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Woody > Oxydendrum > Oxydendrum arboreum > Oxydendrum arboreum

Oxydendrum arboreum

Sourwood, Sorrel Tree, Lily-of-the-Valley Tree.

Origin:  Native to North America and the southeastern United States of America.
            Mike's Opinion

this is Mike


A beautiful specimen plant with 4 seasons of interest; very flexible in use provided you've met the physical requirements. Like most of the finer things in life, it can be seen as headstrong; having very specific needs. However delicate, it is still a very flexible tree to use in a modern landscape. The beautiful foliage and persisting flowers help change the garden throughout the year. Oxydendrum arboretum should be used as a specimen tree or mass grove to truly appreciate all the qualities it possesses. If all the requirements are met, it will be a very rewarding addition to your landscape.

Michael Pascoe, NDP., ODH., CLT., MSc. (Plant Conservation)


Tree (deciduous), Shrub (deciduous)
USDA Hardiness Zone
5a - 9a
Canadian Hardiness Zone
RHS Hardiness Zone
Temperature (°C)
Temperature (°F)
8 - 9 m
7 - 9 m
Description and Growing Information
Flowering Period
General Description
A slow growing short ornamental tree or shrub with a rounded to pyramidal form. Used as a specimen or massing plant. Has vibrant green spear shaped leaves in summer and a scarlet red colour in autumn. Sweeping strands of white bell shaped flowers in late summer which will persist into autumn.
Used as a specimen or accent tree, shrub or group massing. Typically not used in urban landscapes due to low urban tolerance; requires moist well drained soils. Growth is: wild, undefined, and thick. However, with maturity it becomes more pyramidal in shape. Edible sour tasting leaves have led to its common name Sourwood.
Grows well in moist and well drained acidic soils (4 - 6 pH), and in full sun to partial shade. Full sun will increase flowering and Autumn colour. Has a low urban tolerance due to susceptibility to air pollution, drought and salinity levels.Transplants while young from either balled and burlapped, or container grown. Container grown specimens transplant with ease from any size.
Irregular, thick growth, rounded shape. However, with maturity becomes pyramidal in shape.
ID Characteristic
Simple, alternate, spear shaped leaves, long streams of white bell shaped flowers which persist into autumn and winter. The plant has very deeply scaled bark.
The most common pest for concern is the dogwood twig borer (Oberea tripunctata). Its larvae attack twig health causing twig dieback while adults attack leaves. New buds are susceptible to a cambium weevil (Conotrachelus anaglypticus). Azalea stem borer (Obereamyops), similar in destruction to the dogwood twig borer, also attacks the plant's root system. Additional pests include leaf spot a foliage fungus, and fall webworm a defolliatior.
Native to Southeastern United States, from southern New York to northern Florida. Introduced 1747. Typically found in highland, gravely well drained soils (will tolerate slightly drier sites but will require watering in times of drought).
Bark/Stem Description
Deeply dissected scales, angular, grayish-brown in color, horizontally blocked in appearance, medium to rough texture.
Flower/Leaf Bud Description
Small reddish round/slightly pointed buds are 1 - 3 mm in size. Remnant blooms persist into winter aiding in identification.
Leaf Description
Alternate, Simple, spear shaped, lanceolate, to elliptic-oblong, 8 - 20 cm in length, 4 - 9 cm wide, brochidodromous venation.
Flower Description
White bell shaped masses of swooping lace like panicles, one sided raceme. Relies on pollinators.
Fruit Description
1-3 mm in size, dehiscent Capsules. While young remain pensile, with maturity become raised. Yellow in colour fading to brown as the season closes.
Colour Description
Light green to dark glossy green with age. Autumn colours from yellow to scarlet red to purple, full sun will create vivid autumn colours. White masses of flowers flow on yellowish stalks that fade to brown. Bark is brown in youth and fades to greyish-brown with age.
Texture Description
Medium texture in all stages, noticeably rigid blocks in maturity.
Notable Specimens
Bartlett Arboretum and Gardens, Stamford Connecticut, United States of America. The A.M. Cuddy Gardens, Strathroy, Ontario, Canada.
Propagation from cuttings is difficult/unsuccessful. Seeds have variable dormancy period; germinate in approx. 3 - 4 weeks.