February 14th, 2016 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum,
February 8 – 21, 2015
1) Pinus greggii
- This three-needle pine from northeastern Mexico is closely akin to P. patula but less ornamental. Its oval-conical cone clusters stay closed on the branch for several years. This specimen and the others described here can be found within Crabapple Meadow, along the east side of Arboretum Drive.
2) Pinus jeffreyi
- Native mainly of California in the Sierra Nevada and Siskiyous, this lofty tree is said to grow to 200 feet in the wild. P. jeffreyi is closely allied to P. ponderosa and at one time, it was normal to regard it as a variety of that species. Its three-needle bundles are said to give off a fruity scent when bruised.
Close-up of Pinus greggii cones
3) Pinus montezumae var. lindleyi
- This five-needle pine is native to southern and central Mexico at subtropical and cool temperate altitudes, with its best development at 7,000 to 8,000 ft. Its flexible, pendulous leaves (growing to 14 inches or longer) along with its broad, dome-shaped crown give it a distinct look.
4) Pinus pinaster
- Commonly known as the Maritime Pine, this specimen is native to southwestern Europe and north Africa. The glossy green leaves of this pine are the largest and stoutest of all two-needle pines, and it is said to be one of the best for light sandy soils. As its common name implies, it thrives in coastal maritime localities.
5) Pinus strobus ‘Fastigiata’
- A native of eastern North America, P. strobus has proven to be a valuable timber tree and one of the richest assets of our country. Its bluish-green five-needle clusters are three to five inches long, with lines of white stomata on the inner sides. Once again, all of these specimens listed here can be found within Crabapple Meadow, along the east side of Arboretum Drive.
January 31st, 2016 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum
(January 25 – February 7, 2016)
1) Oemleria cerasiformis Indian Plum
- The Indian Plum adheres to Benjamin Franklin’s advice in Poor Richards Almanac: “Early to bed, early to rise. . . .” This shrub goes to sleep early, beginning to slowly defoliate in late summer. However, it is one of the first to leaf out, and flowers early in the spring. It can be found throughout the Arboretum, and is just beginning to awaken.
2) Ophiopogon planiscapus ‘Nigrescens’ Black Mondo Grass
3) Magnolia × soulangeana Saucer Magnolia
- The Saucer Magnolia wraps its flower buds in a fuzzy blanket for its winter nap. As winter draws to a close and spring approaches, these buds will swell and open into a glorious pink and white show. You can find this and many other specimens of this wonderful genus in our nationally-recognized Magnolia Collection (http://depts.washington.edu/uwbg/gardens/wpa/collections.php).
4) Polystichum munitum Western Sword Fern
- The Western Sword Fern spends its winter in a tightly coiled bunch. As they unfurl in spring, these are called fiddleheads, as they resemble the curled ornamentation (called a scroll) on the end of a stringed instrument, such as a violin. Fiddleheads also just happens to be the name of the UW Botanic Gardens’ Nature Preschool Program (http://depts.washington.edu/uwbg/education/Youth/nature_preschool.shtml).
5) Tsuga heterophylla Western Hemlock
- Not all the plants in the Arboretum are providing shade for Little Nemo in Slumberland. Some plants, such as conifers like the Western Hemlock, do not go to sleep during the winter. As long as it is not too cold, they will happily photosynthesize, converting water and air into sugar.
January 16th, 2016 by UWBG Horticulturist
Selected cuttings from the Witt Winter Garden at the Washington Park Arboretum (January 11-24, 2016)
Witt Winter Garden
1) Cornus sanguinea ‘Midwinter Fire’
Midwinter Fire Dogwood
- Though the species normally has red twigs and purple fall color, this outstanding cultivar has golden-yellow fall color followed by red-blushed, yellow twigs.
- This dogwood is native to northern Europe into northwestern Asia.
- Full sun is required to obtain the best winter stem color and this dogwood will slowly colonize an area via suckers from its shallow roots unless controlled.
2) Corylus maxima ‘Atropurpurea Superba’ Purple Giant Filbert
- This excellent selection of the Giant Filbert produces long purple catkins in winter followed by large purple-red leaves in spring.
- From what we have observed in the Witt Winter Garden, this specimen is resistant to eastern filbert twig blight, caused by the fungus Anisogramma anomala.
