Lupine
Lupinus polyphyllus
Lupine (Lupinus polyphyllus), commonly known as the Large-leaved Lupine or Garden Lupine, is a striking perennial flowering plant in the legume family Fabaceae. It is one of the most widely cultivated ornamental lupines, prized for its tall, showy flower spikes that bloom in a dazzling array of colors including blue, purple, pink, white, yellow, and bicolor combinations.
• Native to western North America, it has become a beloved garden plant worldwide
• The genus name "Lupinus" derives from the Latin "lupus" (wolf), based on the ancient (incorrect) belief that lupines "wolfed" nutrients from the soil
• In reality, lupines are nitrogen-fixers that enrich the soil
• Lupinus polyphyllus is the primary parent species of the famous Russell Hybrids, developed by horticulturist George Russell in the early 20th century
• Individual flower spikes can reach 30–60 cm in length and contain hundreds of individual pea-like flowers
Taxonomie
• Natural habitats include moist meadows, stream banks, and open woodlands at elevations from sea level to approximately 2,000 meters
• The genus Lupinus comprises over 200 species, with centers of diversity in North and South America and the Mediterranean region
• Lupinus polyphyllus was introduced to European gardens in the 19th century and quickly became a horticultural favorite
• In the early 1900s, Yorkshire gardener George Russell spent decades selectively breeding L. polyphyllus and related species, producing the legendary Russell Lupine Hybrids with their extraordinary color range and dense flower spikes
• Russell reportedly spent 20+ years ruthlessly pulling out any plants that did not meet his exacting standards
• Today, lupines have naturalized in parts of Europe, New Zealand, and other temperate regions outside their native range
Root System:
• Deep, stout taproot with extensive lateral roots
• Roots bear nitrogen-fixing nodules containing symbiotic Rhizobium bacteria
• These nodules convert atmospheric nitrogen (N₂) into plant-available ammonium, enriching the surrounding soil
Stems:
• Erect, stout, and somewhat hollow
• Light green, sparsely to moderately hairy (pubescent)
• Branching primarily in the upper portion of the plant
Leaves:
• Palmately compound ("polyphyllus" means "many-leaved"), with 9–17 leaflets radiating from a central point like fingers on a hand
• Each leaflet is oblong to lanceolate, 5–15 cm long and 1–3 cm wide
• Leaflets are bright green, smooth to slightly hairy on the underside
• Arranged alternately along the stem
Flowers:
• Borne in dense, terminal racemes (spikes) 15–60 cm long
• Individual flowers are papilionaceous (butterfly-shaped), typical of the Fabaceae family
• Each flower ~1–1.5 cm long, with a standard (banner), wings, and keel
• Colors range from deep blue and violet to pink, white, yellow, red, and bicolor
• Blooming period: late spring to mid-summer (May–July in the Northern Hemisphere)
• Flowers are attractive to bees, bumblebees, and butterflies
Fruit & Seeds:
• Pods are legume-type, 3–5 cm long, densely hairy, and contain 4–8 seeds
• Seeds are oval, ~4–6 mm, mottled brown to black
• Pods mature in late summer and dehisce (split open explosively) to scatter seeds
• Seeds are hard-coated and can remain viable in the soil for many years
Preferred Habitat:
• Moist meadows, stream banks, and riparian zones
• Open woodland edges and clearings
• Roadsides and disturbed areas with adequate moisture
• Prefers full sun to light partial shade
Soil Preferences:
• Acidic to slightly acidic soils (pH 5.5–6.5)
• Well-drained but consistently moist
• Tolerates poor, sandy, or gravelly soils — its nitrogen-fixing ability allows it to colonize nutrient-poor ground
• Does not tolerate heavy, waterlogged clay soils
Ecological Role:
• As a nitrogen-fixing legume, it improves soil fertility and facilitates succession in disturbed areas
• Important nectar source for pollinators, particularly bumblebees (Bombus spp.) and honeybees
• Serves as a larval host plant for several butterfly and moth species, including the endangered Karner Blue butterfly (Lycaeides melissa samuelis) in parts of its range
• Can form dense stands that outcompete native vegetation when naturalized outside its native range
Hardiness:
• USDA Hardiness Zones 4–8
• Tolerates winter temperatures down to approximately −34°C (Zone 4)
• May struggle in regions with hot, humid summers
• All parts of the plant — especially seeds and pods — contain these bitter alkaloids
• Ingestion can cause lupine poisoning (lupinosis) in humans and livestock, with symptoms including trembling, convulsions, difficulty breathing, and in severe cases, respiratory failure
