August 6th, 2015 by UWBG Horticulturist
If this year’s hot and dry summer is a climate change omen for Seattle and the greater PNW, then here’s the tree of our future: Lagerstroemia spp and its many hybrids and cultivars. Commonly known as crapemyrtles, these trees are tolerant of hot and dry summers and offer appeal throughout the seasons. They have lustrous foliage and large colorful flowers in the growing season (spring and summer); in the dormant season (fall and winter), the foliage and bark provide interest.
‘Sioux’ is a National Arboretum Fauriei Hybrid crapemyrtle introduction from the 1950s that produces an abundance of large, bright pink flower clusters during summer. Its foliage is the darkest green of any crapemyrtle and turns to a handsome purple color in fall. The bark is tan in color and the twigs have a reddish color. See National Arboretum link below for more information on the Fauriei hybrids.
Common Name: Sioux Crape Myrtle
Location: Center for Urban Horticulture, west end of Douglas Greenhouse parking lot
Origin: National Arboretum Introduction. Name registered May 1, 1992.
Height and Spread: 12′-15′ tall; 8′-10′ wide. Multi-stemmed small tree, large shrub
Bloom Time: Summer, extended out as long as temperatures remain warm.
Specimen at CUH
July 12th, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (July 6 – 20, 2015)
1) Itea ilicifolia Holly-leaved Sweet Spire
- Native to western China
- Evergreen shrub growing up to 16 feet tall and 10 feet wide
- Bears fragrant racemes of greenish-white flowers in late summer and fall
- Located west of the Magnolia Collection near the south end of the Asiatic Maples
2) Lomatia myricoides Long-leaf Lomatia
- Native to New South Wales in southeastern Australia
- One of the hardier members of the Proteaceae
- Honey-scented white flowers are much visited by bees in summer
- Located across Arboretum Drive from the New Zealand Focal Forest
3) Pterocarya stenoptera Chinese Wingnut
- Native to China
- Deciduous tree to 70 feet or greater, with a trunk diameter as large as 8 feet
- Located west of Azalea Way, north of Loderi Valley
4) Quercus vacciniifolia Huckleberry Oak
- Native to western North America, mountains of the Sierra Nevada and southern Cascade Range
- Leaves and acorns are an important food source for birds and mammals within its native range.
- Located atop the rockery at the east end of the trail above the Gateway to Chile
5) Rehderodendron macrocarpum Mu gua hong
- Native to Mt. Emei, Sichuan Province, China
- Small deciduous tree 20 to 30 feet tall, related to Styrax
- Located east of Azalea Way on the north end of the Rhododendron Hybrid bed
June 15th, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (June 8 – 21, 2015)
1) Cornus controversa Giant Dogwood
- A rounded deciduous tree bearing spreading, tiered branches and alternate, elliptic leaves, C. controversa can potentially reach 40 feet in height. White flowers are borne in large, flattened cymes in early summer. Following the flowers, masses of deep red fruit develop, changing to blue-black.
- Native to China, the Himalayas and Japan, C. controversa is less cold tolerant than our native dogwoods. This specimen is located along Azalea Way near the Hybrid Bed.
2) Kalmia latifolila Mountain Laurel
- A dense, bushy shrub with glossy, dark green leaves and large corymbs of cup-shaped flowers, Kalmia latifolia is native to North America. Thought by many to be our country’s most beautiful flowering shrub, it is the state flower of both Connecticut and Pennsylvania.
- This specimen is located along the lower trail, near Rhododendron Glen.
3) Quercus robur ‘Concordia’ Golden English Oak
- A standout specimen amongst the late spring flush of green, Q. robur ‘Concordia’ offers us bright yellow young foliage which will eventually turn color in the fall.
- It is located on the east side of Azalea Way near the Woodland Garden.
4) Pterocarya stenoptera Chinese Wingnut
- A large spreading tree with long pinnate leaves and winged green fruit produced in pendent spikes up to 12 inches in length. Wingnuts are a member of the plant family Juglandaceae.
- This specimen is located at the south end of the nut flats, just west of Azalea Way.
5) Staphylea pinnata Bladdernut
- A deciduous shrub up to 15 feet high, S. pinnata is known for its curious bladder-like fruits in late spring and early summer. This specimen is located amongst the True Ashes, west of Azalea Way.
June 12th, 2015 by UWBG Horticulturist
An Osprey nesting pole was installed yesterday in Union Bay Natural Area (UBNA). Located near Carp pond in the SE corner of UBNA loop trail. UW Athletic Dept funded the project when it was realized Osprey were being attracted to nesting in ball fields’ lighting across the way. Hopefully now, people will be safe from falling branches and Osprey will have more appropriate digs to settle into.
Jim Kaiser, consulting wildlife biologist and owner of Osprey Solutions, was hired to do the install. Jim has installed over 300 Osprey nesting poles in the PNW. He is one of the most knowledgeable biologists on Osprey and has quite a fascinating and experienced repertoire in creating new homes for them.
