Garden Mastery Tips
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April 2008 |
Trillium
Trillium ovatum var. hibbersonii
Nothing indicates spring is finally here more than the Trilliums blooming in the woods. The beautiful northwest native Trillium ovatum’s large, showy, white three-petaled flower is visible on any walk in the woodlands in April or May. Many people are familiar with this flower and speak lovingly of their first sight each spring, and the uplift of the heart when it is first spied through the trees. However not many people are aware that this native is one of a family of native plants, the Trilliaceae, that are unique to North America and Asia, with the vast majority in North America. In western North America, there are eight Trillium species, thirty-five in eastern North America, and six in Asia. All species are distinctly native to only their own region. A great adventure would be a Trillium Road Trip to observe and photograph them in their native habitat!
First, a general description of the Trillium family is in order. The name Trillium comes from the Latin word for three, tres. Trilliums have all their parts in threes: three leaves, three sepals, three petals. All Trillium species are divided into two subgenera: the pedicellate Trilliums and the sessile Trilliums. Our most common Northwest native, Trillium ovatum belongs to the pedicellate Trilliums, those that bear their single flower on a small stalk, or pedicel, above the juncture of the three green leaves. Another Trillium native to western Washington and Northwest Oregon is Trillium parviflorum; its sessile flower sits directly on the three leaves. Many of the sessile Trilliums also show maculation (dark spots) in their leaves.
Discovering the western Trilliums takes us to a variety of places where we can observe not only Trilliums but the wonderful surroundings in which they are found. Let’s pretend we are on a West Coast road trip for now, and look for the eight species on our route, starting from Vancouver.
The habitat Trillium ovatum favors is woodland, mixed coniferous forests. It is found from British Columbia, Canada south into California, and from the Pacific coast into western Montana. This most common of the western Trilliums blooms from late February in its most southern range into early June at higher northern elevations. The flower is conspicuous for its bright white appearance, which fades to purple red as the flower ages. A dwarf form, T. ovatum var. hibbersonii, is found only on the west coast of Vancouver Island, in British Columbia. Another variant, T. ovatum var. maculosum is found in California, and shows spotting, or maculation, in the leaves. A good starting place for our road trip is Tryon Creek State Park in southwest Portland. The Trillium Festival the first weekend in April always sees a plethora of T. ovatum in bloom, and a plant sale where a variety of native plants, including Trillium are for sale. Trillium ovatum is easily grown in gardens in a humus mixture with good drainage, and can tolerate shady conditions.
Trillium parviflorum is native only to Southwest Washington and Northwest Oregon, in the river valleys between the Coast and Cascade mountains. In April and May a good place to see them is on the Lacamas Heritage Trail, starting from near the Lacamas Meadows Golf Course. Look carefully along the path on each side of the trail in the first two miles and you will see them among the undergrowth. They are noted as a Sensitive Species in the Washington Native Plant Society list, indicating that they may become an Endangered Species if care is not taken to preserve them. The flower is less showy than some other Trilliums, even its name "parviflorum" means "small flowers", but its creamy small petals are beautiful nonetheless. In contrast to the T. ovatum, they are plants of the valley streamside meadow, not so much the mountain forest. T. parviflorum can be grown in the garden, but is not so readily available from nursery sources.
Trillium albidum
T. albidum is similar to T. parviflorum, but is a larger, more spectacular white sessile flower on a generally larger plant. T. albidum is found from Corvallis, Oregon south to the San Francisco Bay area. It grows in a variety of habitats, from the edges of mixed deciduous - coniferous forests in the Trinity Mountains of Northern California to the floodplains of river valleys. They are readily seen by taking a walk in the Eugene, Oregon area along the Willamette River or in Mount Pisgah Park. It is one of the most beautiful of the sessile Trilliums, and is available from native plant nurseries. The plants tend to form clumps of flowering stalks over time, and make a gorgeous addition to the garden, with creamy white candle-like flowers sitting directly on the leaves. Being a meadow plant, they like a little more sun than T. ovatum, but tolerate part shade.
