Silver-leaved Nightshade

Solanum elaeagnifolium Cav.

Family: Solanaceae.

Names:

Solanum is from the Latin solamen meaning to quieten or comfort and refers to the narcotic properties of some species.
Elaeagnifolium is Latin for Oleander like leaves.
Silver-leaved Nightshade refers to the silver appearance of the leaves due to the fine white hairs and nightshade is derived from the Anglo-Saxon name for this group nihtscada which translates to night and shade and probably refers to the toxic properties of some species and may have been a reference to death and ghosts.

Other names:

Bitter Apple (South Africa)
Bull Nettle
Silver Leaf (South Africa)
Silver Leaf Bitter Apple (South Africa)
Silver-leaf Nettle (California)
Trompillo
Tomato Weed
White Horsenettle

Summary:

Erect, 400-600 mm tall, with much branched silvery-white, prickly stems, silvery hairy leaves and showy, purple, white or pink, 5 petalled flowers with green to yellow anthers in the centre from November to March and a pendulous, round, yellow, 10 mm diameter, berry fruit. It often has annual tops and an extensive perennial rhizomatous root system.

Description:

See the Weedy Solanum Key.

Cotyledons:

Two. Dull green, spear shaped with tapering, pointed tips. Sides convex to straight angular or parallel. Base tapered. Surface hairless. Petiole shorter than the blade.

First Leaves:

Dull green , oval. Tip rounded. Sides convex. Base tapered. Surface hairy. Petiole shorter than the blade.

Leaves:

Alternate.
Petiole - Short. Hairy and sometimes with spines
Blade - 25-150 mm long x 10-30 mm wide, thick, elongated oval to oblong in shape, with undulating, scalloped or shallowly lobed margins. Tapered to a blunt tip and abruptly constricted to the petiole. Often spines, 2-5 mm long, on the underside of the leaf especially on the veins. Felt like, dense, white, star type hairs especially on the under surface giving a silvery green or rarely rusty appearance. Usually a darker colour on the upper surface than the underside.
Stem leaves - Upper leaves smaller and smooth edged.

Stems:

220-1000 mm tall, erect, many branched, arising from creeping rhizomes, often silvery white due to dense, white, star type hairs. Usually has a few to many, short, slender, yellow to red spines, 2-4 mm long.

Flower head:

Cyme or 1-4 flowered raceme on a 5-10 mm stalk (peduncle) near the ends of the branches. Flowers on short, stout, 10 mm long stalks (pedicels). Pedicels lengthen and bend downwards when in fruit. Initially appear to be terminal becoming lateral with time.

Flowers:

Showy, blue, purple, white or pink, star shaped, 20-35 mm in diameter when open.
Ovary - Covered in white hairs.
Calyx - 7-10 mm long, tubular with 5, acute tipped, to awl shaped, 4-5 mm long lobes. Enlarges and bends back when in fruit. Tube 5 ribbed.
Petals - Five fused, blue, purple, white or pink petals. Short tube with 5 folded lobes arranged like spokes on a wheel and bent back.
Stamens - Very short, slender filaments.
Anthers - Longer than the filaments, oblong and tapering towards the tip, 6-10 mm long, converging at the tips, protruding from the flower, initially green and turning yellow, opening at the top by 2 pores.

Fruit:

Yellow or orange mottled to brown, soft, juicy, drooping berry, slightly flattened globular, 8-15 mm in diameter, smooth and hairless, becoming wrinkled with age. It has dark stripes when immature. About 75 seeds in a mucilaginous matrix in each berry.

Seeds:

Flattened, rounded, light and dark brown, 2.5-4 mm long, smooth, pitted surface.

Roots:

Deep, aggressive, many branched roots and creeping rhizomes that sucker freely and produce new shoots annually. Root system up to 3000 mm deep and 2000 mm wide. Horizontal roots usually occur in the top 250 mm of soil.

Key Characters:

Leaves 25-100 mm long, longer than broad, lanceolate-oblong to linear-lanceolate with entire, undulate or shallowly lobed margins, thin in texture with dense stellate tomentum, green on both faces or at least on the upper surface when fresh, becoming whitish when dry, few prickles or absent.
Herbage silvery canescent throughout, stellate hairs.
Branches with stellate hairs and usually with prickles.
Flowers few to several in simple cymes.
Calyx with no prickles, lobes acute or subulate, tube 5 ribbed, scarcely enlarged in fruit, not surrounding the berry.
Berry yellow, orange or brown, usually less than 14 mm diameter.
Herbs or shrubs
Adapted from J.M. Black and J.R. Wheeler.

Biology:

Life cycle:

Perennial. Germination takes place in autumn and it grows slowly over winter producing a deep root system. Flowering starts in November and continues well into summer. Fruit is produced over several months. Top growth usually dies down over winter leaving standing dead stubble for many months. New growth emerges in spring and the main growth occurs over summer.

Physiology:

Reproduction:

By seed and suckers.

Flowering times:

Late spring to summer in western NSW.
November to March in WA.

Seed Biology and Germination:

Most seeds are viable and long lived in the soil.
Seedlings are rarely seen in the field.
Passage through the gut of sheep increases germination.

Vegetative Propagules:

Rhizomes and lateral roots.
Root fragments.

Hybrids:

Allelopathy:

Produces toxins that reduce the growth of cotton.

