September 14th, 2014 by UWBG Horticulturist
The State of the Arboretum
Selected cuttings from the Washington Park Arboretum (September 8 – 21, 2014)
1) Liriodendron tulipifera Tulip Tree
- The state tree of Indiana.
- The Western Hemisphere representative of the two-species genus Liriodendron, and the tallest eastern hardwood.
2) Pinus resinosa Red Pine
- The state tree of Minnesota.
- It is a long-lived tree, reaching a maximum age of about 500 years.
- The wood is commercially valuable in forestry for timber and paper pulp, and the tree is also used for landscaping.
3) Pinus strobus Eastern White Pine
- The state tree of Michigan.
- Eastern white pine forests originally covered much of northeastern North America. Only one percent of the old-growth forests remain after the extensive logging operations that existed from the 18th century into the early 20th century.
- This tree is known to the Native American Haudenosaunee (Iroquois Nation) as the “Tree of Peace”.
4) Sequoia sempervirens Coast Redwood
- The state tree of California.
- These trees are among the oldest living things on Earth.
- Before commercial logging and clearing began by the 1850s, this massive tree occurred along much of coastal California and the southwestern corner of coastal Oregon.
5) Tsuga hetrophylla Western Hemlock
- The state tree of Washington.
- Tsuga heterophylla is an integral component of Pacific Northwest forests west of the Coast Ranges, where it is a climax species. It is also an important timber tree throughout the region, along with many of its large coniferous associates.
August 17th, 2014 by Kathleen DeMaria, Arboretum Gardener
Selected cuttings from the Washington Park Arboretum (August 11 – 24, 2014)
1) Poliothyrsis sinensis
- A rare and very attractive small flowering tree of upright, open habit.
- Originally brought from China to the Arnold Arboretum by E.H. Wilson.
- Big 6-8” mildly fragrant, creamy flower clusters (corymbose panicles) make a significant contribution to the August-September garden.
- Located in grid 30-3E, near the south entrance to the Woodland Garden along Arboretum Drive.
2) Daphniphyllum macropodum
- This dioecious plant (translation = “of two houses”) needs plants of both sexes to seed.
- Our largest grouping sits in grid 7-2E. This area was recently renovated for the New Zealand Garden construction, allowing more light and air to these plants.
- Purplish-red petioles, copious berries and leaves arranged in tight spirals make this one of the most asked-about plants in the Washington Park Arboretum.
3) Veronica salicifolia (Hebe salicifolia)
- Is it a Hebe? Is it a Veronica? Just wait and it might change again!
- Large, spear-shaped, white flowers populate this New Zealand native in late summer.
- Salicifolia = “leaf like a Salix (willow)”, hence the common name willow-leaved hebe.
4) Buplerum fruitcosum
- This evergreen shrub in the carrot family has striking leathery blue-green foliage.
- Long-lasting, umbels of greenish-yellow flowers bloom in late spring/early summer.
- Flowers are highly attractive to a number of predatory insects that feed on aphids and other garden pests.
5) Argyrocytisus battandieri
- Commonly called Pineapple Broom, this pea-family plant produces yellow flowers atop blue-gray foliage.
- Native to Morocco, this plant grows best in full sun and well-drained soil.
- Located along the west side of Arboretum Drive in grid 16-5E.
August 4th, 2014 by UWBG Arborist, Chris Watson
Selected cuttings from the Washington Park Arboretum (July 21 – August 8, 2014)
1) Houpu Magnolia (Magnolia officinalis var. biloba)
- Unique bi-lobed leaf 8-12″ in length
- 4-8″ seed pods on display in late summer
- Located in grid 27-1W in the Rhododendron hybrid bed
2) Sargent Magnolia (Magnolia sargentiana var. robusta)
- Bears large pink flowers in spring
- Large, pinkish-red fruit appear in late summer and fall
- Located in grid 13-7E in Rhododendron Glen
3) Rehder Tree (Rehderodendron macrocarpum)
- White flowers appear in spring
- 3-4″ seed pods weigh down branches in late summer
- Located in grid 13-6E and elsewhere throughout the Washington Park Arboretum
4) Himalayan Stachyurus (Stachyurus himilaicus)
- Deciduous or semi-evergreen shrub to height of 10’
- Displays clusters of flowers in early spring
- Located in grid 25-1W
5) Yunnan Stachyurus (Stachyurus yunnanensis)
- Small evergreen shrub to height of 6’
- Chains of white flowers appear in spring
- Located in grid 25-1W
July 12th, 2014 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (July 7 – 20, 2014)
1) White Ash (Fraxinus americana)
- Tough, plentiful, and easily bent into curves, Ash is used in tennis racquets, billiard cues, skis, and baseball bats.
