Ecological Restoration Specialists

King County cottonwood study

King County recently published a 2-year study evaluating the effects of spraying grass versus irrigating on cottonwood live stake survival in a sunny, sandy loam site. The thought-provoking study found no benefit from applying one gallon of water per plant 5-6 times per season, but the grass-spray treatment had a positive effect. On this site, grass control effectively increased the cottonwoods’ access to water, but the irrigation did not. You can see the study results at…/King-County-Monitoring-Memo…

Holodiscus discolor – Oceanspray

Holodiscus discolor - oceanspray


Holodiscus discolor

Family: Rosaceae


Oceanspray, also known as creambush, is an understory shrub common in the Pacific Northwest and California, from sea level to 7,000 feet. It occupies a diverse set of environments, from moist, coastal forests to arid mountains. Its can sprout from the root crown when the top is destroyed, so it recovers quickly in recently burned areas and is often one of the first species to send up shoots after a fire event. As a generally fast growing species, oceanspray is quick to colonize other disturbed areas, such as recently logged land. This species is common in early succession landscapes, but occurs regularly in all seral stages.

This deciduous shrub usually grows 6-12 feet tall, and consists of multiple slender, branching stems with brown to gray bark. Its leaves, some of the first to emerge in spring, are small, alternate, and lobed. Oceanspray’s name refers to the profusion of long cascades of white flowers that cover the shrub from May to July, particularly where it grows in great abundance on marine bluffs. Terminal, plume-shaped clusters of tiny flowers emanate a sweet fragrance, attracting butterflies and providing food for honeybees. This plant is insect-pollinated and wind dispersed; the fruits are small (about 2mm long), dry, and hairy, each containing one seed. These seed clusters dry out in fall, and often persist in brown clusters into winter.

Oceanspray acts as a minor browse species for ungulates and provides nesting habitat and cover for small birds and mammals. Individual plants rarely live for over 30 years, but are highly salt and drought tolerant and can shut down or slow transpiration rates when water is scarce. This shrub can also tolerate a wide range of soil textures, and grows in soil with pH levels from roughly 5 to 7.5.

Oceanspray’s strong wood has historically been used by first peoples to fashion tools and furniture, including spears, nails and digging sticks. It is most commonly propagated from cuttings, as seeds are harder to establish.



Collect seeds when the clusters turn brown- this is during October and November. As the seeds are very small (roughly 500 seeds a gram), they can be separated from non-seed material by rubbing the clusters over a sieve. Seeds should be kept dry and refrigerated while stored.

Before planting, prepare the seeds by soaking them in fresh water for three hours. Drain water and place seeds in a freezer bag with pH neutral peat moss and stratify this mixture at 40 degrees Fahrenheit for 3-5 months, until radicles appear.

Sow seeds shallowly, being careful not to overwater. They should germinate roughly 14 days after sowing with a success rate of around 50% and should be transplanted into individual containers at this point. Seeds should establish after 28 days.

Written and illustrated by: Jasmine Doughty









Water Parsley – Oenanthe sarmentosa

Water parsley is a Pacific northwest native plant that grows on stream banks and in wet, shady areas

Oenanthe sarmentosa – Water parsely


Oenanthe sarmentosa

Family: Apiaceae

Water parsley occurs from Alaska to California and prefers wet, low-elevation habitats with full sun. It grows in saturated soil and can often be found in standing water or along streambanks. This preference, combined with the dense biomass this species creates aboveground, renders it useful in the context of wetland restoration as it slows water flow to allow the settling of sediment.

This perennial herb sports a characteristic carrot-family inflorescence, a flat-topped umbel made up of 5-20 tiny white flowers. These bloom from May to July, and produce barrel-shaped seeds. This species has soft, weak stems, which curl at the tips. If a stem touches the ground, it can send out runners from the nodes.

Although cuttings of rooted nodes can be transplanted, this plant propagates best by seed. As with many other seeds, water parsley seeds are dormant until they endure certain winter conditions. When propagating water parsley, these conditions are simulated to trigger germination through a process called stratification. Water parsley does best with a 24 hour soak, followed by 21-30 days of cold stratification. Water parsley seeds are linear and underdeveloped, meaning they exhibit endogenous, morphological dormancy. As a result, they must be allowed to finish development before germination can occur.

Although this species can seem to resemble poison hemlock (Conium maculatum), there are several ways to distinguish them. Poison hemlock is much more robust and thick-stemmed with thicker and more deeply divided leaves. The stems often sport purple blotches. Poison hemlock can grow over eight feet tall, while the maximum height of water parsley is roughly 4.5 feet. The leaves of water parsley are less dramatically toothed but more feathery and thin. Although water parsley does not cause the same symptoms as poison oak, it is still a toxic plant, like many other species in the carrot family, and should not be consumed.

Propagation Protocol

Seed description: Seeds have a strong, acrid smell, and are often slimy when removed from inflorescences. Seeds are brown when mature, and when split open, show a white endosperm.

Preparation: Keep seeds moist and store in a refrigerator. Before sowing, soak seeds for 24 hours, and cold-stratify for 21-30 days.

Sowing: Sow seeds into tubes filled with standard potting mix, and lightly cover them once sown.

Germination: Germination should occur 30 days after sowing, at a success rate of around 50%. Seedlings should be established in tubes after two months.


“Oenanthe Sarmentosa, Pacific Water Parsley.” Washington Native Plant Society: Starflower Image Herbarium. Web. 06 Oct. 2016.

“Propogation Protocol, Oenanthe (Sarmentosa).” Native Plant Network Propogation Protocol Database. Web. 6 Oct. 2016.

“Oenanthe Sarmentosa | Pacific Water Parsley | Wildflowers of the Pacific Northwest.” Web. 06 Oct. 2016.

“Oenanthe Sarmentosa Water Dropwort,Water Parsely PFAF Plant Database.” Web. 06 Oct. 2016.

We are thrilled to once again feature the fabulous artwork of SNP employee Jasmine Doughty, who left the Children’s Hands-On Museum to come back to the nursery.