Herb Robert

Geranium robertianum

small five-petaled pink flower above fern like foliage

fern like foliage and pink 5-petalled flowers of low-growing Herb Robert

Plant Description

Low-growing winter or spring annual or biennial with fern-like lacy green leaves that turn red as they mature or in high light exposure. Five-petalled pink flowers, seeds grow in elongated, pointed capsules. Stems are covered in fine, glandular hairs that exude a sticky, pungent-smelling substance giving the plant its nickname “stinky Bob.” Roots are shallow.

Plant Details

Life Forms	Forb
Habitats	Disturbed sites Forest edges Forest understories Forests Little Habitats Mixed hardwood-conifer forests Oak woodlands Residential yards Riparian forests
ODA Listing	B
Soil and Moisture Conditions	Acidic soil Moist
Suggested Actions	Use BMPs to control on private property
Shade Preference	Full shade Part shade
Mature Height	up to 10"
Distribution	In Western Oregon and Washington.
Control	Pull plants by grasping base firmly to avoid breaking brittle roots. Repeat for several years until seedbank has been depleted. If using herbicides, follow all label directions.
Disposal Methods	Place plants that have set seed into a sealed bag for municipal waste disposal.
Reproduction and Spread	Reproduces by seeds, which stick to and are moved by humans and other animals. Seeds can be ejected up to 20 feet from parent plant.
Introduced	Introduced in Oregon in the 1980's. Originally from Europe, Asia, North Africa.
Look Alikes	Shiny geranium and Erodium-genus (stork's bill) geraniums.
Impact	Forms dense monocultures in forest understories, displacing native species, reducing diversity, and increasing landscape maintenance costs.
More Info	https://your.kingcounty.gov/dnrp/library/water-and-land/weeds/BMPs/Herb-Robert-Control.pdf https://weedwise.conservationdistrict.org/gero https://www.oregon.gov/oda/shared/documents/publications/weeds/herbrobertprofile.pdf