- White Ash is native to eastern and central North America.
- This cutting is from the cultivar ‘Rose Hill’, located in grid 47-3E near the Lagoons.
2) Common Box (Buxus sempervirens)
- Used for crocquet balls because of its hardness.
- Native to Europe, northern Africa and western Asia.
- The cultivar here is ‘Argentea’ from grid 5-B in our Boxwood Collection.
3) American Hop Hornbeam (Ostrya virginiana)
- The first ice hockey sticks were made from the dense wood of this small tree in the mid-19th century until the 1930s by the Mi’kmaq people of Nova Scotia.
- Ostrya virginiana is native to eastern North America.
- The Arboretum has two trees in grids 19-3W and 24-4W.
Close-up photo of Persimmon flowers
4) Persimmon (Diospyros virginiana)
- The “woods” of golf (drivers, not Tiger’s) were typically made from this American member of the ebony family from which it inherits its extreme density.
- Persimmon is most common in the southeastern United States.
- In the Arboretum, they are in grids 12-1W and 12-2W, north of the Boyer Street parking lot.
5) Sugar Maple (Acer saccharum)
- Commonly called “rock” maple by those who value its hardness and smooth grain.
- This native of eastern North America provides wood for bowling alleys, bowling pins, basketball courts, and baseball bats.
- The Arboretum has several cultivars in various locations.
June 29th, 2014 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (June 23 – July 6, 2014)
1) Erhetia dicksonii
Close up photo of Ehretia dicksonii inflorescence
- Ornamental tree from Asia with corky bark and fragrant white terminal cymes.
- Located along path heading up to Rhododendron Glen from Azalea Way, grid 15-1E.
- Go to link below for thorough description and uses.
2) Holodiscus discolor (Ocean Spray)
- My favorite summer flowering Pacific Northwest native deciduous shrub.
- In full flowering, cascading glory now throughout our native matrix.
3) Hypericum henryi ssp. uraloides
- The really big Azalea Way flower show may be over, but now it’s Hypericum time.
- This shrubby St. John’s wort is a huge attractant of many kinds of bees.
- Located in east-side bed J, midway down Azalea Way, grid 20-1W.
4) Illicium henryi (Henry Anise Tree)
Close up photo of Toona sinensis leaves and inflorescence
- A handsome evergreen woodland shrub or small tree from China.
- Waxy, bright rose-colored flowers. Leaves and star-shaped fruit give off a scent of anise when crushed.
- Located along forested Ridge Trail within the Asiatic Maple section, grid 25-1E.
5) Toona sinensis (Chinese Cedar)
- You can Toona piano, but you can’t Toona fish . . . or in this case, a tree.
- Deciduous tree from eastern and southeastern Asia with pinnately compound leaves and white flowering panicles in summer.
- Located in north Pinetum, grids 44 and 45-6W. For cultural, medicinal and commercial (timber) importance, go to link http://en.wikipedia.org/wiki/Toona_sinensis.
June 15th, 2014 by UWBG Horticulturist
1) Hydrangea macrophylla ‘Madame Emile Mouillere’
- A blizzard white beauty all summer, long considered the best white mop head.
- A charming companion to evergreen shrubs.
- A beautiful 70-year old specimen graces the Hydrangea Collection along the Arboretum Drive.
