Water Parsley – Oenanthe sarmentosa

WATER PARSLEY

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.

Sources:

“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.”  www.pnwflowers.com. Web. 06 Oct. 2016.

“Oenanthe Sarmentosa Water Dropwort,Water Parsely PFAF Plant Database.” www.pfaf.org 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.