Belonging to the family Comaceae of genus Cornus, dogwood is generally a shrub or small woody deciduous tree. The species bears oval shaped leaves that are prominently veined and pointed at the end. The leaves have a deep green color on the upper surface, while underneath it is whitish and usually velvety. The shrubs/ trees bear tiny greenish-white flowers in May-June. These diminutive blooms form a central cluster that is surrounded by four ostentatious, serrated, creamy white bracts that resemble petals. The flowers of dogwood produce fruits that are red in color.
The inhabitants of Virginia love dogwood so dearly that they have named this species as their state tree. One of the early natives of America, George Washington had mentioned in his diary way back in 1785 that ‘a ring of dogwood' has been planted near the old cherry close to the south garden house. Another well known personality from Virginia who is known for his flawless taste and appreciation of things beautiful, Thomas Jefferson too planted dogwood close to Monticello - his treasured home.
When dogwood started blooming during the spring, the attractive creamy white bracts that have resemblance to petals gave a signal to the native Indians that it was the right time to plant corn. In addition, the dogwood tree was also a source of medications for these Native American Indians. They boiled the bark of dogwood in water and utilized the extract to ease sore and painful muscles. In addition, they also prepared an herbal tea with the bark to stimulate perspiration and, thereby, cure a fever. In fact, this traditional remedy was also adopted by physicians and herbalists at a later period. When the southern ports were blocked during the American Civil War making it difficult to obtain cinchona bark - the source of quinine used in treating malaria, people used the bark of dogwood as an effective substitute.
Dogwood trees are also valued for their exceptionally solid timber that has been used for making different types of objects such as golf club heads.
The dogwood tree has a number of therapeutic properties and, hence, it has been traditionally used to treat a number of medical conditions. Earlier, the bark of the dogwood tree was extensively used to break a fever as well as a substitute for quinine for treating sporadic or recurring fevers like malaria. These days, the herbal tea prepared with dogwood bark is mainly considered to promote appetite. However, there is no scientific proof that any of these uses of dogwood bark are effectual.
In addition to its remedial uses, blooming dogwood trees are among the most popular ornate specimen trees in the eastern regions of North America. Dogwood may be used as a framing tree or, alternately, as a background tree. They look wonderful when grown beneath huge oak and pine trees. In effect, dogwood shrubs/ trees are one of the first springtime bloomers, cheering up the landscape in company with other species, such as spireas, azaleas, redbud and forsythia. Since the dogwood trees have a thick crown, blooming dogwood provides excellent shade. Moreover, owing to the small structure of dogwood, it is also of use even in the smallest backyards.
The timber of the dogwood tree is extremely tough and to a certain extent it is valued in the trade of forest products for things, such as commercial spindles and loom shuttles. During the days of colonialism in the United States of America, an herbal tea prepared with the bark of dogwood tree was known to alleviate fevers. The attractive red fruits of the dogwood are a favorite food for the squirrels and birds.
Habitat and cultivation
Dogwood is indigenous to North America and is found growing over a wide expanse from southern Ontario and Maine south to Florida and Texas and to Kansas in the west. In horticulture, flowering dogwood thrives well in damp, acidic soil in a place which receives some amount of shade in afternoons, but adequate sunlight during the mornings. This tree cannot tolerate too much heat or when grown close to heat sources, for instance, near parking lots or air conditioning compressors. In addition, dogwood also has a low tolerance of salinity. When grown in urban as well as semi-urban locales, sufficient care ought to be taken not to impose mower damage on the trunk or roots of dogwood trees, since this enhances the vulnerability of the tree to diseases as well as invasion by pests.
In areas where growing the dogwood tree is somewhat a problem, both homeowners as well as public land managers are persuaded to learn about the symptoms as well as examine the trees at frequent intervals. In effect, it is vital to select healthy and disease-free planting stock as well as to avoid transplanting trees from the forest. The locations that need to be selected should be reasonably well-drained, have fertile soils and receive full sunlight in high-hazard areas, for instance banks of ponds or streams. All new plantings ought to be mulched (covered with organic matter) to a depth of two to four inches (5 cm to 10 cm) keeping away from the stem. In addition, every year, care should be taken to cut all dead wood and leaves and remove them completely. During the periods of droughts, the plants need to be watered regularly in the mornings keeping in view that the foliage is not drenched. As and when necessary, enlisted fungicides may be applied to the young trees strictly following the instructions provided by the manufacturers.
Dogwood can be propagated without much difficulty by its seeds. The seeds of dogwood are sown in the fall into organized rows of sand or sawdust and the seedling usually emerge in the ensuing spring. If you are using clean seeds the germination rate is excellent, almost 100 per cent. In fact, the dormancy of the seeds is prevailed over by means of cold stratification treatments for about 90 to 120 days (three to four months) at around 4°C (39°F).
The flowering dogwood shows gametophytic (the sexual type of a plant in the swinging of generations) self-incompatibility. In other words, this denotes that the dogwood plants are not able to self-fertilize. This is a vital issue for breeding programs since it denotes that it is not essential to emasculate or remove the anthers from Cornus florida (dogwood) prior to making controlled cross-pollination. Such pollinations need to be repeated every alternate day, since the flowers should be cross-pollinated inside one or two days of opening for pollinations to be effectual.
Alternately, dogwood may also be propagated by softwood cuttings taken from new growth in the later part of spring or early part of summer and rooted under mist provided they are treated with 8,000 to 10,000 ppm indole-3-butyric acid. If the process is followed in cold climatic regions, the potted cuttings ought to be kept in heated cold frames or polyhouses during the following winter with a view to keep up temperatures between 0°C and 7°C. While the success of rooting can be as high as 50 per cent to 85 per cent, this method is not generally used by commercial cultivators. Instead, selected cultivable varieties are usually propagated by a method called T-budding in the later part of summer or by means of another method known as whip grafting in the greenhouse during winter months onto seedling rootstock.
Chemical analysis of dogwood tree has revealed that it encloses an iridoid glycoside called verbenalin, quinine, saponins and tannins. It has been found that verbenalin has a gentle effect on the involuntary nervous system particularly that controls the digestive system.