Birdsfoot Trefoil (\(Lotus corniculatus\)) is a widespread perennial legume often seen growing in fields, along roadsides, and in lawns across temperate regions. This non-native plant, introduced primarily for forage and erosion control, is frequently encountered by foragers due to its distinctive appearance. Determining if this common plant is safe for human consumption requires examining its identifying features, traditional uses, and the natural chemical compounds it contains.
Identifying Birdsfoot Trefoil for Safe Foraging
Positive identification is the first step before consuming any wild plant. Birdsfoot Trefoil is a low-growing plant, typically sprawling or ascending to a height between 4 and 12 inches, though more erect forms can reach up to 30 inches. Its foliage is unique, possessing five leaflets on each leaf. Three terminal leaflets appear clover-like, while two smaller leaflets are positioned at the base of the leaf stalk.
The flowers are bright, pea-like yellow, often tinged with red or orange before fully opening, earning it the nickname “bacon-and-eggs.” These flowers occur in tightly packed clusters of two to eight at the end of a long stem. The most distinguishing feature, which gives the plant its name, is the seed pod structure. After the flowers fade, the plant develops slender, cylindrical pods, about one inch long, which radiate from the stem junction resembling a bird’s foot or claw.
Culinary Uses and Preparation
Birdsfoot Trefoil has a history of limited culinary use, focusing particularly on the younger, more tender parts of the plant. The young shoots and leaves have been traditionally gathered and cooked as a green vegetable. When prepared, they offer a mild, slightly grassy flavor and can be used similarly to spinach or other potherbs.
The flowers are the most frequently mentioned part in traditional preparations. Dried flowers have been used to make a caffeine-free herbal tea infusion. This involves steeping the dried petals in hot water, sometimes resulting in a mildly calming beverage. While young seed pods are occasionally nibbled, mature seed pods are typically avoided due to their tough texture.
Understanding the Toxicity Risk
The primary safety concern with Birdsfoot Trefoil stems from its natural defense mechanism: the presence of cyanogenic glycosides. These compounds, which include lotaustralin and linamarin, are common in many plants, particularly those in the legume family. When the plant tissue is damaged, an enzyme breaks down these glycosides, releasing hydrogen cyanide (HCN), a toxic compound. The concentration of these glycosides is highly variable, depending on the specific strain, maturity, and environmental factors. While the dose is generally low enough that it is metabolized quickly by the human body, cooking or thoroughly drying the plant material significantly reduces the concentration of these volatile compounds, lowering the inherent risk.
Dangerous Look-Alikes
Foraging safely requires distinguishing Birdsfoot Trefoil from other plants that share similar characteristics but may be toxic. Yellow Sweetclover (\(Melilotus officinalis\)) is a common look-alike, but it can be differentiated by its smaller flowers arranged along the stem in racemes, rather than the flat-topped clusters characteristic of Trefoil. Some toxic Vetches (\(Vicia\) species) may have similar growth habits, but they are distinguished by the presence of tendrils, which Birdsfoot Trefoil lacks. Additionally, Birdsfoot Trefoil leaves have smooth edges, unlike similar legumes such as non-native clovers and medics, which have finely toothed leaflet edges. Correct identification should rely on the unique five-leaflet structure and the distinctive “bird’s foot” seed pod formation.