For more information on Osprey and their nests, please visit:
Osprey fact sheet
Attaching nesting platform to pole
Erecting Nesting Pole
Looking south along UBNA loop trail
May 15th, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (May 11-24, 2015)
1) Cytisus x praecox ’Luteus’ Warminster Broom
- This broom is a hybrid of C. multiflorus and C. purgans and is located on Arboretum Drive in the Legume Collection.
- Many of the brooms are blooming now or soon to bloom, including the pineapple broom, Argyrocytisus battandieri, whose fragrance earned it its common name.
2) Erica arborea var. alpina Tree Heath
- While non-alpine tree heath can reach heights in excess of 20 feet, the alpine variety is the “short” one, reaching only 10 to 15 feet.
- Alpine tree heath has white flowers versus light-gray, and the scent is reminiscent of honey.
3) Hydrangea luteovenosa Sweet Hydrangea
- In full bloom now, this semi-trailing Hydrangea is located on the Ridgetop Trail in Rhododendron Glen.
- Though widely distributed in western Japan, this species of Hydrangea is critically endangered in Korea.
4) Rhododendron ‘Snow Lady’ x Rhododendron degronianum ssp yakushimanum
- Hybrids are often created to blend two or more outstanding traits from two separate taxa into one single plant, e.g. flower color and leaf indumentum.
- There are several areas in the Washington Park Arboretum, including Azalea Way, Loderi Valley, Rhododendron Glen and the Puget Sound Rhododendron Hybridizers bed, showcasing many hundreds of hybrids of Rhododendron.
5) Syringa reflexa Nodding Lilac
- The buds of Syringa reflexa start out a rosy–red before opening to pink and eventually fading to almost white.
- The specific epithet “reflexa” refers to the nodding habit of the flower heads.
- Lilacs are located throughout the Washington Park Arboretum, though many are found just south of the Woodland Garden along Azalea Way.
May 1st, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (April 27 – May 10, 2015)
Opening Day crew races through the Montlake Cut, and the 1936 USA Olympic gold in rowing may never have happened without these following trees:
1) Thuja plicata Western Red Cedar
- UW’s world-renowned boat maker, George Pocock followed the lead of Native Americans and used this Pacific Northwest giant for the hulls of his Pocock Classics.
- The skin is made from a single plank of 3/32″ thick cedar and offers a combination of stiffness and springiness that eliminates the need for the extra weight of a hull.
2) Pinus lambertiana Sugar Pine
- Keels of Pocock’s boats were made from this soft, even-grained Oregon native.
- Sugar pine has very low shrinkage when it dries, so hull warping and cracking was kept to a minimum with this choice wood.
3) Xanthocyparis nootkatensis Alaska Yellow Cedar
- Cheeks (two lowest timbers at the head rails) and washboards (thin planks fastened to the side to keep out water) were made from this honey-colored wood.
- Pocock was especially fond of the way Xanthocyparis aged with Thuja plicata.
4) Picea sitchensis Sitka Spruce
- Hand-carved seats and gunnels (uppermost plank in a hull) were made from these giants from Vancouver, BC.
5) Picea engelmannii Engelman Spruce
- Oars used in rowing competitions are made from Engelman Spruce.
- The oar consists of three bonded pieces made from one single plank of Engelman spruce split to make mirror-imaged sides, and another piece is cut for the center.
Resources: http://www.pocockclassic.org, http://shipwrightjournal.blogspot.com
April 19th, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (April 13 – 26, 2015)
1) Acer cissifolium Vine-leaf Maple
- A three-leaf maple native to Japan.
- The extraordinary racemes of tiny flowers give the tree a cloud-like appearance.
- Located in the Asiatic Maple Collection.
2) Acer rubrum Red Maple
- This popular street tree is native to eastern North America.
- On this sample the petals have fallen, leaving the elongating peduncles and their tiny, immature samaras.
- Located in grid 3-5E on Arboretum Drive.
3) Cornus florida Flowering Dogwood
- Named for its showy bracts.
- Native to the eastern United States.
- These cuttings are from ‘Royal Red’ near the south end of Azalea Way and from an unlabeled white cultivar near the north end.
4) Cornus nuttallii Pacific Dogwood
- A west coast native named for Thomas Nuttall– a British botanist and explorer.
- Natural seedlings are scattered throughout the Arboretum.
- This is the provincial “flower” and floral emblem of British Columbia.
5) Cornus nuttallii x florida ‘Eddie’s White Wonder’
- So named because it was one of a few survivors of a flood at Henry Eddie’s nursery near Vancouver, B.C.
- It is a hybrid of Cornus nuttallii and C. florida.
- Several specimens are growing along Azalea Way.
