All lupins found wild in New Zealand are similar in having palmate leaves (shaped like a hand), with several leaflets all rising from the central stalk
Sends up tall, brightly coloured inflorescences bearing many pea-like flowers.
Tree lupin (Lupinus arboreus)
Most common lupin species in New Zealand
Hairy, soft-wooded, short-lived perennial shrub with spreading branches and a stout taproot. It can grow up to 3 m tall but is usually shorter
Pea-like, white or yellow flowers are strongly-scented and arranged in spikes 10-30 cm long
Leaves are green to grey-green in colour, hand-shaped, divided into five to eleven lance-shaped, stalked leaflets and sparsely covered with fine silky hairs.
Russell lupin (Lupinus polyphyllus)
Very common garden plant that has been widely planted in ‘beautification’ projects As a garden escape it has naturalised in Wellington Province, south-west Nelson, inland Westland, Canterbury, and Central Otago where it has invaded braided rivers
Herbaceous perennial species, with stalked leaves all originating from the crown
Very beautiful spikes of pink, white, orange, blue or purple pea-like flowers
Often features in scenic photographs of Mt Cook and other iconic South Island places
Has been proposed as a useful fodder plant in South Island hill country.
Blue lupin (Lupinus angustifolius)
Naturalised in scattered dry waste places in North and South Auckland, Manawatu, Wellington, Marlborough, Canterbury and Otago
Usually blue, unscented flowers. Leaves with 6-9 leaflets
Annual life-cycle
Often used by gardeners as a leafy green manure crop and has been used as a fodder crop. Plants grow to 1 m tall
Plants infected by fungus can be poisonous. However, poisoning is rare in New Zealand.
Yellow lupin (Lupinus luteus)
Naturalised only on coastal areas near Kaitaia and on Great Barrier Island
Annual species with bright yellow flowers in distinct whorls on the flower stalk and nine to eleven leaflets on each leaf.
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Biology
Origin and habitat
All lupins are members of the pea family and nodules on their roots contain rhizobial bacteria that fix atmospheric nitrogen
Because of this nitrogen-fixing ability lupins can modify the soils in which they grow, often making soils more suitable for nitrogen-demanding weedy species.
Tree lupin is native to California and was first found naturalised in New Zealand in 1899
Found on sand dunes, river beds, developed sand and pumice country and is common along roadsides throughout New Zealand
Formerly used to stabilise sand dunes and as a nitrogen-fixing crop before and during the planting of pines on sand country. However, a fungal disease (Colletotrichum gloeosporioide) dramatically reduced tree lupin populations in the 1990s
Tolerant of wind, salt, drought, heat, cold, fire, and low fertility, but is intolerant of moderate shade and waterlogged soils
The leaves are bitter-tasting and not readily eaten by livestock.
Russell lupin is originally from western North America and was first found as a naturalised species in 1958
All New Zealand plants are of cultivated hybrid origin, rather than pure Lupinus polyphyllus
Tolerant of wind, high and low temperatures
Has also been promoted as a fodder species for South Island high country, although is not usually grazed by livestock if there is alternative feed available
A popular ornamental garden plant that has ‘escaped’ and successfully adapted to challenging environments, or has been deliberately spread to ‘beautify’ the environment
Has become a major problem in conservation areas and in braided river beds, where it can divert river flows and shelter pest animals.
Blue lupinoriginates from southern Europe, Asia Minor , and North Africa, and was found to be naturalised in New Zealand in 1958
Has been grown as a crop, especially in Western Australia, but not rarely in New Zealand
Found naturalised in dry waste places and in river beds, but is not very common.
Life-cycle
All lupin specie are spread by seeds which shed explosively from the pods on hot days
Like most legumes the seeds can survive in the soil for many years.
Benefits
Lupins are widely used in many countries as attractive garden plants
Used as animal fodder crops and green manure because of their nitrogen-fixing capabilities.
In New Zealand blue lupins are commonly grown in home gardens as a winter crop that is turned in in early spring to improve the soil.
Impacts
Lupins, because of their ability to fix nitrogen, can modify the soil in which they grow, making it more suitable for the growth of weedy nitrogen-demanding plant species
They can also form dense stands of vegetation that make it hard for native species to regenerate and grow under their cover
They can block river and stream flows, especially in braided rivers, and can cause channel diversion and sometimes flooding
Native birds may not flourish so well in river beds invaded by lupins, especially since the lupins can provide shelter for vermin like rats and stoats and degrade nesting sites.
Control
Non-chemical control
Slash tall plants close to ground and leave the debris to break down
Hand pull or dig small plants and again leave on the site to rot down.
Chemical control
These weeds are readily controlled by a number of herbicides but as they frequently grow in areas where access and use of spray equipment is a problem, chemical control is seldom a good option
Cut down the plants and paint the stumps at any time of the year with glyphosate, metsulfuron-methyl, triclopyr, Yates Hydrocotyle Killer, or Vigilant gel
Weed wipe, again at any time of the year, with glyphosate, triclopyr, metsulfuron-methyl or Yates Hydrocotyle Killer. Add a penetrant in all cases
They are also readily controlled in pasture with 2,4-D ester, clopyralid, triclopyr and picloram. Note however that these herbicides are also damaging to clovers to a lesser or greater extent
ALWAYS READ PRODUCT LABELS BEFORE APPLYING: Consult your farm consultant, industry rep or the New Zealand Agrichemical Manual for more information about chemical control.
Further information
Popay I, Champion P, James T 2010. An illustrated guide to common weeds of New Zealand. New Zealand Plant Protection Society, Christchurch, New Zealand. 416 p.
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