The “Crown Jewels” of the Washington Park Arboretum

September 11th, 2016 by UWBG Horticulturist

A tribute to our late Director, Dr. Sarah Reichard.  May she forever garden in peace amongst a grove of Stewartia, her favorite tree.

[Editor’s Note: If you have time to experience their true beauty, it is highly recommended you visit our Stewartia Collection. The smart phone version of our interactive map can be used to pin-point specific locations and information for mature specimens of the species listed below.]

Selected Stewartia cuttings from the Washington Park Arboretum, September 5-18, 2016


Stewartia monadelpha

Close-up photo of Stewartia monadelpha

1) Stewartia monadelpha                (Tall Stewartia)

  • Small tree with an upright growth habit.
  • Foliage turns an excellent maroon color in the fall.
  • Bark is cinnamon-brown and smooth in maturity, scaly rich brown in younger specimens.
  • Flowers are 1 to 1.5 inches wide, white with yellow stamens, and bloom over a month-long period, starting in early summer.
  • Stewartia have fuzzy woody capsules for fruit (see specimen samples).
  • Prefers partial shade.
  • Native to Japan


2)  Stewartia ovata               (Mountain Stewartia)

  • Large shrub with dramatic orange-to-scarlet foliage in fall.
  • Large, showy white flowers have five to six crimped petals, purple to white filaments, and are 2 to 4 inches wide.
  • Summer blooming
  • Native to southeastern U.S.


Close-up photo of Stewartia pseudocamellia var. koreana

Close-up photo of Stewartia pseudocamellia var. koreana

3) Stewartia pseudocamellia var. koreana                (Korean Stewartia)

  • Small tree, whose dark green foliage can turn into a beautiful red to reddish-purple color in the fall.
  • Flowers are large (three inches across), white with yellow stamens, and bloom sporadically over the entire summer.
  • The bark is flaky with the color ranging from grayish-brown to orange-brown, is often mottled, and very attractive.
  • Native to Korea

4)  Stewartia rostrata

  • Rare Stewartia from China
  • White fragrant flowers with gold stamens and maroon bracts
  • Reddish-purple fall color

5)  Stewartia sinensis               (Chinese Stewartia)

  • This tree is the smallest of the Asian Stewartia spp.
  • The flowers are four inches across in June to July.
  • The bronzy new growth turns green all summer, then to the most brilliant, glowing red in fall.

Late Summer Pods & Flowers on Display at the Washington Park Arboretum

August 24th, 2016 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (August 22, 2016 - September 5, 2016)

Selected cuttings from the Washington Park Arboretum
(August 22, 2016 – September 5, 2016)

1)  Hydrangea macrophylla ‘Lanarth White’                         Bigleaf Hydrangea

  • This deciduous shrub, native to Japan, is popular in American gardens.
  • This pure white, lace-cap cultivar is an Elisabeth C. Miller Botanical Garden “Great Plant Pick”.
  • You can find a group of these in the Camellia Collection, west of Arboretum Drive.

2)  Koelreuteria paniculata                  Golden Rain Tree

  • Koelreuteria paniculata is a deciduous tree native to China.
  • This unusual tree shares the same family (Sapindaceae) as Maples (Acer).
  • Its small yellow flowers are followed by showy, inflated seed pods.
  • This and another species of Koelreuteria can be seen along Foster Island Drive.

3)  Neolitsea sericea

  • Neolitsea sericea is native to Japan, China, and Korea.
  • This small evergreen tree is a dioecious member of the Lauraceae family.
  • The young leaves emerge covered with golden-brown indumentum.
  • Several examples can be found along the Upper Trail, south of the Magnolias.

4)  Persea yunnanensis

  • Persea yunnanensis is a native of China’s Yunnan Province.
  • This is a handsome broadleaf evergreen tree, growing to 30 feet or more.
  • It is in the same genus as Avocado, but does not bear the same large, fleshy fruit.
  • A nice example can be seen west of Lot 8, south of the Magnolia Collection.
Rosa corymbulosa photo by Joy Spurr

Rosa corymbulosa (Photo by Joy Spurr)

5)  Rosa corymbulosa                Chinese Species Rose

  • This deciduous shrub is native in China’s Hupeh and Shensi Provinces.
  • Rosa corymbulosa is noted as having few thorns and for bearing flowers in corymbs of up to twelve blossoms.
  • The deep-pink flowers are followed by elongated coral-red fruit in late summer.
  • A specimen can be found on the east side of the Crabapple Meadow near the service road.

