Cornus florida, the听flowering dogwood, is a听听of听听in the听听听native to eastern听听and northern听. An endemic population once spanned from southernmost coastal听听south to northern听听and west to the Mississippi River.听The tree is commonly planted as an ornamental in residential and public areas because of its showy听听and interesting bark structure.
Classification
The flowering dogwood is usually included in the dogwood听听听as听Cornus florida听L., although it is sometimes treated in a separate genus as听Benthamidia florida听(L.) Spach. Less common names for听C. florida听include听American dogwood,听Florida dogwood,听Indian arrowwood,听Cornelian tree,听white cornel,听white dogwood,听false box, and听false boxwood.
Description
Flowering dogwood is a small听听听growing to 10听m (33听ft) high, often wider than it is tall when mature, with a trunk diameter of up to 30听cm (1听ft). A 10-year-old tree will stand about 5听m (16听ft) tall. The听听are opposite, simple, ovate, 6鈥�13听cm (2.4鈥�5.1听in) long and 4鈥�6听cm (1.6鈥�2.4听in) broad, with an apparently entire margin (actually very finely toothed, under a lens); they turn a rich red-brown in fall.
Flowering dogwood attains its greatest size and growth potential in the Upper South, sometimes up to 40 feet in height. At the northern end of its range, heights of 30鈥�33 feet are more typical. Hot, humid summer weather is necessary for new growth to harden off in the fall.
The maximum lifespan of听C. florida听is about 80 years.
The听听are individually small, inconspicuous, and a hermaphrodite, with four, greenish-yellow petals (not bracts) 4听mm (0.16听in) long. Around 20 flowers are produced in a dense, rounded,听-shaped听, or flower-head, 1鈥�2听cm (0.39鈥�0.79听in) in diameter. The听听is surrounded by four conspicuous large white, pink or red bracts (not petals), each bract 3听cm (1.2听in) long and 2.5听cm (0.98听in) broad, rounded, and often with a distinct notch at the apex.
When in the wild they can typically be found at the forest edge and frequently on dry ridges. While most of the wild trees have white bracts, some selected听听of this tree also have pink bracts, some even almost a true red. They typically flower in early April in the southern part of their range, to late April or early May in northern and high altitude areas. The similar听听(), native to听, flowers about a month later.
The听听is a cluster of two to ten separate听, (fused in听Cornus kousa), each 10鈥�15听mm (0.39鈥�0.59听in) long and about 8听mm (0.31听in) wide, which ripen in the late summer and the early fall to a bright red, or occasionally yellow with a rosy blush. They are an important food source for dozens of species of听, which then distribute the听. They are also a larval host plant for several moth varieties, including听, the听,听, the听, the听,听the pecan bark borer,听the听,听the听, the听,听,听听moths,听and the听. While not poisonous to humans, the fruit is extremely sour and unpleasant-tasting.[] Flowering dogwood is monoecious, meaning the tree has both male and female flowers, and all trees will produce fruit.
Cultivation
Flowering dogwood does best听听in moist,听听in a site with some afternoon shade, but good morning sun. It does not do well when exposed to intense heat sources such as adjacent parking lots or air conditioning compressors. It also has a low听听tolerance. The听听is 5鈥�9 and the preferred pH is between 6.0 and 7.0.听In urban and suburban settings, care should be taken not to inflict mower damage on the trunk or roots, as this increases the tree's susceptibility to disease and pest pressure.:鈥�98鈥�100鈥�听The common flowering dogwood has been placed on the endangered species list in Ontario.听Sites should be selected for reasonably well-drained, fertile soils; full sun is recommended in high-hazard areas (such as stream or pond banks). New plantings should be mulched to a depth of 5 to 10听cm (2 to 4听in), avoiding the stem. Dead wood and leaves should be pruned and completely removed and destroyed yearly. Plants should be watered weekly during droughts, with watering done in the morning, avoiding wetting the foliage. Registered听听can be applied when necessary, according to manufacturers instructions and advice of local听.
Flowering dogwood is grown widely throughout the 听world.
- Selected cultivars
- 'Amerika Touch-O-Pink' 鈥� large bracts, tinged pink; large leaves; good disease resistance.
- 'Appalachian Spring' 鈥� large white bracts; red fall foliage; resistant to dogwood听.
- 'Autumn Gold' 鈥� white bracts; yellow fall color.
