Scholar Tree or Sophora. A member of the pea family, with compound leaves and cream-white flowers in midsummer. Tolerates dust and soot of cities.
Sourwood or Oxydendrum. Small summer-flowering tree, with drooping clusters of small, fragrant flowers and lustrous leaves that turn scarlet in autumn. In containers, specimens can easily be provided with the acid soil they need.
Stewartias. In summer, the Japanese stewartia has white
blooms with orange stamens, and the showy stewartia has white blossoms with purple stamens. Both have colorful autumn foliage and rough barks.
Weeping Willows. Among the best trees for rooftops because they withstand wind. Fast growing, they need periodic replacement, but young plants are moderately priced. The Golden Weeping Willow has bright yellow twigs in winter and chartreuse catkins in early spring.
This is only a partial list of hardy trees for the container garden. Almost any kind can be grown if in scale and given the necessary care. Do not overlook fastigiate forms-upright lindens, oaks, sugar and Norway maples -since these take up little space.
Tender trees are commonly grown in warmer regions, where they remain outdoors all year. In colder areas, as container subjects, they require shelter in winter. As a group, they are popular with both southern and northern gardeners.
Acacias. Many kinds of acacias are treasured for their feathery yellow flowers in winter and early spring. Fast growing, they require a cool greenhouse or plant room in the North in winter.
Bullbay Magnolia. A highly ornamental evergreen magnolia, much grown in the South, with large dark green leaves and huge fragrant white flowers. Where not hardy, a most worthwhile container plant.
California Pepper Tree. A semipendulous small tree, with fernlike, olive-green leaves and hanging clusters of long-lasting, rose-colored berries. A native of Peru, it withstands heat and dryness, even poor soil, as well as severe pruning. Much planted as a street tree in southern Europe.
Citrus. Glossy-leaved trees, with small, scented flowers and decorative, lasting fruits. Orange, lemon, kumquat, tangerine, lime, and others do well in tubs and boxes. The dwarf Otaheite or Tahiti orange and the Ponderosa lemon are small types.
Crape Myrtle. The "lilac of the South," a shrub or small tree, with great tresses of crinkled blooms in pink, red, purple, and white all summer long. Container-grown in the North, it must be wintered in a cool frost-free place. It withstands severe pruning.
Eucalyptus. Rapid-growing, drought-resistant trees with leathery aromatic leaves and peeling bark. Replacements of container specimens are easily made.