2) Leucothoe davisiae (Sierra Laurel)
- Native to the mountains of northern California and southern Oregon.
- One of 4,000 species in the Ericaceae family.
- A 20-year old specimen can be found in the Rhododendron Glen.
3) Rosa moschata ‘Plena’ (Double Musk Rose)
- Cultivated in European and American gardens for centuries.
- Grown for its strong, clove musk fragrance and abundant alabaster white flowers.
- A 65-year old specimen is flourishing by the entrance to the horticulture headquarters.
4) Stewartia pseudocamellia var. koreana (Korean Stewartia)
- Native to Japan and Korea, this tree has garnered the Royal Horticulture Society’s Award of Garden Merit.
- The flowers are white with orange anthers, shaped like those of the related camellia.
- A graceful 64-year old specimen is growing beautifully at the south end of Arboretum Drive.
5) Philadelphus lewisii (Lewis’ Mock Orange)
May 29th, 2014 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (May 27 – June 8, 2014)
1) Crataegus crus-galli Cockspur Hawthorn
- Native to eastern North America, this small deciduous tree has a pleasant habit and is now showing off its small white flowers, but don’t get too close! The rigid thorns can be up to three inches long.
- Hawthorns are classified within the plant family Rosaceae, and are allied to Cotoneaster, Mespilus, and Pyracantha.
- This specimen is located on the east side of Lake Washington Boulevard, just north of the Boyer Parking Lot.
2) Deutzia x hybrida ‘Magicien’
- Named after Johann van der Deutz, a friend of Thunberg in 18th century Amsterdam, Deutzia contains some of the most beautiful shrubs currently in flower. It is a member of the family Hydrangeaceae.
- This specimen is located near the east side of our field nursery, along the Broadmoor fence.
3) Kalmia latifolia Mountain Laurel
- Native to eastern North America, Kalmias are a small group of shrubs within the family Ericaceae. They were named by Linnaeus in honor of Peter Kalm, one of his pupils. The Arnold Arboretum near Boston boasts a great hedge of K. latifolia that are over 200 yards long.
- These cuttings were taken from specimens on Arboretum Drive near the Woodland Garden.
4) Ostrya carpinifolia European Hop Hornbeam
- A member of the family Betulaceae, the genus Ostrya contains about ten closely related species native to various parts of the northern hemisphere. O. carpinifolia is native to southern Europe. Female catkins develop into hop-like fruits in the summer.
- This specimen is located within our Hornbeam Collection near the terminus of Foster Island Road.
5) Viburnum dilatatum Linden Viburnum
- An upright, deciduous shrub native to Japan and China, V. dilatatum is displaying its small flowers borne in domed, terminal corymbs, similar to those of ‘lacecap’ hydrangeas.
- This cutting was taken from a specimen within our Viburnum Collection, just west of the “True Ashes”.
May 18th, 2014 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (May 12 – May 25, 2014)
“That’s Ancient History”
1) Cedrus libani (Cedar of Lebanon)
- The Cedar of Lebanon has been prized for its high quality timber, oils and resins for thousands of years.
- It was used by the Phoenicians and Egyptians and was mentioned in the Epic of Gilgamesh.
- Because of its significance, the word “cedar” is mentioned 75 times in the Bible, and played a pivotal role in the cementing of the Phoenician-Hebrew relationship.
2) Helleborus niger (Black Hellebore, Christmas Rose)
- Helleborus niger is commonly called the Christmas rose due to an old legend that it sprouted in the snow from the tears of a young girl who had no gift to give the Christ child in Bethlehem.
- During the Siege of Kirrha in 585 B.C., Hellebore was reportedly used by the Greek besiegers to poison the city’s water supply. The defenders were subsequently so weakened by diarrhea that they were unable to defend the city from assault.
3) Laurus nobilis (Bay Laurel, Sweet Bay)
- Bay Laurel was used to fashion the laurel wreath of ancient Greece, a symbol of highest status. A wreath of bay laurels was given as the prize at the Pythian Games because the games were in honor of Apollo, and the Laurel was one of his symbols.