- 'Barton' 鈥� large white bracts; blooms at early age; resistant to stem听听and听.
- 'Bay Beauty' 鈥� double white bracts; resists heat and drought; good for听.
- 'Cherokee Daybreak' 鈥� white bract; vigorous grower with听听leaves.
- 'Cherokee Chief' 鈥� red bracts; red new growth.
- 'Cherokee Brave' 鈥� Even redder than 'Cherokee Chief', smaller bracts but dark red color; consistently resistant to听.
- 'Cherokee Princess' 鈥� vigorous white bracts, industry standard for white flowers.
- 'Cherokee Sunset' 鈥� purplish-red bracts;听听foliage.
- 'Gulf Coast Pink' 鈥� best pink flowering dogwood in听听鈥� northern part only.
- 'Hohman's Gold' 鈥� white bracts;听听foliage.
- 'Jean's Appalachian Snow' 鈥� large, overlapping white bracts w/ green flowers; very resistant to听.
- 'Karen's Appalachian Blush' 鈥� delicate white bracts edged in pink; some听听resistance.
- 'Kay's Appalachian Mist' 鈥� stiff, creamy white bracts; red fall foliage; good resistance to听.
- 'Plena' 鈥� double white bracts; spot听-resistant.
- 'Purple Glory' 鈥� red bracts; purple foliage; spot听-resistant but susceptible to听.
- 'Weaver White' 鈥� large white blooms; large leaves; candelabra shape; good in north-central听.
Propagation
Cornus florida听is easily propagated by seeds, which are sown in the fall into prepared rows of听听or sand, and emerge in the spring.听听rates for good clean seed should be near 100% if seed dormancy is first overcome by cold听听treatments for 90 to 120 days at 4听掳C (39听掳F).:鈥�100鈥�102鈥�听Flowering dogwood demonstrates听听, meaning that the plants can't self-fertilize. This is important for breeding programs as it means that it is not necessary to听听(remove the听听from)听C. florida听flowers before making controlled听. These pollinations should be repeated every other day, as the flowers must be听听within one or two days of opening for听听to be effective.
Softwood 听taken in late spring or early summer from new growth can be rooted under mist if treated with 8,000 to 10,000 ppm听听(IBA). In cold climates, potted cuttings must be kept in heated cold frames or听听the following winter to maintain temperatures between 0 and 7听掳C (32 and 45听掳F). Although rooting success can be as high as 50鈥�85%, this technique is not commonly used by commercial growers. Rather, selected cultivars are generally propagated by听听in late summer or by whip听听in the greenhouse in winter onto seedling rootstock.:鈥�102鈥�
听of flowering dogwood is now used in breeding programs aiming to incorporate resistance to dogwood anthracnose and powdery mildew into horticulturally and economically important cultivars.听听() sections are established in a culture of Woody Plant Medium (WPM) amended with 4.4 渭mol/L 6-Benzyladenine (BA) to promote shoot growth.听Rooting of up to 83% can be obtained when 5鈥�7 week-old microshoots are then transferred to WPM amended with 4.9 渭mol/L IBA.
Diseases
Dogwood anthracnose caused by the fungi听听has caused severe mortality of dogwoods.听In regions where dogwood anthracnose is a problem, homeowners and public land managers are encouraged to know the symptoms and inspect trees frequently. The selection of healthy, disease-free planting stock is essential and transplanting trees from the forest, particularly from mountain forests, should be avoided.听Species of听听cause听.
Historical uses
Native Americans used the bark and roots in a remedy for听; a red dye was also extracted from the roots.听The species has been used in the production of inks,听听dyes, and as a听听substitute. The hard, dense wood has been used for products such as听听heads,听, wooden rake teeth, tool handles, jeweler's boxes and butcher's blocks.:鈥�100鈥�听Cornus florida听is the听听and flower of听,听the听听of听, and听听of听.听It was used to treat dogs with听, which may be how it got its name.听The red berries are not edible, despite some rumors otherwise.
In 1915, 40 dogwood saplings were donated by the听听to听听in the 1912-15 exchange of flowers between听听and听听While the听听trees survived the ensuing sour relations of these two countries and are the main feature of the听, all dogwood trees in Tokyo died except the one that had been planted in an agriculture high school. In 2012, the United States sent 3,000 dogwood saplings to听听to commemorate the 100th anniversary of the Washington, D.C., cherry trees given as a gift to the U.S. by Japan in 1912.