Pagoda dogwood (Cornus alternifolia) is a flowering species of dogwood plant native to eastern North America from Canada to the southern United States in Florida. It attracts bees, insects, bears, and deer.
I. Appearance and Characteristics
Cornus alternifolia is a species of flowering plant in the dogwood family Cornaceae, native to eastern North America, from Newfoundland west to southern Manitoba and Minnesota, and south to northern Florida and Mississippi. It is rare in the southern United States. It is commonly known as green osier, alternate-leaved dogwood, and pagoda dogwood.
It is a small deciduous shrub or tree growing to 25 feet (8 m) (rarely 30 feet (9 m)) tall and 20 feet (6 m) to 32 feet (10 m) wide, with a trunk up to 6 inches (152 mm) in diameter. The branches manifest in horizontal layers separated by gaps, with a flat-topped crown, said to resemble a pagoda.
The alternate-leaf dogwood is a shrub or small tree that has horizontal branches that form tiers. The branches are parallel to the ground creating a layered tiered look with upturned branches like a pagoda. This plant may grow from 15 to 25 feet tall and 20 to 32 feet wide.
Its leaves are elliptic to ovate and grow to 2–5 inches (5–13 cm) long and 1–2 inches (25–51 mm) broad, arranged alternately on the stems, not in opposite pairs typical of the majority of Cornus species. The leaves are most often arranged in crowded clusters around the ends of the twigs and appear almost whorled. The upper sides of the leaves are smooth and green, while the undersides are hairy and a bluish color. The bark is colored gray to brown, becoming ridged as it ages. Small cream colored flowers are produced, with four small petals. The flowers are grouped into cymes, with the inflorescences 2–5 inches (5–13 cm) across. It bears berries with a blackish blue color.
- Bark: Dark reddish brown, with shallow ridges. Branchlets at first pale reddish green, later dark green.
- Wood: Reddish brown, sapwood pale; heavy, hard, close-grained. Sp. gr., 0.6696; weight 41–73 lb/cu ft (660–1,170 kg/m3).
- Winter buds: Light chestnut brown, acute. Inner scales enlarge with the growing shoot and become half an inch long before they fall.
- Leaves: Alternate, rarely opposite, often clustered at the ends of the branch, simple, three to five inches long, two to three wide, oval or ovate, wedge-shaped or rounded at base; margin is wavy toothed, slightly reflexed, apex acuminate. They come out of the bud involute, reddish green above, coated with silvery white tomentum beneath, when full grown are bright green above, pale, downy, almost white beneath. Feather-veined, midrib broad, yellowish, prominent beneath, with about six pairs of primary veins. In autumn they turn yellow, or yellow and scarlet. Petioles slender, grooved, hairy, with clasping bases.
- Flowers: April, May. Perfect, cream color, borne in many-flowered, broad, open cymes, at the end of short lateral branches.
- Calyx: The cup-shaped flowers have four petals that are valvate in bud, unwrapping when in bloom with cream colored, oblong shaped petals with rounded ends. The petals are inserted on disk and the stamens are inserted too and arranged alternately to the petals, being four in number also. The stamens are exserted with filaments long and slender. Anthers oblong, introrse, versatile, two-celled; cells opening longitudinally.
- Pistil: Ovary inferior, two-celled; style columnar; stigma capitate.
- Fruit: Drupe, globular, blue-black, 0.3 in (8 mm) across, tipped with remnant of style which rises from a slight depression; nut obovoid, many-grooved. October.
C. alternifolia is found under open deciduous trees, as well as along the margins of forests and swamps. These trees prefer moist, well drained soil.
Seedlings are shade-tolerant and it is often found as an understory tree in mature forests, such as those dominated by Acer saccharum (sugar maple) or Populus (aspen). It is also common in younger forest.
II. How to Grow and Care
Sunlight
Pagoda dogwood prefers full sun and can grow in a slightly shaded environment. It needs 4-6 hours of sunlight per day; if it does not get enough sun, the plant will grow poorly, the branches will become lighter in color, and the number of flowers and fruit will be fewer.
Temperature and Humidity
This plant likes moderately cool summer temperatures and humidity levels. In hot climates, you may need to provide shade and ensure the soil is mulched to keep it cool.
Watering
Water pagoda dogwood 1-2 times a week. In hot summer or sunny conditions, appropriately increase the watering frequency. When the plant is dormant in winter, it absorbs water at a reduced rate, so you will need to reduce the amount of watering. When watering, be careful not to spray water on the leaves, as too much water on the leaves can cause pests and diseases.
Soil
Pagoda dogwood is very adaptable, but prefers nutrient-rich, well-drained soil. If the soil is poorly drained, improve it by mixing in some sand. It grows best in neutral or slightly acidic soil with a suitable pH of 5.5-6.6.
Fertilizing
Pagoda dogwood does not require much fertilizer. Too much fertilization can lead to excessive growth and weaker resistance. If the soil is poor, add a decomposing organic fertilizer in spring. If you want the tree to bloom and flourish, add some potassium fertilizer. Do not apply fertilizer in the first year of planting, because it may damage the newly grown root system. You can apply fertilizer after one year of growth.