August Color Appears at the Washington Park Arboretum

August 14th, 2016 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (August 8 - 21, 2016)

Selected cuttings from the Washington Park Arboretum
(August 8 – 21, 2016)

1)  Clerodendrum bungei

  • C. bungei is a deciduous, suckering shrub producing upright shoots and opposite, ovate, toothed, dark green leaves tinged with purple when young.  Salverform, fragrant, dark pink flowers, each with five spreading lobes, are borne in rounded, terminal panicles from late summer to autumn.  Native to China and a member of the family Lamiaceae, this specimen is happily spreading around the south side of bed ‘G’ on Azalea Way.

2)  Fuchsia magellanica

  • F. magellanica is an erect shrub with ovate-elliptic leaves, sometimes tinted red beneath.  Throughout summer, it produces small flowers with red tubes, wide-spreading sepals, and purple corollas.  Native to Chile and Argentina, this specimen is located within our Pacific Connections Entry Garden along the circular path.

3)  Hibiscus  x  ‘Tosca’

  • A member of the Malvaceae plant family, Hibiscus is a genus of some 200 species of trees, shrubs, and herbs – inhabitants mainly of the tropics and subtropics.  This rather unspectacular specimen is located near Azalea Way, south of the large Glen Pond.

4)  Sorbus  ‘Birgitta’

  • Sorbus is a genus of about 100 species of deciduous trees and shrubs within the family
    Rosaceae.  They are widely distributed throughout northern temperate regions and are
    found in woodlands, on hills and mountains, and on scree.  Tolerant of atmospheric pollution,
    they are ideal as specimen trees in a small garden.  The raw fruit may cause mild stomach upset if ingested.

5)  Vitex agnus-castus and Vitex agnus-castus  ‘Silver Spire’

  • Another member of the family Lamiaceae, Vitex is a widespread genus of around 250
    species of deciduous or evergreen shrubs occurring mainly in tropical regions and often in woodland or dry river beds.  Cultivated for their elegant foliage and summer flowers, Vitex may be grown in a shrub border or against a wall.  These specimens are located along Azalea Way near the Lower Woodland Pond


“One is the loneliest number…”

July 29th, 2016 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum <br /> (July 25 - August 7, 2016)

Selected cuttings from the Washington Park Arboretum
(July 25 – August 7, 2016)

The University of Washington Botanic Gardens is home to truly one of a kind plants.  In botanical nomenclature, a monotypic genus refers to the case where a genus and only a single species are described.  These plants are often “living fossils”, comprising the last living remnant of ancient lineages.  Many are also often in the IUCN Red List of Threatened Species.

1)   Davidia involucrata var. vilmoriniana               Dove Tree

  • Davidia involucrata is the only member of the genus Davidia.  It was named after French priest and naturalist, Father Armand David who was also the first westerner to describe the giant panda.  In 1899, David commissioned a young Kew-trained botanist named Ernest Wilson to travel to China to find the dove tree.  This presented a challenge for 22-year-old Wilson, who had never been abroad before and did not speak a word of Chinese.

2)  Franklinia alatamaha                Franklin Tree

  • William Bartram was the first to report the extremely limited distribution of Franklinia.  “We never saw it grow in any other place, nor have I ever since seen it growing wild, in all my travels, from Pennsylvania to Point Coupe, on the banks of the Mississippi, which must be allowed a very singular and unaccountable circumstance; at this place there are two or 3 acres of ground where it grows plentifully.” (W. Bartram 1791: 468).  The tree was last verified in the wild in 1803 by the English plant collector, John Lyon.

