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Lotus pedunculatus

big bird's-foot trefoil

Fabaceae

Europe, western Asia, northern Africa

Attracts Pollinators Attracts Butterflies

SunFull Sun – Part Shade

WaterHigh

HardinessZones 4–9

Overview

Lotus pedunculatus (syn. L. uliginosus) is a rhizomatous and stoloniferous perennial legume in the pea family (Fabaceae) reaching 12–36 inches (30–90 cm) tall with a 24–60 inch (60–150 cm) spread, forming dense, expanding colonies in moist to wet habitats. Stems are hollow (a key distinction from L. corniculatus), ascending to erect, branching, hairy. Leaves have the same 5-leaflet arrangement as L. corniculatus: 3 terminal leaflets plus 2 stipule-like leaflets at the petiole base, but leaflets are larger, 0.3–0.8 inch (8–20 mm) long. Calyx teeth are spreading in bud, with the two upper teeth reflexed — versus erect, converging calyx teeth in L. corniculatus. Flowers are yellow, 0.4–0.6 inch (10–15 mm) long, papilionaceous, in umbel-like clusters of 5–12 on long peduncles (more flowers per cluster than L. corniculatus). Pods radiate in the bird's-foot pattern, 0.8–1.5 inches (20–38 mm) long. Spreads aggressively by stolons and rhizomes in addition to seed. Contains cyanogenic glycosides. Nitrogen-fixing. Introduced for forage and erosion control on wet sites; persists and invades wet meadows, ditches, and riparian areas.

Native Range

Native to Europe, western Asia, and northern Africa, occurring in wet meadows, ditches, marshes, and streambanks from sea level to approximately 5,000 feet (1,500 m). Introduced to North America for forage on wet, acidic soils. Widely naturalized in the Pacific Northwest, particularly in wet pastures, roadside ditches, and riparian corridors west of the Cascades.

Suggested Uses

Used in Fabaceae identification courses alongside L. corniculatus for teaching the solid-versus-hollow stem distinction and calyx tooth orientation. Studied in wet-site forage agronomy, nitrogen fixation on acidic soils, and wetland invasion ecology. The paired Lotus spp. species (dry-site L. corniculatus versus wet-site L. pedunculatus) demonstrate habitat partitioning in introduced legumes.

How to Identify

Distinguished from Lotus corniculatus by the hollow stems (versus solid — snap a stem and look at the cross-section), the spreading calyx teeth in bud (versus erect, converging), the larger overall size and more upright habit, the larger flower clusters (5–12 versus 2–7), and the preference for wet habitats. The stoloniferous, colony-forming habit (versus taproot-centered in L. corniculatus) is apparent in established populations. Both species share the 5-leaflet arrangement and bird's-foot pod cluster.

Appearance

Size & Dimensions

Height1' - 3'

Width/Spread2' - 5'

Colors

Flower Colors

yellow

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~8 weeks

Summer Fall

Flowers from June through September. Clusters of 5–12 flowers bloom sequentially on long peduncles over 6–8 weeks. In the Pacific Northwest, peak bloom occurs in July through August. Pollinated by bees. Pods mature 3–4 weeks after pollination.

Detailed Descriptions

Foliage Description

Medium to dark green, pinnately compound with 5 leaflets (3 terminal + 2 stipule-like at petiole base), hairy

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.0 - 7.0(Neutral)

357912

Soil Types

loam clay silt peat

Drainagemoist

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

1-2 years

Care & Maintenance

Care Guide

Management is warranted where the species invades native wetlands, wet meadows, and riparian restoration sites. The stoloniferous habit makes hand-pulling difficult; all stolon and rhizome material must be removed to prevent regrowth. Mowing before seed set prevents seed bank replenishment but does not stop vegetative spread. In wet pasture settings, the species is managed as a desirable forage component. Where removal from native wetlands is the goal, repeated mowing combined with competitive native planting (sedges, rushes, native grasses) gradually reduces dominance. The wet-site preference means it occupies habitats where herbicide use is often restricted.

Pruning

No pruning applicable. Plants are mowed or cut before seed set. Stolons and rhizomes must be physically removed for eradication. In forage settings, cutting at 4–6 inch (10–15 cm) stubble height maintains productive stands.