Invasive of the Week: Bird’s-Foot Trefoil

Three oval, alternate clover-like leaflets appear on upright stems, with two additional leaflets below. Attractive bright yellow flowers resemble sweet pea blooms with 3-6 blooms clustered on stem ends. Bird’s-foot trefoil reproduces by seed, rhizome and aggressive above ground runners, culminating in thick mats which take over additional real estate, pushing out native species. Seed clusters look like a bird’s feet and discharge 10-20 seeds per pod when mature–imagine peas in a pod, only smaller and less charming.

Control methods: cut, pull, mow repeat! Bird’s-foot trefoil can be added to the gardener’s growing list of invasive plants for multi-year vigilance: dig using a pitchfork or garden fork to remove as much of the root as possible, repeating later in the season and in subsequent years. Dispose of flowers and seed pods–another one to not add to your compost! Cutting it out just above the root collar may help to deplete root reserves–then monitor to check for regrowth. While mowing can aid in control but not elimination, mowed remnants should be removed to avoid re-rooting. Controlled burns–useful for managing natural areas–actually enhance bird’s-foot trefoil seed germination, and pave the way for growth of new plants. General use herbicides may be employed when circumstances and magnitude warrant.

Since bird’s-foot trefoil thrives in disturbed, poor soils, enriching a site’s soil where possible may help to reduce its footprint. Introducing native plants such as goldenrods can work to out-compete this aggressive competitor.

Sources:
Misin.msu.edu
Invasive.org
mipn.controldatabase.wisc.edu

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