3)  Ginkgo biloba                Maidenhair Tree

  • The Maidenhair Tree was thought to have become extinct, similarly to the other members of its ancient lineage, until it was discovered in Japan in 1691.  The Maidenhair Tree remains virtually unchanged today and represents the only living bridge between ‘higher’ and ‘lower’ plants (between ferns and conifers).

4)  Metasequoia glyptostroboides                Dawn Redwood

  • Considered one of the greatest botanical finds of the 20th century, the Dawn Redwood was known only from ancient fossils until a small population was discovered in the forests of central China in 1944.  The mature, large trees have all been declared protected; habitat protection is overall inadequate, which means that the survival of this very interesting species in its natural habitat is not guaranteed. (Bartholemew 1983, Fu and Jin 1992, Wang and Guo 2009).

5)  Pseudolarix amabilis                Golden Larch

  • The famous plant explorer, Robert Fortune first saw this unusual conifer as a container plant in China.  Wild specimens have been found in the Wuyi Shan of Fujian, and in the Lushan of Jiangxi.  Mixed mesophytic forests have been set aside as protected reserves on the Tienmu Shan and Lu Shan, and these include some of the most diverse temperate forests on earth.

July Color Appears at the Washington Park Arboretum

July 15th, 2016 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (July 11 - 24, 2016)

Selected cuttings from the Washington Park Arboretum
(July 11 – 24, 2016)

1)  Colutea orientalis                Bladder Senna

  • This deciduous native of northern Iran has delicate bluish-green pinnate leaves.
  • The orange flowers are followed by surprising translucent bladder-like fruit pods.
  • You can find Colutea orientalis in the Legume Collection along Arboretum Drive.

2)  Hydrangea macrophylla  ‘Mme. Emile Mouillere’ Bigleaf Hydrangea

  • Hydrangea macrophylla is native to Japan.
  • This cultivar is an example of the Hortensia group – having mophead flowers.
  • The pure white sterile flowers will age to pink.

3)  Hydrangea serrata  ‘Bluebird’                Tea of Heaven

  • Hydrangea serrata, a.k.a. H. macrophylla subspecies serrata, is native to Korea as well as Japan.
  • This cultivar is a fine, long blooming example of the Lacecap group.
  • Many of our hydrangeas can be found in Rhododendron Glen along Arboretum Drive.

4)  Lomatia myricoides                 River Lomatia

  • Lomatia myricoides is a native of Australia, in the regions of New South Wales and Victoria.
  • The flowers are honey scented.
  • A large specimen is located along the east side of Arboretum Drive opposite our New Zealand Garden.

5)  Taiwania cryptomerioides                Coffin Tree

  • This native of southeast Asia is listed as ‘vulnerable’ on the IUCN Red List overall, and ‘critically endangered’ in Vietnam.
  • The wood from this tree has been historically used for coffins.
  • Specimens can be found along Arboretum Drive, on the north side of our Giant Sequoia grove, as well as in the Pinetum.

Summer Arrives at the Washington Park Arboretum

July 3rd, 2016 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum, June 27 - July 10, 2016

Selected cuttings from the Washington Park Arboretum,
June 27 – July 10, 2016

1)  Cunninghamia lanceolata                (Chinese Fir)

  • Bluish evergreen foliage contrasts nicely with its scaly bark.
  • This evergreen tree from China is an important timber tree in its native area.
  • In 1701, James Cunningham (one of the first European plant hunters to visit China) described and collected this tree.

2)  Hydrangea integrifolia                                                      (Evergreen Climbing Hydrangea)

  • A vigorous, evergreen vine climbing to over 40 feet, on the trunk of a mature Douglas Fir.
  • Attractive, large and round creamy buds form prior to the flower opening.
  • Native to Taiwan and the Philippines.

3)  Magnolia grandiflora                (Evergreen Magnolia)

  • The large fragrant blossoms are the highlight of this tree.
  • Native to the southern United States, this tree is popularly planted in urban environments around Puget Sound.

4)  Ostrya carpinifolia                (European Hop Hornbeam)

  • The name Ostrya is derived from the Greek word ostrua, meaning “bone-like”, and refers to the very hard wood.
  • The fruit clusters resembling hops hang from the branches and provide a nice contrast with the foliage and rough bark.
  • Native to southern Europe, Asia Minor and the Caucasus.