• Livestock (particularly sheep and cattle) are at risk when grazing in fields with abundant wild lupines
• Modern "sweet lupin" cultivars of other Lupinus species (e.g., L. albus, L. angustifolius) have been selectively bred to contain very low alkaloid levels and are used as high-protein food and animal feed
• Ornamental L. polyphyllus cultivars are generally not considered edible and should be kept away from children and pets
Light:
• Full sun (minimum 6 hours direct sunlight) for best flowering
• Tolerates light partial shade, but flowering will be reduced and stems may become leggy
Soil:
• Acidic to neutral (pH 5.5–7.0), well-drained soil is essential
• Sandy or gravelly loam is ideal
• Amend heavy clay with coarse sand and organic matter to improve drainage
• Avoid rich, heavily fertilized soils — lupines fix their own nitrogen and excess nitrogen promotes foliage at the expense of flowers
Watering:
• Keep soil evenly moist during the growing season
• Established plants have moderate drought tolerance but perform best with consistent moisture
• Avoid waterlogging — root rot is a primary killer of lupines
Temperature:
• Prefers cool to moderate climates
• Optimal growing temperature: 15–24°C
• Mulch around the base to keep roots cool in summer
Planting:
• Sow seeds directly in autumn or early spring; scarify hard seed coats by nicking with a file or soaking in warm water for 24 hours before sowing
• Transplant with care — lupines develop a long taproot and resent root disturbance
• Space plants 45–60 cm apart
Maintenance:
• Deadhead spent flower spikes to encourage a second, smaller flush of blooms and prevent self-seeding
• Cut back to ground level in autumn after foliage yellows
• Lupines are relatively short-lived perennials (typically 3–5 years); allow some self-seeding to maintain a population
• Stake tall flower spikes in windy locations
Propagation:
• Seed (most common), basal cuttings in spring, or division of established clumps
Common Problems:
• Aphids — particularly lupine aphids (Macrosiphum albifrons), which can colonize stems and flower spikes in large numbers
• Slugs and snails — damage young shoots
• Powdery mildew — in humid or poorly ventilated conditions
• Root rot — caused by poorly drained or waterlogged soil
• Short lifespan — lupines are naturally short-lived perennials and may need periodic replacement
Wusstest du schon?
Lupines are ecological pioneers with a remarkable superpower — they literally create fertilizer from thin air: • Through their symbiotic relationship with Rhizobium bacteria in root nodules, lupines convert inert atmospheric nitrogen (N₂) into bioavailable ammonium (NH₄⁺), enriching the soil with up to 100–200 kg of nitrogen per hectare per year • This is why lupines are widely used as green manure and cover crops in agriculture and land reclamation The "Wolf Plant" Misconception: • The genus name Lupinus comes from the Latin "lupus" (wolf), reflecting the ancient Roman belief that lupines greedily devoured soil nutrients like a wolf devours prey • The truth is the exact opposite — lupines are among the most generous soil-enriching plants on Earth Lupines and the Karner Blue Butterfly: • The endangered Karner Blue butterfly (Lycaeides melissa samuelis) depends exclusively on wild lupine (Lupinus perennis) for its larval development • Conservation of lupine habitat is critical for the survival of this butterfly species, which has declined by over 99% since the 1970s Explosive Seed Dispersal: • When lupine pods dry in late summer, the two halves of the pod twist in opposite directions as they dehisce • This sudden torsional force can fling seeds up to several meters away from the parent plant — a mechanism known as ballistic dispersal Lupines as a Superfood: • While L. polyphyllus itself is toxic, other species such as Lupinus albus (white lupin) and Lupinus angustifolius (narrow-leafed lupin) have been bred as "sweet lupins" with negligible alkaloid content • Lupin seeds contain up to 40% protein and 30% dietary fiber, making them one of the highest-protein plant foods known • Lupin-based products (flour, flakes, milk alternatives) are increasingly popular as gluten-free, high-protein, low-glycemic food ingredients George Russell's Obsession: • George Russell (1857–1951), a Yorkshire gardener, spent over 20 years breeding the Russell Lupine Hybrids from L. polyphyllus • He reportedly walked his lupine fields with a stick, destroying any plant that failed to meet his standards for color, form, or vigor • His work earned him the Royal Horticultural Society's Veitch Memorial Medal in 1937, and Russell Lupines remain among the most popular garden perennials nearly a century later
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