Trillium rivale
Moving south in the Trillium family range, the next species we encounter is T. rivale. This outstanding small plant is found in Southwestern Oregon and Northern California, especially in the Siskiyou Mountains. There is some debate as to whether this small pedicellate plant is a true Trillium, and some name it Psuedotrillium rivale. However, it belongs in any discussion of the family, even if its parentage is in doubt. Its name "rivale" means "stream-loving", and aptly describes the locations where it is found in nature. The perfect small white to pink flower has pink speckles conspicuously sprinkled on the petals. It prefers to grow along steep hillsides and along road cuts, and can be found at the edges of the redwoods in Northern California. It’s clump forming habit and small size make T. rivale a perfect rock garden addition. Grow it in sandy, peaty soil where it gets at least part sun.
Trillium kurabayashi
One of the most spectacular Trilliums is T. kurabayashi. This large flowered sessile Trillium can have petals ranging from deepest red-purple to clear yellow. The leaves show dark maculation. Found mostly in the river valleys of Southern Oregon to Northern California, there is also an isolated population in the Sierra Nevada Mountains of Central California. It inhabits the lush flood plains and humus areas along the edges of the woods. Although spotting a colony of these beauties in their natural habitat along the Rogue River is very exciting, the easiest place to see them is in Portland. They are in cultivation at Leach Botanical Gardens and at the Portland Audubon Society on Cornell Road in Portland. The Portland Audubon Society has some beautiful examples with clear red flowers, in bloom in April, growing by the entrance to the Nature Store. Individual plants are sold there when available from their stock from division or seed. Leach Gardens sells seed.
Trillium chloropetalum
Farther south in the coastal hills near the San Francisco Bay area T. chloropetalum is the Trillium species found. The variety of colors seen in the sessile flower makes this one of the showier Trillium flowers. Various populations are clear red, pink, or white. In the garden, T. chloropetalum may not be as cold hardy as T. kurabayashi, but grows in similar conditions.
Trillium angustipetalum
T. angustipetalum grows in the Sierra Nevada Mountains near the Sequoia groves, and near San Luis Obispo in almost treeless chaparral. These two populations are the only ones known. T. angustipetalum can produce huge, umbrella-like leaves which reach almost two feet in diameter across the leaf whorl. Rarely found in cultivation, it is a majestic plant when found in the wild. Its narrow, dark red petals stand out against the huge green leaves. A trip to Indian Grinding Rock State Park in the Sierra Nevada Mountains can be added to our road journey to see this majestic plant in its native habitat.
Trillium petiolatum
Moving back north, the strangest western Trillium is T. petiolatum. In contrast to all other Trillium species, the leaves are petiolated, and held above the centrally located flower, which sits nestled almost on the ground between the leaves. These strange versions of Trillium grow in the prairie Palouse regions of Southeast Washington, Northeast Oregon, and Idaho and in the Blue Mountains. Blooming early in April, the plant is adapted to the dry, hot summers of its native areas, and does not do well in wet summer habitat. It is not generally available from nurseries.
We are lucky on the Pacific Coast to have eight native Trillium species, several of which have been adapted to garden culture. You can enjoy a variety in your own gardens. True of all species of Trillium, the plants take several years to flower from seed. It is best to obtain rhizomes of a desired species from a reputable source, ensuring they were not dug from the wild. See the references below for suggestions where you can legitimately obtain plants. Avoid digging them in the wild unless they are in need of rescue from development. Some of the Trilliums are now available from tissue culture, and are becoming easier to find. Our road trip included the western native Trilliums, but some of the eastern species are more readily available, and make beautiful additions to the garden, although seeing them in the wild will take a longer trip!!
Sources for Trillium species purchase
Audubon Society of Portland Native Plant Sale, May 17-18, 2008
5151 NW Cornell Rd, Portland, OR 97210
Main Phone: 503.292.6855 (Mon-Fri 9-5pm)
Bosky Dell Natives Nursery
23321 SW Bosky Dell Lane
West Linn, Oregon
503-638-5945
fax 503-638-8047
boskydellnatives@aol.com
Fraser’s Thimble Farms http://www.thimblefarms.com/
Paul Christian Rare Plants http://rareplants.co.uk/trillium/
Tryon Creek State Natural Area Trillium Festival, April 5-6, 2008
11321 SW Terwilliger Blvd.
Portland OR 97219
Phone: 503-636-4398
References
Case, Frederick W. and Roberta B. "Trilliums." Portland, OR: Timber Press, 1997.
Jacobs, Don L., and Rob L. "Trilliums in Woodland Gardens." Eco-Gardens: American Treasures, 1997.