Scientific Facts

Dogwood, common name for a family of flowering plants distributed mainly in the temperate areas of the northern hemisphere, with a few species occurring in tropical South America and Africa. Of the 14 genera in the family, only the dogwood genus is native to North America. Members of the family are mostly trees or shrubs with simple, opposite leaves. Well-known exceptions, however, are the bunch berry, a perennial herb; and the pagoda dogwood, which has alternate leaves. Dogwood flowers are small and are produced in branched terminal clusters that are sometimes surrounded by showy white bracts. Thus, the so-called petals of the familiar flowering dogwood are actually bracts.

The main economic importance of dogwoods stem from their valuable ornamental species, grown for their attractive flowers, flower bracts, fruits, twigs and stems, and colorful autumn leaves. In addition to the species already mentioned, most of which are commercially grown, others commonly found in cultivation include the Cornelian cherry, the red-osier dogwood, the Japanese dogwood, and certain sour gums (see SOUR GUM). The fruit of the Cornelian cherry, a native of Europe, is used in France to make an alcoholic beverage, vin de courneille, and is also used in preserves. Oil extracted from the fruit of the blood-twig dogwood is used in France for making soap. The wood of several species is used in furniture.

The order to which the dogwoods belong contains 4 families and about 150 species, about 100 of which are in the same family as dogwoods. The sour gum family contains three genera. The two other families both contain one genus. Members of the order vary greatly in flower structure, making the order difficult to characterize. The flowers are usually small, however, with the four or five sepals commonly reduced in size and forming a tube that is fused to the ovary (female flower part). A nectar-producing disk is usually present on the upper part of the ovary. Four or five petals are commonly found; they are not fused to one another. Occasionally, however, the petals are absent.

Scientific classification: Dogwoods make up the family Cornaceae, in the order Cornales. The bunch berry is classified as Cornus canadensis, the pagoda dogwood as Cornus alternifolia, the flowering dogwood as Cornus florida, the Pacific dogwood as Cornus nuttalli, the Cornelian cherry as Cornus mas, the red-osier dogwood as Cornus stolonifera, the Japanese dogwood as Cornus kousa, and the blood-twig dogwood as Cornus sanguinea. The sour gums commonly found in cultivation are classified in the genus Nyssa, in the family Nyssaceae. The two other families in the order Cornales are Alangiaceae and Garryaceae.

Contributed by: Marshall R. Crosby

Powdery Mildew symptoms on Dogwood Powdery Mildew (fungus - Phyllactinia guttata): White, powdery growth develops on foliage. Tender, developing leaves are more susceptible than mature leaves. Heavy infection results in leaf distortions.

When dogwoods flowered in the spring, it indicated the planting time for corn. Ceremony: The leaves of some varieties of Dogwood were used in smoking mixtures including Red Osier dogwood (C. stolonifera) and the C. rugosa type of dogwood. The root of C. alternifolia was also used in a charm that was applied to muskrat traps. Medicine: C. alternifolia was used to make an eye medicine by the Chippewa. The bark was simmered in water and used on aching muscles and a bark tea was used to promote sweating and break a fever. Technology: The inner bark of Red Ossier dogwood was used in mixtures for red, black and yellow dyes. The hardness of the wood makes it good for carving durable items.

Dogwood: Leaf scorch and leaf roll Biology: Leaf scorch and leaf roll are results of stress. Leaf scorch is characterized by browning of the tips and margins of the leaves. Leaf roll is a puckering and upward rolling of the leaf along the midvein. The undersides of rolled leaves are often pinkish or purplish. Drought, heat stress, overwatering, and construction damage are possible causes of both problems. Leaf scorch can also be caused by over-fertilization. Similar symptoms can be caused by herbicide damage. Management Options: Non-chemical: Provide proper irrigation and fertilization for your plants, especially during dry weather. Overwatering and underwatering can both cause leaf scorch. Overfertilization can lead to salt injury on leaf tips and margins. Try to prevent injury to the roots and trunk, especially during construction or soil excavation. Avoid compacting soil, which inhibits water penetration into the soil and reduces drainage. For more information see EB 1422, Leaf Scorch of Shade Trees. Pesticides: None recommended.

DOGWOOD AS HERBAL MEDICINCE In some subjects it cures violent toothache, neuralgia and whooping-cough. It promotes sleep and acts as an antispasmodic in asthma. It dilates the pupil and is helpful with dysmenorrhea and nervous debility. In some people it may cause gastric distress and nausea; overdoses produce toxic effects.

PROPOGATION Manual of woody Landscape Plants by Michael Dirr describes seed propagation as requiring stratification at 41 degrees F for 100 to 130 days. On the chance you want to clone this plant, it roots readily from softwood cuttings collected immediately after flowering. Stick in sand, peat or pearlite for 8 to 10 weeks. Keep moist with mist if possible or high humidity at a minimum. Dirr suggests dipping in IBA rooting hormone. Seed propagation however can work to our advantage in keeping populations genetically diverse and therefore less likely to succumb to catastrophic disease or parasite infestations.

Among the early spring-flowering trees, the dogwood, Cornus florida, is regarded by most North Carolinians as unrivaled in attractiveness either in its natural woodland habitat or in cultivated landscape gardens. This small ornamental tree offers landscape interest for all seasons. Beginning with its floral display in spring, either in white or pink, and followed by pleasant green foliage (casting a light shade) in summer. Fall in North Carolina is enhanced by the brilliant show of red, orange and scarlet foliage along with the bright red fruit borne in small clusters. In winter, button shaped buds are prominent on the tips of the twigs. The interesting bark texture and branches help create an excellent winter silhouette.

Landscape Use Dogwoods have a variety of landscape uses. With the year-round interest dogwoods are excellent for specimen or accent plantings around the terrace or patio. Often a combination of rhododendrons, azaleas and dogwoods planted in a raised bed creates an interesting landscape feature. Dogwoods make excellent understory trees in a shaded area and are now being used in conjunction with typical foundation plantings and groundcovers.

Culture Dogwoods are easily grown in lawn and garden areas all across the state, adapting itself to various exposures and soil types. Generally, growing to a height of 20-30 feet with a low, broad head and tiers of horizontal branches the dogwood is considered a "well-behaved"tree -- and requires very little maintenance. When planting dogwoods be certain to provide good drainage. The most favorable soil is moist, fertile loam slightly acid to neutral (pH 5.5-6). The addition of peat or leaf-mold improves nearly all soils for the dogwood. A 3-4" layer of organic mulch, replenished occasionally, is beneficial as it keeps soil moist near the surface where the roots are most active, discourages weeds from growing, and most of all offers protection to the trunk from mowers and other equipment. The optimum transplanting time is fall and winter. It is helpful to root-prune dogwood a season before transplanting. However, trees grown in containers are transplanted throughout the year. Nursery-grown trees that have been root-pruned and grown in full sunlight are far superior to those dug up in the woods. In most cases their cost is well justified by quicker recovery after transplanting and better formed tops even where the wild trees are available locally and can be obtained for little more than the cost of digging them. After planting and during the first few years of establishment the most important cultural aspect is to provide ample water during dry stressful periods. Dogwoods are also susceptible to a very serious insect pest which can lead to general decline of the tree. The dogwood borer larvae is mainly a problem to trees which have been physically injured (lawn mowers too close to trunk) as the larvae need an injured area in order to penetrate the bark. Remember to mulch well around base of tree, brace newly planted trees to prevent wind damage, and wrap the trunks of newly transplanted trees with burlap or tree wrap paper the first year of growth.

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