Pruning
Pagoda dogwood does not require much pruning. You need only to cut off dead, injured branches and any parts infected with pests and disease. Prune pagoda dogwood in late fall and winter. If you prune it in spring or summer, the plant is in its growing season and the wounds will shed a lot of sap; in late fall and winter, pagoda dogwood enters dormancy and will not do that.
Propagation
Like other dogwood species, pagoda dogwood is best propagated by rooting stem cuttings. Note, however, that propagating the popular cultivar ‘Golden Shadows’ by any method is prohibited because it is trademarked.
- Cut a 6-inch length of stem from the tip of a branch. Make sure there are 4 to 6 leaves. Pinch off the bottom pair of leaves from the stem, leaving wounds in the stem.
- Fill a small pot with a rooting medium—either a commercial mixture or a make-your-own mixture of sand and perlite. Moisten the rooting medium with water. Dip the bottom 1 1/2 inch of the stem into the rooting hormone. Bury the bottom of the cutting 1 1/2 inch deep in the rooting medium and pack the medium tightly around the stem.
- Place the cutting and pot inside a large plastic bag and seal, ensuring the leaves don’t touch the bag. Check the cutting once a week to see if it has developed roots. Either look at the bottom of the pot to see if roots are coming through or give the stem a gentle tug to see if it is anchored.
- Remove the plastic bag once roots have developed, place the pot in a sunny window, and keep it moist. Fertilize with a diluted liquid fertilizer every two weeks until the plant grows well.
- When the cutting outgrows its pot, move it into a larger pot filled with regular potting soil. Well-established new plants can be transferred to the landscape in the fall.
How to Grow from Seed
If you want to collect seeds from a pagoda dogwood for propagation, make sure it is the straight species. Variegated cultivars cannot be reproduced true to type from seed.
- In the fall, collect the seeds and sow them 1/4 to 1/2 inch deep in a prepared outdoor bed with natural soil. Choose a location where the seedlings will get partial shade during the summer, especially during the hot afternoon hours.
- Mulch and mark the location well.
- The seeds need two to three months of cold stratification at 40 degrees Fahrenheit, followed by temperatures between 70 to 85 degrees Fahrenheit at which the seeds germinate. Overall, it takes 13 to 14 weeks for the seeds to germinate.2
- Once the seedlings emerge in the spring, water them if it does not rain and keep the bed weed-free. Let the seedlings grow for at least another season before transplanting them.
Potting and Repotting
Pagoda dogwood is not a good choice for container growing. In addition to its considerable height and spread, its fibrous, spreading root system needs space. The root zone must be kept cool, which is very difficult for a container plant during the summer.
Overwintering
As a native plant, pagoda dogwood is well adapted to the cold hardiness conditions in its climate range and does not need overwintering protection. It is the hardiest of the dogwood trees, growing well in USDA hardiness zones 3 through 7.
Pests and Diseases
Common Pests & Plant Diseases
Dogwoods are prone to leaf spot, twig and leaf blights, root rot, and canker. Occasional insect pests include scale, leaf miners, and borers. Dogwoods are most susceptible to insect infestation when the lower trunks get wounded by lawnmowers or weed trimmers, so avoid damaging the bark.
Common Problems
Pagoda dogwoods are relatively easy to care for if their growing conditions are met, such as filtered sunlight and cool, moist, well-draining soil. However, they are susceptible to animal damage, some pests, and other issues when conditions are neglected.
Animal Damage
Various types of birds eat the berries of pagoda dogwood (including the ruffed grouse), as does the black bear. This appeal to wildlife also extends to deer and rabbits, which can badly damage the bark and branches of dogwood.3 Young trees are especially susceptible and may need to be protected with fences if rabbits or deer are a problem.
Yellowing Branches or Trunk
Golden canker is a disease spread by a fungus that looks like yellow blisters on the surface of branches, stems, and sometimes the tree trunk. Golden canker does not affect the roots of the tree. However, if it spreads to the main trunk, it will kill everything above the point of infection. It’s only a matter of time before the entire tree dies.
The fungus turns the infected areas bright yellow, orange, or tan and kills the leaves along that branch or stem. Prune away the discolored parts to stop the fungus from spreading; pruning is best done when the tree is dormant in the cold weather months. Sterilize the pruning shears between each cut. Destroy the diseased branches.
Browning Leaves
If you notice browning leaves and you don’t notice golden canker yellowing, it could be leaf scorch if the browning is happening during hot weather. Heat causes dogwood leaves to turn brown along the edges and between the veins. Other heat or water stress signs include drooping, reddening, and curling leaves. Give more water during periods of high heat.
III. Uses and Benefits
- Ornamental uses
Pagoda dogwood is a flowering dedicious small tree or shub. Due to its attractive looks and showy bloom clusters, it can serve well as a specimen tree, or in small groups on lawns, around houses, or near patios. Besides being a showy specimen, it is a great choice for shrub borders and wild-type gardens, especially because it attracts wildlife (namely, birds and butterflies).
- Other uses
Cornus alternifolia has been used in the traditional Chinese medicine as tonic, analgesic, and diuretic.
