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 6th, 2014 by UWBG Communication Staff
By John A. Wott, Director Emeritus
This photograph, taken on April 4, 1950, is located somewhere to the left of the location of the Lookout Shelter. It points southwest. Originally, the hillside held a large collection of Ceanothus, but they were killed during severe winters and never replaced. If one looks closely you can see “tracks” on Azalea Way, the outline of Arboretum Creek, and East Lake Washington Boulevard. It appears there is one house on the lower level of Interlaken Boulevard East, and of course, many homes on the slopes of Capitol Hill are easily seen.
Looking southwest to Lake Washington Blvd and Capitol Hill from Ceanothus area by the Lookout Shelter
The kiosk at the intersection of East Lake Washington Boulevard and Interlaken Boulevard East is visible. Note how open the area is with small collection plantings and few towering native trees. This was taken before the construction of the Japanese Garden.
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 24th, 2014 by UWBG Horticulturist
Earth Day 2014
On Saturday, April 12th, over 220 people joined together at Washington Park Arboretum to celebrate Earth Day with SCA! The day began with Seattle mayor Ed Murray, SCA founder Liz Putnam, current SCA student Diana Furukawa, and others celebrating the day and imploring volunteers to consider the effects of climate change and to take action in their communities. SCA youth lead eight volunteer groups around the park. Together volunteers accomplished the following:
- 14,044 sq ft invasive plants removed
- 40 cubic yds mulch spread
- 205ft trail maintained (graveled)
- 94 plants potted
Check out amazing photos from the day here!
Check out the project map:
Text and photos contributed by SCA
April 24th, 2014 by UWBG Horticulturist
A mature western hemlock, Tsuga heterophylla, is scheduled for removal on Wed, April 30. It is located in Rhododendron Glen, north of the Glen pond.
- Fungal conks seen growing on the trunk is an indicator that a rot inducing pathogen is present.
- Its hazard potential is great due to extensive internal decay.
- A wild-life snag will be left in place.
Each tree requires evaluation to determine the best course of action for the site.
Conks growing on hemlock trunk
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.
April 19th, 2014 by Catherine Nelson, Adult Tours Program Assistant
Rhododendron macabeanum is one of the finest big leaved Rhododendron species and has received the Royal Horticultural Society’s Award Of Garden Merit. It has large yellow/white flowers often blotched purple inside with an interesting bright pink stigma. The leaves are a dark glossy green and about 1′ in length with a light colored indumentum on the underside. It also bears a nice silvery young leaf and bright red bud scales.
Native to India at high elevations, this plant was introduced to the West in 1927. We have a wonderful specimen in the arboretum. It is blooming right now and is located between the SE corner of Loderi Vally and the Magnolia Collection. Our April Free Weekend Walks on Sundays at 1:00 pm will continue to feature this and other amazing Rhododendrons in the UWBG collection.
April 6th, 2014 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (4/1/14 – 4/14/14)
1) Berberis x lologensis
- A natural hybrid of B. darwinii and B. linearifolia originally found near Lake Lolog, Argentina in 1927
- If you can get past the thorns, enjoy the rich, spicy fragrance.
- Located in grid 14-6E near Arboretum Drive.
2) Acer tegmentosum ‘Joe Witt’
- This striped-bark maple is named for former Arboretum Director Joseph Witt.
- Located in the Witt Winter Garden and on Arboretum Drive in the Peonies.
3) Magnolia salicifolia ‘Else Frye’
- Selected by Joe Witt for its larger flowers and named for the wife of T.C. Frye.
- See Arboretum Bulletin Summer 1961, Summer 1962, and Winter 1962 for articles about this tree and the Fryes.
- The original tree is in the Magnolia Collection, grid 26-2E.
4) Magnolia x kewensis ‘Wada’s Memory’
- Part of a collection of plants purchased from Koichiro Wada in Japan in 1940.
- Selected by Arboretum Director Brian Mulligan for its unusually large flowers.
- The original tree is in grid 11-6E in the Hydrangeas.
5) Quercus suber (Cork Oak)”
Close-up photo of Quercus suber (Cork Oak)
- Evergreen oak native to southern Europe. A tree of incalculable social value, it produces the cork of
- Located in the Rock Roses on Arboretum Drive.
- This cutting includes the distinctive acorns – extremely rare in the Pacific Northwest.
April 5th, 2014 by Catherine Nelson, Adult Tours Program Assistant
The Rhododendron occidentale is one of two NW native Rhododendron species (the other being our Washington State Flower, Rhododendron macrophyllum).
Commonly called Western Azalea or Honeysuckle Shrub, it is found along the Pacific Coast from lower Washington to central California. This species shrub is tolerant of wet soils and can be found in wetlands and along creeks in its native environment.
These Azaleas can grow to 15 ft. in height and do well in our Seattle climate when provided some shade, though they are not drought tolerant in summers. They are prized for their beautifully colored pink/white/yellow flowers, which are extremely fragrant this time of year.
John Muir encountered the shrub in the Yosemite region & said of it, “It is very showy & fragrant, & everybody must like it not only for itself but for the shady alders & willows, ferny meadows, & living water associated with it.”
Our UW Botanic Gardens’ Free Weekends Walks for the month of April will feature Rhododendron species and cultivars during their their peak bloom time. Please join us any Sunday at 1:00pm at the Graham Visitors Center to learn more.