Weeds: Liverworts – Several species

• Family: Various
• Cycle:
• Plant type: Bryophyte (mosses & liverworts)

Biology

Liverworts are low-growing, non-flowering relatives of mosses. They are typically small plants that grow prostrate on the ground. Lacking true roots, they are attached to the soil or other growing surface by rhizoids, which are colorless, hair-like structures. The green parts of some species may be a ribbon-like or wavy thallus, while other species may be lobed or even divided into two or three rows of “leaves.” Liverwort plants may be up to 1 inch wide and can grow to 10 inches in length under good conditions. Liverworts, like mosses, reproduce by spores rather than seeds. The spores are produced in tiny capsules which protrude from the upper surface of the thallus, splitting open to scatter the spores when they are mature. Some liverworts also reproduce asexually by structures called gemmae, which may be produced inside cup-like structures on the top surface of the thallus. Gemmae are often spread by splashing water. SPECIAL INFORMATION: Some liverworts are reported to have a spicy scent due to the volatile oils they produce. This scent may deter animals from eating them. Liverworts can become significant pests in container-grown plants and nursery stock.

Habitat

Liverworts thrive in moist, humid environments, but some species are also able to survive in drier sites. They usually occur on damp soils, rotting logs, stream banks, or other moist sites, but may also become a nuisance in landscapes. In the Pacific Northwest, liverworts are most likely to be a landscape problem from early fall to late spring, when they are favored by cool, damp weather conditions.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Weather plays a large role in control of liverworts. Hot, dry conditions will slow their growth.
• Do not overwater. When possible, allow the soil surface to dry between waterings. Avoid overhead irrigation where liverworts are a problem.
• Do not apply excess fertilizer, as liverworts thrive in high-nutrient environments.
• Mulch problem areas with durable materials that drain well and dry quickly at the surface. Examples include coarsely crushed hazelnut shells, crushed oyster shells, or fabric-type weed barriers.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• Apply according to label instructions.
• NOTE: Some ingredients listed here are only available in combination.
• Read the label carefully on combination products to make sure the product is suitable for your specific situation.

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