Robert geranium is a weedy annual or biennial with several to many more or less hairy stems spreading to ascending 10-50 cm from the base. The long petiolate leaves are pinnately lobed to dissected, with the lowest measuring from 5-15 cm long. The blades are 3-5 cm wide with the 3-5 lobed to dissected leaflets having short stalks or sessile.
The peduncles are 2-flowered. The sepals are 6-9 mm long and covered with soft hairs with bristles at their tips. The pink to red-purple petals are 8-13 mm long with rounded tips with some white and darker purplish markings. The style column measures 15-20 mm long with the beak measuring 6-7 mm.
Robert geranium may be found in moist forest soils that have been disturbed, especially along roadsides, paths, waste areas and logging landings. A prolific self-seeder (which blooms most of the year west of the Cascade Mts.), it also spreads fairly readily into the adjacent undisturbed forest.
A Eurasian species, robert geranium has been introduced to western Oregon and Washington. It can be found eastward in the Columbia River Gorge to Klickitat County in Washington and has been collected in southeastern Washington.
Unfortunately, the range of this species will spread in the decades ahead. In temperate climates, it may bloom and set seed much of the winter. Where it becomes established, it frequently covers the forest floor, crowding out the local flora.