5)  Picea koyamae               (Koyama’s Spruce)

  • The immature purplish cones are great color against the green needles.
  • This evergreen tree, from a small mountainous region in Japan, has a threatened status as native stands have been damaged from wildfires and typhoons.
  • Botanist Mitsuo Koyama discovered a small stand of these trees in 1911.

The Wonderful World of Monocots

June 7th, 2016 by UWBG Horticulturist

Monocotyledons, commonly referred to as monocots, are flowering plants whose seeds typically contain only one embryonic leaf, or cotyledon.  A quarter of the world’s known plants are monocots. They are the most economically important group of plants to humans today in agriculture, horticulture, forestry and fiber industries.  Here are a few samples of monocots in our plant collections.

Selected cuttings from the Washington Park Arboretum or Center for Urban Horticulture (June 1 - 12, 2016)

Selected cuttings from the Washington Park Arboretum or Center for Urban Horticulture (June 1 – 12, 2016)

1)  Allium schubertii                                                                            (Ornamental Tumbleweed Onion)

  • Dried seed heads look like starry tumbleweeds or shooting star fireworks
  • Located in the Soest Herbaceous Display Garden, bed 6 at the Center for Urban Horticulture

2)  Austroderia richardii syn Cortedaria r.                     (Toetoe Grass, Plumed Tussock Grass)

  • Ornamental grass native to New Zealand
  • This “pampas” grass seems to be behaving itself in the Pacific Northwest, unlike others that do seed around and could be considered invasive.

3)  Phormium colensoi                (Mountain Flax, Wharariki)

  • One of two species in the genus Phormium; both are endemic to New Zealand.
  • Fiber from its broad, sword-like leaves, can be made into Maori baskets.

4)  Phyllostachys nigra                 (Black Bamboo)

  • Native to China, but widely cultivated elsewhere
  • Known for its ornamental beauty and prized for decorative woodworking
Close-up photo of fruit from a Chinese Windmill Palm tree

Close-up photo of fruit from a Chinese Windmill Palm

5)  Trachycarpus fortunei                (Chinese Windmill Palm)

  • Only palm that is reliably hardy to the Puget Sound area
  • Dioecious, with male and female flowers produced on separate trees
  • Sample of mature fruit cluster and frond

To locate specimens of these plants, please visit our interactive map:

Spring Pushes Forth at the Washington Park Arboretum

May 23rd, 2016 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (May 16 - 30, 2016)

Selected cuttings from the Washington Park Arboretum
(May 16 – 30, 2016)

1)   Ostrya carpinifolia                Hop Hornbeam

  • This small-to-medium-sized tree (40-50’) is native to southern Europe and southwestern Asia.
  • The common name refers to the fruit which resembles the fruit of Humulus (Hops).
  • Ostrya is from Greek, meaning “bone-like” in reference to the trees dense hard wood.
  • Located north of East Foster Island Road, east of the Broadmoor entrance.

2)  Picea mariana ‘Doumetii’                Doumet Black Spruce

  • This selection of Picea mariana is a popular slow-growing shrub with blue green needles and a dense conical growth habit.
  • Located along Arboretum Drive on the north end of the Magnolia Collection.

3)  Pinus x schwerinii                Schwerin’s Pine

  • Schwerin’s Pine is an interspecies cross between Himalayan White Pine (Pinus wallichiana) and Weymouth Pine (Pinus strobus). It was found by Earl Schwerin in his park in Wilmersdorf (near Berlin, Germany) in 1905.
  • Our fine specimen is located north of the Crabapple Meadow near the service road.

4)  Pterocarya macroptera                Large–Winged Wingnut

  • Native to northern China, the Wingnut is a fast-growing, medium height tree to 50-70 feet tall and 40 feet wide.
  • This tree boasts ornamental spikes of fruit with broad wings in long pendulous spikes.
  • This tree can be seen in fruit east of Arboretum Drive and south of the Crabapple Meadow. Look for the long bright green chains before you reach the service road.

