorns are in the rose family, along with crabapples, a closely related species to which they bear a resemblance. Hawthorn fruits are edible and taste much like crabapples. Some, such as mayhaw fruits, are made into jelly or wine.
Features: The scent of pine stands for purity and freshness, or so you'd think from looking at the labels of cleansers and air fresheners. But there's more to appreciate about pine trees than that lab-created imitation aroma. They'll grow in the poorest possible soil, which means you're sure to find one that will take to your land, be it dense clay or porous sand. Most pines are unimpeded by drought; loblolly pine, among others, tolerates wet soil as well. Frequent partners to oaks in the wild, pines have adapted to the coldest and hottest of climates.
Choices: You'll have no trouble finding a pine that suits your garden's size, either. Ponderosa pine and eastern white pine, for instance, reach regal heights, growing up to 100 feet tall, where their aromatic needles sing in the wind. Don't have space for a skyscraping tree? Shore pine and piñon pine top out at a more manageable 20 to 30 feet.