Three Small Flowering Trees - April 28, 2010
Jeff Schalau, Associate Agent, Agriculture & Natural Resources
University of Arizona Cooperative Extension, Yavapai County
Many people ask the Extension office about suitable tree species for the Verde Valley area. Before you select a tree, determine how much space is available for its growth. Often people plant fast growing trees. In a few years, they are faced with a tree that has outgrown its available space and it requires severe pruning. This diminishes its attractiveness and can shorten its life if done incorrectly. In addition, many of the fast-growing, larger trees are wind pollinated and can cause pollen allergies. Trees having attractive flowers are usually insect pollinated and do not saturate the air with allergy causing pollen. Below are three small, deciduous flowering trees suitable for the Verde Valley.
The chaste tree (Vitex agnus-castus) is a small, often multi-trunked tree that can grow from 10 to 18 feet tall. It is a tough, drought-resistant plant hardy from zones 6 to 9. The chaste tree is native to Western Asia and southern Europe and is a member of the mint family (Lamiaceae). It has palmately compound leaves with five to seven leaflets which when crushed, have a distinctive aroma. Blue to violet spikes of flowers are produced early- to mid-summer on the ends of new shoots. If provided with regular irrigation, they continue to flower on and off during the summer. White and pink flowered forms are also available. It needs full sun to flower and is relatively pest and disease free.
After flowering, the chaste tree’s bloom spikes are covered with peppercorn-sized rounded fruits. It is from these fruit that chaste tree derives its common name. The Greeks believed an extract from the fruits calmed sexual passions and cured various female ailments. Interestingly, it also goes by the common name monk’s pepper. It is a favorite of bees, butterflies and hummingbirds, so put it where it can be seen from patios and decks. Many beekeepers seek out chaste tree as a summertime nectar source.
The desert willow (Chilopsis linearis) is another excellent drought tolerant tree for north central Arizona. Desert willow is not a true willow, but a close relative of the catalpa tree and a member of the trumpet vine family (Bignoniaceae). This deciduous, native tree/shrub can be found along dry washes and seasonal creeks in desert, chaparral, and grassland habitats between 1,500 and 5,000 foot elevations. It is hardy to zones 8 and 9 and requires little water once established. The desert willow is very graceful with an airy, open canopy, can grow to 20 feet tall by 20 feet wide and is usually multi-trunked. Its narrow, curving leaves are between 3 and 5 inches long and 1/4 to 1 inch wide.
They look very graceful but have a surprisingly tough, leathery texture. Desert willows are best known for their showy flowers which appear in clusters on branch tips from late spring to early summer and can vary in color from white to deep purple with yellow spots or stripes in the throat of the trumpet-shaped blossoms. With some additional irrigation, they can bloom through September. In addition, the flowers have a sweet fragrance that attracts bees, butterflies, and hummingbirds.
The crepe myrtle (Lagerstroemia indica) is a vase-shaped, multi-trunked shrub but nurseries often produce single trunked trees which can reach 20 ft in height. It is a native of China and a member of the Lythraceae family (along with pomegranates). The bark of this tree is very attractive with a smooth, tawny, mottled appearance. They should be planted in full sun for optimum flowering. Cultivars vary in their cold hardiness (USDA Hardiness Zones 7-9) and flower color ranges from white to lavender. The flowering period is throughout the summer and the leaves are small and oblong. Fall color of leaves depends on the cultivar, but ranges from none to crimson and yellow.
Crepe myrtles are somewhat less drought-tolerant than the chaste tree and desert willow. Supplemental irrigation during dry periods will provide better growth and flowering. Crepe myrtles have relatively thin bark and can be easily damaged by lawn mowers and string trimmers.
The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at firstname.lastname@example.org and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/.
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Last Updated: June 21, 2010
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