3) Daphne bholua ‘Jacqueline Postill’ Lokta, Paper Daphne
- The specific epithet “bholua” comes from “bhulu swa”, the Nepalese name for the species.
- Despite having a native range to 12,000 feet in the Himalayas, this species of Daphne is just as hardy in Seattle and requires a protected placement in the garden.
4) Hamamelis x intermedia ‘Winter Beauty’ Winter Beauty Witch Hazel
- The north end of the Witt Winter Garden contains many species and cultivars of witch hazel.
- Witch hazel flowers range from sulfur-yellow to carmine-red, while their fragrance can be absent, lightly floral or an intense citrus.
5) Sarcococca hookeriana var. digyna Sweet Box
- Sweet box is an often overlooked element of the Witt Winter Garden due to the diminutive size of its flowers, though no one can miss their intense fragrance.
- Perfectly comfortable in dry shade, Sweet Box is an excellent choice for under-planting taller shrubs or small trees such as Hamamelis.
December 22nd, 2015 by UWBG Horticulturist
Boughs used as winter decoration are often from plants in the genus Ilex. Many Ilex, or holly species are dioecious, meaning that male and female reproductive organs are separated on individual plants. This trait promotes cross-fertilization which increases genetic variability, but can decrease seed-setting efficiency. Solitary individuals are unable to be pollinated, therefore it is necessary that male and female plants grow in close proximity or female plants will not produce berries.
Selected cuttings from the Washington Park Arboretum (December 15-28, 2015)
1) Ilex cassine var. mexicana
- This large, fast-growing evergreen is native to the southeastern coast of the U.S. as well as Mexico, Puerto Rico and Cuba.
- A healthy specimen can be found in grid 13-3W, just west of Lake Washington Boulevard.
2) Ilex verticillata ‘Red Sprite’
- This female, deciduous Ilex cultivar reveals large red berries when its leaves fall.
- Our best patch can be found along the path in the Joe Witt Winter Garden planted next to the male pollinizer, Ilex verticillata ‘Jim Dandy’.
3) Ilex opaca ‘Boyce Thompson Xanthocarpa’
- Evergreen tree that grows rapidly and assumes an attractive conical shape. As with most of the American Holly clade, this tree is cold hardy but not very wind-tolerant.
- Berries can be crimson-red, yellow or orange.
4) Ilex opaca ‘Emily’
- Found in the Pacific Connections Meadow plantings, this evergreen female boasts copious quantities of vivid red fruits, starting at a very young age.
5) Ilex serrata
- Located in the deciduous Holly clade on the west side of Lake Washington Boulevard, this holly spreads and suckers to form colonies.
- Small red berries are revealed in late autumn after the leaves have fallen.
December 11th, 2015 by UWBG Horticulturist
Conifer trees occasionally mutate into unusual forms, often slow-growing natural dwarfs. Thousands of these have been in cultivation for centuries. The Arboretum has only a few in its collection, sadly neglected in grid 37-1W – a corner of the Oaks area. Here are five examples:
Selected cuttings from the Washington Park Arboretum (December 1 – 14, 2015)
1) Chamaecyparis lawsoniana ‘Lycopodioides’
- Translated: “a form of Lawson’s false cypress that looks like Lycopodium” – a genus of club moss that’s said to resemble a wolf’s foot.
2) Chamaecyparis pisifera ‘Plumosa Nana’ Dwarf Sawara Cypress cv.
- Dwarf (nana), feathery (plumose), pea-bearing (pisifera) false cypress
3) Cryptomeria japonica ‘Bandai-Sugi’ Japanese Cedar cv.
- The cultivar name has been shortened recently to ‘Bandai’ because Sugi is the Japanese word for Cryptomeria, therefore is redundant.
- All parts of the flower are hidden in this genus, hence Crypto (hidden) meria (parts).
4) Picea abies ‘Gregoryana parsonii’ Norway Spruce cv.
- See Arthur Lee Jacobson’s Trees of Seattle for an explanation of the botanic name.
- Jacobson notes that only Lawson’s Cypress has more cultivars than Norway Spruce.
5) Tsuga canadensis ‘Hussii’ Eastern Hemlock cv.
