Species Information

• shiny geranium
• Geranium lucidum
• USDA Symbol: GELU
• Oregon Noxious Weed Designation: B
• Pictures

Identification:

Shiny geranium grows predominantly as an annual weed though it may become biennial depending on moisture conditions. In Europe, it is described as growing up to 0.5 meters high and being very shade intolerant. Here in the Pacific Northwest, it is predominantly a forest understory species, very shade tolerant and only seen up to 10 -12” high (Newhouse and Brainerd 2006). Stems are red colored growing from a weak central root. Leaves are rounded, deeply lobed with a waxy appearance that makes dense infestations easy to recognize. Flowers are pink, 5 petaled and grow interspersed with the leaves; rather then above them. Geranium lucidum sprouts in the late summer or early fall with the first heavy rainstorm of the season. By early spring, patches of G. lucidum are very pronounced. During April and May, dense low-lying patches form and flowering commences. By late June and July, seed formation is completed and the plant material melts back into the forest floor. The seeds are small and rapidly transported to uninfested areas on boots, vehicles, and by wildlife. Shiny geranium grows in the Pacific Northwest predominantly as an understory species intermixed with grasses, forbs, and moss. Oak woodlands and forest openings are ideal locations for G. lucidum to establish and dominate. Conifer forests offer suitable habitat for G. lucidum though dense second growth plantations often create excessive shade, limiting growth and density.

Impacts:

Geranium lucidum has a limited distribution in Oregon and the Pacific Northwest though its effects in oak woodlands, seasonally wet ash forests and on forest edges are quite pronounced. Utilizing the abundance of early spring moisture, Geranium lucidum quickly establishes, then dominates sites pushing out many other early season wildflowers and seedlings of perennial plants. As soils dry few other plants are able to establish through the receding weed canopy. Sites dominated by heavy grass stands or false brome (another invasive plant) may be resistant to significant intrusion.

Biological Controls:

No approved biological control agent is available.

Oregon Maps of Shiny Geranium Distribution

Links:

Oregon Department of Agriculture information on shiny geranium

USDA Plants Database information on shiny geranium

GRIN Database information on shiny geranium