Pagoda dogwood

Pagoda Dogwood
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Cornales
Family:	Cornaceae
Genus:	Cornus
Subgenus:	Swida
Species:	C. alternifolia
Binomial name
Cornus alternifolia L.f.

Pagoda dogwood (Cornus alternifolia), also known as alternate-leaved Dogwood, is a species of dogwood 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.^[1]

Description

Flowers

It is a small deciduous tree growing to 25 feet (rarely 30 feet) tall, with a trunk up to 6 inches diameter. The branches develop characteristic horizontal layers separated by gaps, with a flat-topped crown. Its leaves are elliptic to ovate and grow to 2-5 inches long and 1-2 inches 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 topside of the leaves are smooth and green, while the undersides are hairy and a bluish color. Its bark is colored gray to brown. It becomes ridged as it ages. C. alternifolia produces small cream colored flowers with four small petals. The flowers are grouped into cymes, with the inflorescences 2-5 inches across. It bears fruit similar to berries with a blackish blue color. These fruits grow 3-4 inches across.

• 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 of cu. ft., 41-73 lbs.
• Winter buds: Light chestnut brown, acute. Inner scales enlarge with the growing shoot and become half an inch long before they fall.

Fruits

• 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, one-third inch across, tipped with remnant of style which rises from a slight depression; nut obovoid, many-grooved. October.^[2]

Habitat

Seedlings

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.

Ornamental use

The tree is regarded as attractive because of its wide spreading shelving branches and flat-topped head, and is often used in ornamental plantings. The flower clusters have no great white involucre as have those of the Flowering Dogwood, and the fruit is dark purple instead of red and of intensely disagreeable aromatic flavor.

C. alternifolia is susceptible to Golden Canker (Cryptodiaporthe corni), particularly when drought stressed or heat stressed. Proper siting of the plant in partial to full shade, along with adequate mulch and water, will reduce incidence of this pathogen.^[3]

References

1. ^ ""Cornus Alternifolia Range Map"". United States Geological Survey. http://esp.cr.usgs.gov/data/atlas/little/cornalte.pdf. Retrieved 2008-02-29. 
2. ^ Keeler, Harriet L. (1900). Our Native Trees and How to Identify Them. New York: Charles Scriber's Sons. pp. 186–189. 
3. ^ Michelle Grabowski. "Golden Canker on Pagoda Dogwood". University of Minnesota Extension. http://blog.lib.umn.edu/efans/ygnews/2009/04/golden_canker_on_pagoda_dogwoo.html. Retrieved 2010-12-20. 

References

1. Trees, by Coombes, Allen J., Eyewitness Handbooks

External references

1. Germplasm Resources Information Network: Cornus alternifolia
2. Trees of Wisconsin: Cornus alternifolia
3. Natural Resources Canada: Cornus alternifolia
4. WLU data page: Cornus alternifolia
5. NRCS: USDA Plants Profile and map: C. alternifolia