- Because of people’s tendency to call all conifers “pine” or “fir”, botanists adopted the Japanese name for hemlocks – Tsuga. Does that sound too similar to ‘Sugi’?
November 23rd, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum, November 16 – 29, 2015
1) Arctostaphylus uva-ursi ‘Vancouver Jade’ Kinnikinnick or Bearberry
- Broadleaf evergreen and creeping groundcover with circumpolar distribution in northern hemisphere often found growing in association with Pitch Pine
- If there were still bears on Cape Cod, it would be a favorite food source for them.
- This cultivar, ‘Vancouver Jade’ is growing in containers outside the Graham Visitor Center.
2) Juniperus virginiana ‘Blue Coast’ Eastern Red Cedar
- A low growing, blue form of the Eastern Red Cedar
- Pioneer species found in mixed stands with Pitch Pine, reclaiming abandoned farms and grasslands
- Found growing under Pines in grid 36-4E, along nursery road
3) Morella pensylvanica Bayberry
Photo demonstrating the straightness of Arrowwood stems and their usage in making arrows
- Berries boiled to extract sweet-smelling wax used to make clean-burning candles
- Found growing in dry open sites along with Bearberry, Eastern Red Cedar and Pitch Pine
- Mass growing in Oaks Collection in grid 43-B
4) Pinus rigida Pitch Pine
- Rigid cone scales and stiff needles, hence its Latin specific epithet
- Used during days of wooden ships due to its resistance to decay
- Several young specimens in our Pinetum, grid 37-4W
5) Viburnum dentatum var. pubescens Arrowwood
- Large deciduous shrub with fruit a food source for songbirds
- Common name refers to Native American use of straight young stems as arrow shafts
- Old specimens located in southeastern Viburnum bed, grid 24-4W
October 20th, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (October 19, 2015 – November 1, 2015)
1) Cupressus (Hesperocyparis) bakeri Modoc Cedar
- A moderately-sized coniferous tree with greyish-green scale-like foliage that is dotted with white resin. It is native to the Siskiyou and Sierra Nevada Mountain ranges. A slow growing tree, usually under 90 feet over many decades.
- Considered vulnerable to extinction in the wild in the medium term.
- Located in the Pacific Connections Garden Cascadia Focal Forest above the Chilean Gateway.
2) Euonymus myrianthus Evergreen Spindle Tree
- A member of the same family as burning bush, this large shrub was discovered in western China and introduced into cultivation by famed plantsman, E.H. Wilson.
- This plant has insignificant flowers in spring and bares conspicuous yellow fruit in fall, which persist well into winter.
- Located with the Asiatic Maples collection, north of where the upper and lower trails meet.
3) Notholithocarpus densiflorus var. densiflorus Tan Oak
- Native to the mountains from southwestern Oregon through central California.
- A natural source of tannin, Tan Oak bark was used in the process of tanning leather.
- This species is particularly susceptible to “sudden oak death” Phytophthora ramorum.
- Located in Pacific Connections Garden Cascadia Focal Forest above the Chilean Gateway.
4) Picea breweriana Brewer’s Weeping Spruce
- Native to the Siskiyou Mountains, this large coniferous tree is slow growing and adapted to extreme cold. The tough flexible branches are held horizontally, forming curtains of foliage. The stiff flattened needles are dark green with two white bands of stomata on the undersides.
- Located in the Pacific Connections Garden Cascadia Entry Garden near Arboretum Drive.
5) Magnolia grandiflora ‘Monlia’ Southern Magnolia
- A medium-sized evergreen tree to 50 feet, it has large green leaves with brown indumentum covering the undersides. Large fragrant white flowers in summer are followed by large upright fruit. The species is native to the southeastern United States.
- Located at the south end of the Graham Visitors Center parking lot.
October 7th, 2015 by UWBG Horticulturist
Selected cuttings from the Washington Park Arboretum (October 5 – 18, 2015)
1) Cedrus atlantica ‘Glauca’ Blue Atlas Cedar
- A large coniferous tree with vivid, glaucous blue foliage, making it easy to identify.
- Native to Algeria and Morocco on the Atlas Mountains, these specimens can grow up to 100 feet tall and beyond.
- Located in the Pinetum near the Lynn Street play area.
2) Cunninghamia lanceolata China Fir
- Members of the family Taxodiaceae, these trees are named after James Cunningham, who originally found C. lanceolata on the Island of Chusan in 1701.