- In the Bible, the Laurel is often an emblem of prosperity and fame. In Christian tradition, it symbolizes the resurrection of Christ.
4) Rhododendron ponticum
- Xenophon described the odd behavior of Greek soldiers after having consumed honey in a village surrounded by Rhododendron ponticum during the March of the Ten Thousand in 401 B.C.
- Pompey’s soldiers reportedly suffered lethal casualties following the consumption of honey made from rhododendron deliberately left behind by Pontic forces in 67 B.C. during the Third Mithridatic War. Later, it was recognized that honey resulting from these plants has a slightly hallucinogenic and laxative effect.
5) Taxus baccata (English or European Yew)
- One of the world’s oldest surviving wooden artifacts is a Clactonian yew spear head, found in 1911 in Essex, U.K. It is estimated to be about 450,000 years old.
- A passage by Caesar narrates that Catuvolcus, chief of the Eburones poisoned himself with yew rather than submit to Rome (Gallic Wars 6:31).
May 3rd, 2014 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (April 28 – May 11, 2014)
1) Rhododendron spp. Azalea
- Azaleas are in the genus Rhododendron, with evergreen azaleas in the subgenus Tsutsusi and deciduous azaleas in the subgenus Pentanthera.
- The Olmstead Brothers originally planned for 11,000 azaleas to be planted along Azalea Way. More than 3,100 have been planted and over 2,000 remain.
- Azalea Way contains 21 species of azalea and more than 200 hybrids.
2) Tsuga heterophylla Western Hemlock
- Our native western hemlocks are currently laden with new female cones which are deep purple when immature.
- Currently, a scientific experiment is being conducted as a collaboration between the Washington Park Arboretum and the University of Massachusetts, using the collection of T. heterophylla and T. canadensis.
- We are studying the predator/prey relationships among the hemlock Wooly Adelgid, eastern and western hemlocks, and the predator species that prey on the Adelgid.
3) Syringa oblata var. dilatata, S. patula Lilac
Close-up photo of newly-forming female cone on Larix decidua
- Our Lilac Collection contains more than 14 species along with several more hybrids.
- Our primary lilac display is on Azalea Way, just south of the Woodland Garden.
4) Larix decidua, L. kaempferi Larch
- Now is a great time to admire many conifers for their display of young and old cones on the same branch.
5) Rhododendron ‘El Camino’ Halfdan Lem hybrid
- Our Puget Sound Rhododendron hybrid bed is located on Azalea Way south of our Lilac Collection.
- This bed contains plants from local hybridizers dating back to the early 1940s.
April 20th, 2014 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (April 15 – 28, 2014)
1) Melicytus angustifolius
- This southern hemisphere Violaceae relative thrives in rocky places in mountains or on coasts, or in evergreen forests.
- Is ‘dioecious’ or ‘of two houses’ in Greek translation; male and female flowers are present on separate plants.
2) Erica arborea var. alpina
- Found along the southern end of Arboretum Drive, this is one of the older collections in the Washington Park Arboretum, dating back to 1947.
- This form, var. alpina, is a smaller shrub, very hardy, and with brighter green foliage, making an imposing highlight among smaller heaths and heathers.
3) Poncirus trifoliata (syn. Citrus trifoliata)
- Bitter, non-edible yellow fruits that resemble a small orange
- Two large specimens in the Arboretum found in grid 8-1W and 12-B, north of the large parking lot off of Lake Washington Bouvelard.
4) Viburnum carlesii var. bitchiuense
- This spicy smelling Viburnum is the intoxicating fragrance you’ll be hit with the moment you walk out the front door of the Graham Visitor’s Center.
- Listed on the IUCN Red List of Threatened Plants in 1997, our cultivation of this plant helps to preserve a propagation source for future plants.
5) Phyllocladus alpinus
- This New Zealand conifer can photosynthesize through highly modified, leaf-like shoots called phylloclades as well as through leaves.
- The newly-formed seed cones are berry-like, with a fleshy white aril.
- Male and female flowers are separate, but borne on the same plant.