For aromatic foliage and white or light green bark, plant a blue-gray eucalyptus (Eucalyptus caesia). An Australian native, this eucalyptus grows to 20 feet tall and is hardy in U.S. Department of Agriculture plant hardiness zones 7 through 10. It grows in a variety of site conditions, including wet to dry soil. As its name suggests, the snow gum (Eucalyptus pauciflora subsp. niphophila) has both white bark and silver-gray foliage. This 25-foot-tall tree has a low, spreading canopy and blooms with white summer flowers. It's hardy in USDA zones 8 through 10 and grows well in wet or dry sites with acidic or alkaline soil.
The Korean fir (Abies koreana) has white bark, sometimes with hints of purple or green. This 35-foot-tall conifer is hardy in USDA zones 5 through 6 and grows best in moist, acidic soil. Korean firs produce large, purple-brown cones in winter. An Australian native, the Sydney red gum (Angophora costata) grows to 50 feet tall and has white or pink bark that may be exfoliating or smooth. This broadleaved evergreen blooms with showy white blossoms in summer and has striking, spreading branches. It's hardy in USDA zones 9 through 10 and prefers sunny sites with alkaline soil.
The 65-foot-tall ghost gum (Corymbia papuana) has white, smooth bark. Native to Australia and Papua New Guinea, this spreading evergreen has gray-green foliage and blooms in summer with white flowers. It's hardy in USDA zones 7 through 10 and grows well in sunny or partially shaded sites with alkaline soil. The white box (Eucalyptus albens) also reaches heights of 65 feet. This fast-growing tree has aromatic, gray-green leaves that contrast with its white or light gray bark. White box trees are hardy in USDA zones 7 through 10 and prefer full sun exposures.
The alpine fir (Abies lasiocarpa) is native to the Pacific Northwest, from Oregon to Alaska. This conifer grows to 90 feet tall with a narrow, 20-foot spread. Its aromatic, white or light-gray to red-brown bark is offset by its blue-green needles. The alpine fir is hardy in USDA zones 5 through 6 and requires moist to wet soil. For large spaces, plant a lemon-scented gum (Corymbia citriodora). This evergreen grows to 160 feet tall with a canopy that spreads up to 100 feet. Its bark may be white, gray or pink and it blooms with white summer flowers. The lemon-scented gum grows in USDA zones 8 through 10 and tolerates a range of site conditions, from wet to dry soil and full sun to partial shade.