5)  Tillia cordata ‘Bicentennial’                Bicentennial Littleleaf Linden

  • This selection of the popular street tree is known for a dense and conical form.
  • Its moderate size makes Tillia cordata useful in areas where space is limited.
  • Littleleaf Linden is known for its sweetly-scented spring flowers. Tillia fruit are held below a stiff bract similar to that on a maple seed which acts like a “helicopter” as it falls.
  • A fine specimen can be seen at the intersection of Arboretum Drive and East Foster Island Road.

May Colors Appear Just in Time for Mother’s Day!

May 7th, 2016 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (May 2 - 15, 2016)

Selected cuttings from the Washington Park Arboretum
(May 2 – 15, 2016)

Happy Mother’s Day!

1)  Philadelphus coronarius

  • Native to southeastern Europe and Asia Minor, this shrub is located within the Sorbus Collection. It is perhaps the best-known species of mock orange in gardens because of its sweet smell. The fragrance of its flowers is pleasing out-of-doors, but may become too strong if the plants are numerous or near sitting room windows.
  • Philadelphus is a member of the plant family, Hydrangeaceae.

2)  Rhododendron   ‘Favor Major’

  • Located just west of parking lot #5, this hybrid is showing its yellowish-orange flowers.

3)  Rhododendron   ‘Ruby Hart’

  • Located within the Hybrid Bed, this shrub certainly has been given an appropriate cultivar name.

4)  Robinia x holdtii

  • A member of the plant family, Leguminosae, the genus Robinia contains about
    20 deciduous trees and shrubs confined to North America. The name Robinia
    commemorates Jean Robin, herbalist to Henry IV of France.
  • Specimen is located in the Legumes.

5)  Styrax obassia

  • A broadly columnar deciduous tree bearing elliptic dark green leaves and bell-
    shaped white flowers, S. obassia is native to northern China, Korea, and Japan.
  • This specimen is located along the upper trail near Rhododendron Glen.

“Story Time” at the Washington Park Arboretum

April 25th, 2016 by UWBG Horticulturist

The stories of people and plants are intricately intertwined.  The plants of the University of Washington Botanic Gardens have many stories to tell, and here are just a few to wet your whistle.  Explore our website at to look up and locate plants in the Arboretum and learn more of our stories.

Selected cuttings from the Washington Park Arboretum, April 18 - May 2, 2016

1)  Abies grandis – Grand Fir                “Fir Above It All”

  • This particular tree has witnessed the entire history of the Washington Park Arboretum.  It is almost certainly a remnant of the vegetation that existed before the site was logged circa 1896.  You can read more about this remarkable tree’s history on the March 2016 plant profile.

2)  Castenea dentata – American Chestnut
“A Blight to Remember”

  • Once upon a time in the eastern forests of North America, the mighty American Chestnut was a ubiquitous giant.  This tree could shape entire ecosystems, providing food and shelter to all manner of beasts and men.  It was said that the chestnuts would sometimes pile up so high you could scoop them up with a shovel.  This fast-growing timber tree provided wood that could be used to make almost anything a carpenter can build. Sadly, this tree has been decimated by “chestnut blight”, a fungus that quickly girdles and kills the tree.  The University of Washington Botanic Gardens is committed to the conservation of this tree and many other species that are threatened.

3)  Rhododendron ‘Lem’s Cameo’                “Halfdan Lem and the Rhodies of War”

  • Some of Halfdan Lem’s story was told to the Vancouver Rhododendron Society meeting of March 1993.  When World War II started, Mr. Fred Rose in England sent Lem seed and scions of many of his crosses and the resulting plants formed the nucleus of Lem’s breeding program.  By the mid-sixties, he had made over 2000 crosses and had about 50,000 seedlings.  One of his first introductions was “Lem’s Cameo”, an outstanding and popular variety.  Halfdan was reported to be quite a “colorful” character, and you can see some of his legacy in the Puget Sound Hybrid Garden.  Many other stories about Halfdan Lem may be found in the Journal of the American Rhododendron Society, which is available online.