April 5th, 2015 by UWBG Horticulturist
Selected cuttings from the Viburnum Collection at the Washington Park Arboretum (3/30/15 – 4/13/15)
Our Viburnum Collection is recognized as one of the top three national collections. Our taxonomic display currently is home to over 100 different kinds and 330 living specimens.
[Description references: “Viburnums — Shrubs for Every Season” by Michael Dirr.]
Here are a few samples of this diverse and ornamental shrub.
1) Viburnum carlesii var. bitchiuense Bitchu Viburnum
- Wonderfully fragrant flowers in early spring.
- Closely allied to V. carlesii. Botanists still debate whether to “split” or “lump”.
- Located across from the Graham Visitor Center in full flower. Grid: 40-3E
2) Viburnum macrocephalum Chinese Snowball Viburnum
- 6’-10’ rounded shrub.
- Known for 3″ – 8″ wide, hemispherical cymes, hence the name “Snowball”.
- Located along maintenance facility mixed-shrub border fence. Grid: 43-5E
3) Viburnum propinquum
- Large evergreen shrub with glossy three-veined leaves.
- Known to be tender in cold Pacific Northwest winters.
- Located in the Rhododendron Glen parking lot landscape. Grid: 12-8E
4) Viburnum x rhytidophylloides ‘Alleghany’ Lantanaphyllum Viburnum
- National Arboretum introduction in 1958.
- Handsome dense evergreen shrub with abundant inflorescences.
- Located in Viburnum Collection. Grid: 25-5W
5) Viburnum utile Service Viburnum
- Rare in commerce, but important evergreen species for breeding.
- Dirr doesn’t think it has much ornamental value. I (David Zuckerman) disagree.
- Located in Viburnum Collection. Grid: 26-4W
March 6th, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (March 2 – 16, 2015)
1) Acer triflorum Three Flower Maple
- A small, slow-growing deciduous tree 20’ to 45’ where it is native in Manchuria and Korea. An excellent landscape tree boasting light grey vertically-furrowed bark and vivid red and orange fall color. The name refers to its flowers, which are borne in clusters of three.
- Discovered by noted plant explorer, Ernest H. Wilson in 1917.
- Located in the Asiatic Maples Collection. Grid: 26-B
2) Corylopsis sinensis var. calverescens Winter Hazel
- A medium-sized deciduous, broadly vase-shaped shrub in the Witch Hazel family.
- Bean describes it as flowering in April.
- Located in the Witt Winter Garden. Grid: 34-1E
3) Magnolia x loebneri‘Ballerina’ Magnolia
- This small deciduous tree is a hybrid between M. x loebneri ‘Spring Snow’ and M. stellata ‘Water Lilly’.
- The specific epithet honors Max Loebner, a German horticulturist, who made the first cross of this hybrid in the early 1900s.
- Located on the west side of Arboretum Drive in the Magnolias Collection. Grid: 28-4E
4) Rhododendron thomsonii ssp. thomsonii ‘Glory of Penjerrick’
- A large evergreen shrub with a rounded crown noted for very early bloom time.
- An early hybrid used as parent for many subsequent Rhododendron hybrids.
- Located west of Azalea Way, north of the path to the Wilcox foot bridge.
5) Sorbus caloneura Whitebeam
- This small upright deciduous tree is native to southeastern China and Tibet.
- The leaves are heavily pleated, giving them the appearance of beech leaves.
- Fruit are extremely hard and persist well into winter.
- Located at the south end of the Sorbus Collection. Grid: 20-4E
February 22nd, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (February 17 – March 1, 2015)
1) Camellia japonica ‘Nina Avery’
- Due to this year’s mild winter thus far, many plants here have begun flowering much earlier than normal, and Camellias are certainly no exception. Many specimens can be seen in bloom along Arboretum Drive near Rhododendron Glen.
2) Camellia x williamsii ‘Mary Christian’
- Soon after C. saluenensis began to flower it was crossed with C. japonica, notably by J. C. Williams at Caerhays. One of the first plants raised there was named ‘Mary Christian’.
- Trumpet-shaped, single, carmine-pink flowers are currently on display.
3) Larix kaempferi Japanese Larch
- The needle-shaped leaves of L. kaempferi are just beginning to emerge.
- Native to Japan and able to reach 80-100 feet in height, this species was introduced by John Gould Veitch in 1861.
- A member of the family Pinaceae, this specimen is located in the Pinetum near the Stone Bridge.
4) Magnolia ‘Royal Crown’
- This is a popular clone with dark red-to-violet flowers, white on the inside. It was first hybridized by D. Todd Gresham of Santa Cruz, California, who sometimes referred to plants of his cross as the “svelte brunettes” because of the dark color and sleek form of the flowers.
- Located along Arboretum Drive within the Magnolias.
5) Symphoricarpos orbiculatus Coralberry
- A dense, bushy shrub with ornamental fruit currently on display.
- Native to the United States.
- Specimen located within the Viburnums.