Population Dynamics and Dispersal:

Spread by seed carried by water, animals, mud and vehicles. Dead top growth carrying mature fruit can be wind blown. Seed is also spread by seeds in hay. The SA infestation originated from hay and the WA infestations from contaminated Sudan grass seed.
Birds and stock spread it by eating and passing viable seed.
Root fragments can be carried on machinery but field evidence indicates that cultivation is not a major form of spread.
Root fragments down to 10 mm long can produce new plants.
New shoots can emerge from roots up to 500 mm deep.
Up to 60 berries per plant or 4500 seeds.

Origin and History:

Southern USA. Mexico. South America.
First recorded in Melbourne in 1909.
Probably introduced to SA in 1914 in hay from North America.
Introduced to WA in Sudan Grass seed.
Recognised as a serious weed in the 1950's.
Rapidly spread in NSW since 1960.

Distribution:

NSW, NT, QLD, SA, VIC, WA.
In Australia it is usually in patches of up to several hundred hectares.
Infests 350,000 ha in Australia (50-60,000 ha in SA) with potential to infest 398 million ha (Kwong et al, 1988)

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Warm temperate regions with annual rainfall of 250-600 mm.

Soil:

Wide range of soils.

Plant Associations:

Significance:

Beneficial:

Seeds used by American Indians to curdle milk and plant extracts to tan hides.
Fruit is used as a source of solasodine for steroid hormones.

Detrimental:

Weed of crops, pasture, fallows and disturbed areas.
Competes with crops and is considered capable of causing significant yield losses.
Heavy infestations can halve stocking rates1047.
Hairs from the plant contaminate cotton.

Toxicity:

The plant is reported as being toxic to stock and contains toxic levels of alkaloids.
No field cases have been reported in Australia.
Ripe berries are most toxic, then green berries then leaves. Seed may be more toxic then ripe berries.
In feeding trials, cattle were more sensitive than sheep and goats were not affected. Horses are affected overseas.

Symptoms:

Jaundice, salivation, nasal discharge, laboured breathing, bloat, trembling and diarrhoea.
Alkaloid poisoning.

Treatment:

Alkaloid poisoning.

Legislation:

Noxious weed of NSW, SA, TAS, VIC, WA.

Management and Control:

Cultivation is usually ineffective because new shoots can emerge from roots up to 500 mm below the soil surface and root fragments often reshoot. Deep ripping when dry can reduce infestations.
It competes effectively with perennial pastures, which do not reduce its growth.

Thresholds:

Eradication strategies:

Difficult to eradicate.
Treat small areas promptly with Tordon® 75-D annually. Treat at least a 2 metre buffer area around all plants.
Don't allow animals to graze plants with seeds.

Herbicide resistance:

Biological Control:

Bio control is being investigated.

Related plants:

See the Weedy Solanum Key.
Afghan Thistle (Solanum hoplopetalum)
Apple-of-Sodom (Solanum hermannii or Solanum linnaeanum)
Bittersweet (Solanum dulcamara)
Blackberry Nightshade (Solanum nigrum)
Brazilian Nightshade (Solanum seaforthianum)
Buffalo Burr (Solanum rostratum)
Desert Nightshade (Solanum oligacanthum)
Devils Apple (Solanum capsicoides)
Devils Fig (Solanum torvum)
Devils Needles (Solanum stelligerum)
Eggplant (Solanum melongena)
Flannel bush (Solanum lasiophyllum)
Giant Devils Fig (Solanum hispidum)
Glossy Nightshade (Solanum americanum)
Goosefoot Potato bush (Solanum chenopodinum)
Green-berry Nightshade (Solanum opacum)
Kangaroo Apple (Solanum aviculare)
Kangaroo Apple (Solanum laciniatum)
Kangaroo Apple (Solanum vescum)
Madeira Winter Cherry (Solanum pseudocapsicum)
Menindee Nightshade (Solanum karense)
Narrawa Burr (Solanum cinereum)
Oondooroo (Solanum simile)
Porcupine Solanum (Solanum hystrix)
Potato bush (Solanum ellipticum) is similar but has elliptical leaves and pale yellow-green berries that may have a purple tinge.
Potato climber (Solanum jasminoides)
Potato tree (Solanum erianthum)
Potato (Solanum tuberosum)
Quena (Solanum esuriale) is similar but has short stumpy anthers, elliptical leaves and pale yellow-green berries that may have a purple tinge and no prickles except may be at the base of the stem.
Rock Nightshade (Solanum petrophilum)
Thargomindah Nightshade (Solanum sturtianum)
Three flowered Nightshade (Solanum triflorum)
Tomato bush (Solanum quadriloculatum)
Western Nightshade (Solanum coactiliferum)
White-edged Nightshade (Solanum marginatum)
Wild Tobacco tree (Solanum mauritianum)
Woolly Nightshade (Solanum villosum)
Solanum arbutiloides
Solanum centrale
Solanum chippendalei
Solanum dimidiatum
Solanum dioicum
Solanum oldfieldii
Solanum orbiculatum
Solanum papaverifolium
Solanum sisymbriifolium

Plants of similar appearance:

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P10, 229. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P748. Diagram.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P593. Photo.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P660.

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). P223. Photo.

Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P32-33. Diagram.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #1140.14.

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). P535.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P609-612. Diagrams. Photo.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P146. Diagrams. Photos.

Acknowledgments:

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