Yellow Lupin

Lupinus luteus L.

Family: Fabaceae.

Names:

Lupinus is from the Latin word for wolf and applied because they prey on the soil and inhabit poor soil types.
Luteus is the Latin word for yellow.
Yellow Lupin refers to its flower colour and membership of the Lupin genus.

Summary:

Yellow lupin is an erect much branched shrub with 7-11 finger-like leaflets, 4-15 mm wide and radiating from a central point. The yellow, pea type flowers are arranged in evenly spaced rings around the tall flower spike.
The densely hairy seed pods are 40-60 mm long with 4-6, black and white mottled, smooth, roundish seeds.
Native to the Mediterranean region, it is a common weed of roadsides and ungrazed areas, sometimes invading bushland and flowering in winter and spring.

Description:

Cotyledons:

Two. Fleshy, shiny, oval, tip round.

First leaves:

Similar to later leaves.

Leaves:

7-11 leaflets arising from a common central point like fingers on a hand (digitate)
Stipules - Awl shaped on the lower leaves. Narrowly egg shaped on the upper leaves.
Petiole - Long.
Blade - Of leaflet, narrowly egg shaped, bright green, 30-60 mm long x 8-15 mm wide, with a tiny flexible point at the tip. Hairy.

Stems:

Spreading or erect, 200-1000 mm tall, many branched from the base. Hairy.

Flower head:

Spike like raceme, 50-250 mm long. Flowers in evenly spaced rings around the stem.

Flowers:

Yellow pea type. Sweet odour. On 1-2 mm stalks (pedicels) with small 1-2 mm long, parallel sided bracts.
Ovary -
Calyx - 2 lipped and tubular, 7-10 mm long overall. Hairy. Tube 2 mm long. Upper lip, 3-5 mm long, with 2 deep lobes. Lower lip, 5-8 mm long, with 3 shallow lobes.
Petals - Yellow. Standard 12-16 mm long with an egg shaped limb. Wings as long as or slightly longer than the standard. Keel as long as the wings with a dark tip.
Stamens -
Anthers -

Fruit:

4-6 seeded pod, 40-60 mm long x 10-14 mm wide. Densely hairy.

Seeds:

Egg shaped to almost round, 6-8 mm wide, black and white mottled, smooth. Hairless.

Roots:

Taproot with nitrogen fixing nodules.

Key Characters:

7-11 leaflets.
Racemes pedunculate.
Flowers yellow with no blotch or stripe down the centre of the standard, whorled and on pedicels 1-2 mm long.
Seeds smooth.
Hairy annual.

Biology:

Life cycle:

Annual. Seed germinates in autumn. It grows through winter and flowers in spring. The plant dies with the onset of summer drought and high temperatures.

Physiology:

Fixes nitrogen.

Reproduction:

By seed.

Flowering times:

August to November in Perth.
Spring in WA.

Seed Biology and Germination:

Vegetative Propagules:

None.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread by seed. Most spread is due to intentional planting.

Origin and History:

Western Mediterranean. Southern Europe.

Distribution:

NSW, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate. Mediterranean.

Soil:

Most abundant on sandy soils.

Plant Associations:

Significance:

Beneficial:

Cultivated crop.
Fixes nitrogen.
Ornamental plant.

Detrimental:

Weed of crops, roadsides and disturbed areas.

Toxicity:

Three types of toxicity;
1) Lupinosis due to phomopsin produced by an associated fungus, Phomopsis leptostromiformis and results in liver damage. It occurs when stubbles or hay are grazed and may result in heavy stock losses.
2) Lupine poisoning is due to alkaloids in the plant and especially the seeds. It occurs when large quantities of the seed are consumed. Cattle sometimes suddenly die after eating green pods.
3) Some species in North America cause birth defects in cattle but this has not been recorded in Australia.

Symptoms:

Lupine poisoning symptoms are usually seen after driving and include, frothing at the mouth, falling on one side, teeth grinding, laboured breathing and convulsions. If left to rest they usually recover.
Lupinosis symptoms include lethargy, loss of appetite and condition, jaundice, photo sensitisation, loss or directional sense and death. Once symptoms are evident they rarely make a full recovery and may linger for months before death.

Treatment:

Remove stock from lupin areas. Avoid grazing stubbles or feeding large quantities of seed.
No economic treatment.

Legislation:

None.

Management and Control:

Seedlings are susceptible to cultivation and grazing. Germinations may occur after planting crops and a number of selective herbicides provide good control.

Thresholds:

1 plant/m2 is usually worth controlling in cereals to reduce contamination of grain.

Eradication strategies:

Prevent seed set for 3-4 years by mowing, grazing, cultivating, spraying or hand pulling before flowering.
Small areas can be treated with 20 mL of Tordon®75-D in 10 L of water in early winter. This will kill existing plants and leave a soil residual which controls Lupin and other broad-leaved seedlings for about a year. Larger areas can be treated with more selective herbicides such as 200 g/ha Lontrel®750 or 50 g/ha Logran®. The latter two treatments are relatively selective in bushland. For hand spraying mix 25 mL wetting agent plus 4 g Lontrel®750 or 1 g Logran® in 10 L of water. Metsulfuron(600g/kg) at 10 g/ha provides good control but is less selective. Glyphosate is relatively ineffective. Grazing by native animals usually keeps Lupins under control in healthy bushland.

Herbicide resistance:

Biological Control:

Related plants:

Narrow-leaved Lupin (Lupinus angustifolius)
Pearl Lupin (Lupinus mutabilis)
Sandplain Lupin (Lupinus cosentinii)
Tree Lupin (Lupinus arboreus)
White Lupin (Lupinus albus)
Yellow Lupin (Lupinus luteus)
Lupinus hirsutus
Lupinus pilosus
Lupinus polyphyllus cv. Russell hybrid is naturalised in NSW, Victoria and New Zealand and has long sprays of brightly coloured flowers.

Plants of similar appearance:

References:

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). 470.

Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P99-104.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P152-153. Photo.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). 768.5.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P281-282.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.