Cornus florida

Cornus florida (Flowering Dogwood, syn. Benthamidia florida (L.) Spach) is a species of dogwood native to eastern North America, from southern Maine west to southern Ontario and eastern Kansas, and south to northern Florida and eastern Texas and also in Illinois, with a disjunct population in eastern Mexico in Nuevo León and Veracruz.

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  It is a small deciduous tree growing to 10 m high, with a trunk diameter of up to 30 cm. The leaves are opposite, simple acute oval, 6-13 cm long and 4-6 cm broad, with an apparently entire margin (actually very finely toothed, under a lens); they turn a rich red-brown in fall.

The flowers are individually small and inconspicuous, with four greenish-yellow petals 4 mm long. Around 20 flowers are produced in a dense, rounded, flowerhead 1-2 cm diameter, the flowerhead surrounded by four conspicuous large white or pink "petals" (actually bracts), each bract 3 cm long and 2.5 cm broad, rounded, and with a distinct notch at the apex. The flowers are bisexual.

While most of the wild trees have white bracts, some selected cultivars 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 Kousa Dogwood (Cornus kousa), native to Asia, flowers about a month later.

The fruit is a cluster of three to eight 10-15 mm diameter drupes which ripen to a bright red in the fall; they are eaten by birds which distribute the seeds. The berries are edible, and are remarkably delicious, often being used to sweeten tea in Mexico.

There are two subspecies:

• Cornus florida subsp. florida. Eastern United States, southeastern Canada (Ontario).
• Cornus florida subsp. urbiniana (Rose) Rickett (syn. Cornus urbiniana Rose). Eastern Mexico (Nuevo León, Veracruz).

Ecology

It is very susceptible to dogwood anthracnose, a disease caused by the fungus Discula destructiva. This has killed many wild stocks of Flowering Dogwood; domestic landscape plantings have often been affected to a lesser degree because better air circulation and less humid conditions discourages the fungus, but losses still occur frequently. The Kousa Dogwood is resistant to this disease. Flowering Dogwood leaves serve as foodplants for the caterpillars of some Lepidoptera, e.g. the Io moth (Automeris io).

Cultivation and uses

  Flowering Dogwood does best horticulturally when it has shade from the west but has good morning sun. It does not do well when exposed to intense heat sources such as adjacent parking lots or air conditioning compressors. It has a low tolerance to salt. In eastern North America, it is cultivated as far north as Toronto and south to central Florida. Farther west, places of cultivation include Boulder, Sacramento and Vancouver. It is sold in other temperate parts of the world, including Sydney, Australia.

Selected cultivars

• 'Autumn Gold' - white bracts; yellow fall color.
• 'Barton' - large white bracts; blooms at early age; resists mildew.
• 'Bay Beauty' - double white bracts; resists heat and drought; good for Deep South.
• 'Cherokee Daybreak' - white bract; vigorous grower with variegated leaves.
• 'Cherokee Chief' - red bracts; red new growth.
• 'Cherokee Sunset' - purplish-red bracts; variegated foliage.
• 'Gulf Coast Pink' - best pink flowering dogwood in Florida.
• 'Hohman's Gold' - white bracts; variegated foliage.
• 'Plena' - double white bracts; anthracnose-resistant.
• 'Purple Glory' - red bracts; purple foliage; anthracnose-resistant.
• 'Weaver White' - large white blooms; large leaves; candelabra shape; good in north-central Florida.

Other old names now rarely used include American Dogwood, Florida Dogwood, Indian Arrowwood, Cornelian Tree, White Cornel, False Box, and False Boxwood.

References and external links

• Germplasm Resources Information Network: Cornus florida
• NRCS: USDA Plants Profile: Cornus florida
• Missouriplants: Cornus florida
• Bioimages: Cornus florida