How Are Broadleaf Trees Different From Conifers?

Tree Orders

• Broadleaf trees, conifers and palms compose the natural orders of trees. Broadleaf trees are mostly deciduous, losing their leaves in the fall. Also called hardwoods, some broadleaf trees actually have soft wood, such as willows (Salix), with varieties that grow in USDA zones 3 through 8. Conifers are sometimes called softwood trees and are usually evergreens, with some exceptions, such as bald cypress (Taxodium distichum), which grows in USDA zones 4 through 9 and loses its needles in the fall.

Leaves

• The appearance of leaves on conifers and hardwood trees is obvious -- needles vs. flat leaves. Because most broadleaf trees are deciduous and need their leaves to last just one season, they are less apt to produce chemicals, like conifers do, that deter insects. As a result, broadleaf trees provide habitat for insects, food for birds when the leaves are on the tree, and food for ground insects once the leaves fall and decay.

Bark

• Just as the leaves on broadleaf trees provides more habitat for insects and birds, so, too, does the bark. Broadleaf trees have thinner bark than do conifers, allowing insects and fungi to infect the trees through wounds in the thin bark. With more insect and fungal decay, broadleaf trees decay sooner than conifers. Conifers, on the other hand, have thick bark that resists cuts and bruises and also produces resins that combat fungi.

Habitat and Growth

• You'll rarely see broadleaf trees at very high elevations in the mountains, because they need soil that is deep and rich. Broadleaf trees grow more often in canyons, where the soil is better and where there is more moisture. Conifers prefer higher and dryer mountain slopes. Both types of trees produce seeds, with conifers' seeds contained in distinctive cones that are large, small, round or oval.

Shape, Size and Age

• Many broadleaf trees are shade trees, with wide, expansive shapes. Conifers typically grow in more upright shapes, making them taller and less wide than broadleaf trees. Conifers generally live longer than broadleaf trees, which die sooner due to fungal disease. The oldest-known tree species, close to 5,000 years old, is the conifer bristlecone pine (Pinus aristata), which grows in USDA zones 4 through 8; and the largest tree species is the conifer giant sequoia (Sequoiadendron giganteum), which grows in USDA zones 6 through 8. Olive trees (Olea europaea), which grow in USDA zones 8 through 10, are among the oldest broadleaf trees, with one in Jerusalem dated as 900 years old.