- Cunninghamias are closely related to the redwoods (Sequoia), although the foliage is similar to that of the monkey puzzle tree (Araucaria araucana).
- Located in the Pinetum near the Newton Street entrance.
3) Picea engelmannii ssp. Mexicana Engelmann Spruce
- Conical tree with bluish-green to steel-blue needles.
- Native to the mountains of western North America from Alberta and British Columbia (where it attains its greatest size) and south to New Mexico and Arizona.
4) Picea pungens ‘Glauca’ Blue Colorado Spruce
- P. pungens is allied to P. engelmannii, differing in its glabrous shoots, and in its bluer, more pungently pointed leaves.
- Native to the Rocky Mountains and southern China.
- Located in the Pinetum.
5) Sequoia Sempervirens ‘Henderson Blue’ Coast Redwood
- Native to a narrow belt of the California coastline, where summer fogs off the Pacific Ocean are frequent and mitigate the seasonal heat and drought.
- Located in the Pinetum near 26th Ave. East and East McGraw Street.
September 5th, 2015 by UWBG Horticulturist
How some trees react to high winds.
A broken Acer macrophyllum (Big Leaf Maple) stem located at the east end of Loderi Valley in the Washington Park Arboretum
1) Pseudotsuga menziesii Douglas Fir
- The detritus lying on the ground following a wind event in the Pacific Northwest provides ample evidence of how P. menziesii defends itself against wind.
- The wood of P. menziesii is brittle and can snap. When a strong wind acts on a Douglas Fir, the tree sacrifices small pieces of foliage to shed the wind’s energy.
2) Thuja plicata Western Red Cedar
- In contrast to Douglas Fir, Western Red Cedar limbs are fibrous and tenaciously strong. Long, bendable limbs whip and swing in the wind, but rarely break.
- The wind’s energy is transferred to the trunk and the cedar relies on its massive girth and extensive root system to keep it upright.
3) Populus trichocarpa Black Cottonwood
- In growth, P. trichocarpa sacrifices strength for speed.
- Just to the northwest of our Overlook Pond, a massive black cottonwood demonstrates how weak wood tends to shatter under stress.
4) Salix spp. Willow
- Often growing in wet bottomlands, the roots of willows can be shallow mats that are relatively easy to peel up when a strong wind levers a tall tree.
5) Acer macrophyllum Big Leaf Maple
- The wood of Acer macrophyllum is strong but heavy. The massive, reaching limbs can shatter mid-limb when wind pulls on the sail-like leaves.
- A recent example is located at the east end of Loderi Valley just above Arboretum Drive, although many of our big-leaf maples are festooned with “storm stubs.”
August 23rd, 2015 by UWBG Horticulturist
Selected cuttings from the New Zealand Forest in the Pacific Connections Garden at the Washington Park Arboretum (August 17 – 30, 2015)
Native to New Zealand (and Australia, Asia, and Africa). Flowers are sweetly scented and seeds are coated with a sticky substance giving the plant its name, pitch-seed.
All plants below can be seen growing in the New Zealand Forest in the Pacific Connections Garden.
1) Pittosporum eugenioides Lemonwood
- New Zealand’s tallest Pittosporum, P. eugenioides can reach 40 feet.
- Its yellow-green leaves with curly edges have a strong scent of lemon when crushed.
2) Pittosporum divaricatum
- Divaricating (stretched or spread apart) branching patterns and small juvenile foliage protect this plant from beaked predators.
- As the plant gains height, adult foliage emerges safe from predation.
3) Pittosporum patulum Pitpat
- Endemic to the South Island of New Zealand.
- Pitpat has been on the IUCN Red List as endangered since 1999.
- IUCN stands for: International Union for Conservation of Nature.
4) Pittosporum ralphii Ralph’s Kohuhu
- Thick leathery, undulating leaves sport dense white tomentum on the underside.
- Hermaphroditic flowers give way to orange-yellow seed capsules and black seeds.
5) Pittosporum tenuifolium ‘Tom Thumb’
- This purple-leaved cultivar of P. tenuifolium is a dense, slow-growing evergreen shrub with a rounded habit.
- You can find this plant in the newly-renovated courtyard of the Graham Visitor Center.