Redstem Filaree

What is redstem filaree?

Redstem filaree is a low winter annual in the geranium family, introduced from Europe and the Mediterranean and now present in nearly every US state. redstem filaree identification is easiest in spring, when small pink, five-petaled flowers and long, pointed fruits shaped like a stork's head and bill rise above a flat rosette of finely cut, fern-like leaves.

In yards it is a weed of lawns and planting beds that sprouts unnoticed in fall and has often dropped its seed by late spring. The seeds are its secret weapon: each fruit splits into segments with spiral tails that tighten in dry air and loosen in humid air, screwing the seed into the ground, and those same sharp tails can injure pets. In the West it also blankets grassland; Cal-IPC estimates it has invaded more than half of California's valley and foothill grassland, where it can crowd out native plants, mainly after disturbance such as fire.

Redstem Filaree identification: what to look for

Look at the leaves first and the fruit second. Many rosette weeds have lobed leaves, but filaree's are divided into separate, finely cut leaflets along a central stalk, like a small fern, and its beak-shaped fruits are unmistakable once they form.

• Seedlings: Hairy, with long-stalked seed leaves that have three or four broad, uneven lobes. The first true leaves are already deeply lobed or divided.
• Leaves: Hairy, alternate and finely divided into feathery leaflets, forming a rosette that lies close to the ground.
• Stems: Hairy and often reddish, spreading or upright, 1 to 2 feet long.
• Flowers: Five separate petals, pink to reddish-lavender, in small clusters at the ends of stalks.
• Fruit: A long, pointed beak held at a sharp angle to its stalk, which splits into five segments at maturity.
• Seeds: A hairy, lance-shaped seed with a slender tail that coils and bends at a right angle partway up.

Where it grows in the United States

Cal-IPC, citing USDA PLANTS, notes that redstem filaree is present in nearly every US state. In California it grows in most counties up to about 6,600 feet, is very common in valley and foothill grassland, and has invaded a large share of the state's coastal prairie and woodland. Washington State University's home-garden guide lists ornamental plantings, lawns, pastures and waste places with dry soil as typical sites.

It favors open, sunny ground with dry soil and moves in after disturbance: roadsides, pastures, heavily grazed grassland, burned areas, new landscapes and thin lawns. Dense stands can form after fire, though other plants often take the site back within a year or two. Because the seeds hitchhike on animals, shoes, tires and equipment, new yards and fields pick it up easily.

Redstem Filaree look-alikes

A few plants get mixed up with it:

• Broadleaf filaree (Erodium botrys): Its rosette leaves are lobed but not divided into separate leaflets, and its first true leaves are only round-toothed or shallowly lobed.
• Whitestem filaree (Erodium moschatum): Its stems are pale rather than reddish, its leaflets are less deeply cut, and its seedlings have seed leaves with five deep, uneven lobes.

How to get rid of redstem filaree

Pulling, digging and mowing: Hand-pull or hoe seedlings soon after the first fall rains, when stems are tender, roots are shallow and the soil is moist. A shallow hoe stroke under an inch deep is enough, and hoeing works best once the surface has dried a little. Mowing does not help, because the rosettes sit below the blade. Once plants are flowering you can still pull them, but take the whole taproot. Use a narrow tool and disturb as little soil as possible, since digging brings buried seed to the surface. Put pulled plants in municipal green waste, not a home compost pile.

Cultural control matters most, because the right conditions keep it from coming back.

• Mulch weeded areas and bare soil 2 to 3 inches deep with bark, compost, straw or similar organic mulch.
• Fill bare ground with plantings, reseeding or cover crops so there is no open soil for seedlings.
• Walk the yard regularly in fall and winter to catch new seedlings early.
• Sheet mulch large, stubborn patches.

Herbicides: Herbicides are a fallback for large infestations that hand work cannot handle. In lawns, Washington State University lists 2,4-D, MCPP (mecoprop), dicamba and triclopyr, alone or in combination products; in landscape beds, glufosinate or triclopyr products; and on bare ground, glyphosate, triclopyr or glufosinate. Use glyphosate only as a spot treatment. Plants are smallest and easiest to reach in the same fall-to-winter window that makes hand weeding work. Use only products labeled for your site and turf type, and follow the label exactly. The label is the law. If you hire someone to spray, make sure they hold your state’s pesticide applicator license; the rules for each state are in our pesticide applicator license guide.

Keeping it from coming back

Do not let it seed. Buried filaree seed can last one to three years, so removing every plant before it ripens for a few seasons running drains the seed bank, as long as you avoid digging up fresh seed in the meantime.

Limit hitchhiking seed. Brush off shoes, clothing and pets after walking through infested fields or roadsides, clean equipment, and cover bare soil quickly with mulch or plants.

Questions we get about redstem filaree

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