The archetypal oak grows large and spreads wide, with muscular, near-horizontal lower branches that seem to defy gravity. But the group’s 500 species, all native to the Northern Hemisphere, also include upright, pyramidal, and shrubby oaks; in fact, “chaparral” comes from chaparra—Spanish for a dwarf evergreen shrub oak. Oak leaves can be deciduous or evergreen (the latter are called live oaks); lobed, toothed, or smooth edged; but they’re always arranged in an alternate pattern along stems. Some have terrific fall color. All oaks produce inconspicuous flowers followed by acorns, whose single nuts have cuplike caps covered with closely set scales. Some kinds of acorns are edible and sweet, while others are bitter and unpalatable.
Oaks come in two broad categories: white oaks have acorns that mature during the season in which they are produced, and often have leaves with rounded lobes; red and black oaks have acorns that take two seasons to mature, and often have leaves with pointed lobes. Each group can hybridize only within itself.Quercus phellos
This deciduous tree grows to 50–90 ft. tall and 30–50 ft. wide. Pyramidal in youth, it spreads wider with age. Smooth gray bark. Leaves look more like those of willow (Salix) than those of a typical oak—2 1/2–5 in. long and 1/3–1 in. wide, smooth edged. Foliage turns yellowish before falling; in warmer regions, dead leaves may hang on through winter. Has the most delicate foliage pattern of all the oaks. Spherical, 1/2-in.-wide acorns have a shallow cap enclosing only the end of the nut.
Discovered in an Atlanta, Georgia, garden, this is an heirloom hybrid between Verbena canadensis
Only 1 in. tall, spreading to 3 ft. The cylindrical leaves turn red in fall and winter, green up again...
Growing to 2–3 ft. tall and wide, with aromatic, ferny-looking blue-green leaves, this native of...