Blackberry Nightshade

Solanum nigrum L.

Synonyms - Solanum opacum

Family: - Solanaceae.

Names:

Solanum comes from the Latin solamen meaning to quieten or comfort and refers to the narcotic properties of some species.
Nigrum means black and refers to the black fruit.
Blackberry Nightshade refers to its black, berry fruit and membership of the nightshade family. 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:

Black Nightshade
Nightshade
Potato Bush
Tomato Bush
Wild Currants.

Summary:

Blackberry Nightshade is an erect herb or small short-lived bushy shrub to 1 m high. The leaves are 2-7.5 cm long, entire or very shallowly lobed. The flowers are white, in short-stalked clusters of 4-12 flowers. Each flower is star-shaped and about 10 mm across with 5 spreading white petals. The succulent, globular berries are usually 6-8 mm across, at first green but becoming dull black at maturity. Each berry contains 25-35 seeds about 2 mm long.
It is probably native to Europe, and is now a common weed of horticulture, gardens, crops, pasture and waste land. It is readily spread by birds into bushland and flowers for much of the year.

Description:

A morphologically variable species.
See the Weedy Solanum Key.

Cotyledons:

Two. Oval, green on top with purple tinges underneath, 13-17 mm long overall with a petiole 4 to 5 mm long, acute tip. Base tapered. Glandular, short hairs are normally present on the upper and lower surfaces of the blade or along the edges, on the petiole and hypocotyl. The seedling has a green hypocotyl often with purple tinges. It has no epicotyl. No veins on the upper surface, mid vein a green line on the lower surface.

First Leaves:

The leaves grow singly, the first being oval, 18-25 mm long overall, acute tipped with a petiole 5-8 mm long. Base tapered to squarish. Glandular hairs are present on the upper and lower surfaces or edges and on the petiole. Short, stout non-glandular hairs occur on the upper leaf surface also. Prominent veins.

Leaves:

Alternate. Does not develop as a rosette. Later leaves are generally similar in shape to the first leaf, though as the plant grows they become more diamond shaped.
Petiole - 10-30 mm long, often purplish with a narrow wings that may extend down the branch. Flattened on the upper surface. Low lying hairs.
Blade - 20-100 mm long by 11-70 mm wide, soft, egg to diamond shaped or oval, entire, wavy or sparingly toothed, often slender towards the tip or rounded. Usually darker green on the upper surface and lighter green sometimes tinged with purple on the lower surface. Smaller towards the top of the stem. Few or many short, curved, stout hairs on the upper and lower surfaces. Prominent veins indented on the upper surface and ridged on the lower surface.

Stems:

Erect, 200-1000 mm long, stout, green or tinged with purple to quite dark, branch from the base and along their length, solid and circular or polygonal in cross-section with one or more longitudinal ridges which often carry tubercles. Few curved or glandular, low lying, hairs or no hairs are present. Often shrubby, sometimes woody at the base. No spines. Stem architecture is quite dependent on the environment.

Flower head:

Extra axillary (arise from the stem above the leaf axil), 3-12 flowers in umbel like cymes or racemes. Common stalk(peduncle), 10-25 mm long carrying flower stalks(pedicels), 5-10 mm long. Peduncle and pedicels bent downwards when in fruit.

Flowers:

Star shaped, 4 to 18 mm in diameter, with five white petals and yellow anthers. Self fertilising.
Ovary - Style slender, usually straight, sometimes branched.
Calyx - 1.5-2 mm long, 5, rounded, triangular lobes that are 0.5-1 mm long, with obtuse or acute tips. Bent back when in fruit.
Petals - 5-7 mm long by 8-10 mm wide, star shaped, white or rarely tinged with purple, short tube with 5, bent back, lance shaped, folded lobes arranged like spokes on a wheel, low lying hairs on the outside.
Stamens - 5, grouped in a cone around the pistil. Very short filaments that are sparsely hairy.
Anthers - 5, erect, prominent, yellow, longer than the filaments, parallel sided, 2-2.5 mm long, converging at the tips, protruding from the flower, opening at the top by both pores and slits that later extend to the base. Large pollen 26-35 um diameter.

Fruit:

Soft, juicy, globular, drooping berry, 5-10 mm diameter. Normally starts off green and turns dull black or purplish in colour.

Seeds:

Yellow to dark brown. Tear drop shape in outline, flattened, 25-35 per berry, 1-2.2 mm long. Surface finely network patterned, and hairless.

Roots:

Light coloured taproot and many laterals. High shoot:root ratio.

Key Characters:

Erect annual or rarely biennial.
Prickles absent.
No stellate hairs, not obviously hairy.
Glabrous or with scattered simple hairs.
Leaves egg shaped to rhomboid, petiolate, entire or sparingly toothed margin.
Inflorescence arises directly from the branches
Flowers star shaped, white or tinged with purple or white with a greenish-yellow star, up to 10 mm wide, 3-7 in umbel like cymes or short racemes.
Calyx persistent.
Mature berry dull black, rarely yellow-green, no sclerotic granules, no white flecks, with 15-60 seeds.
Seeds about 1.8-2.2 mm long, usually yellow or nearly white.
Pollen 26-35 um diameter.
From J.M. Black, J.R. Wheeler, Rogers and Ogg.

Biology:

Life cycle:

Annual or rarely perennial herb or small shrub. Germination occurs mainly in spring and summer. Flowering occurs 5-9 weeks after germination and continues until the plant dies. Plant death is usually determined by environmental conditions rather than age and drought, cold or frost kills them. In some environments they behave as annuals and in milder conditions the act as perennials.

Physiology:

Produces alkaloids, glycosides and accumulates nitrates.
Hexaploid (2n=72) possibly derived from Solanum americanum, Solanum villosum and Solanum sarrachoides.
Does not tolerate drought.

Reproduction:

By seed.

Flowering times:

Most of the year in WA.
Mainly spring to autumn and occasionally in winter in western NSW.
Most of the year in SA.

Seed Biology and Germination:

Produces dormant seed.
Mulching reduces germination.
Optimum germination is at alternating temperatures of 20/300C. The range of temperatures at which seed will germinate depends on the time of the year. Alternating temperature generally give better germination than constant temperatures.
Fluctuating temperatures are required to break dormancy.
Moist storage at cool temperatures enhances germination.
There is considerable variation in the reported dormancy. This ranges from 99% germination in the spring after exposure to winter temperatures to 27, 2 and 0% germination after 2, 8 and 9 years storage at room temperature respectively in Andersen's (1968) work. Roberts and Lockett's (1978) report 11% of the seed remaining viable in the soil after 5 years.
In agricultural situations, most seed appears to germinate within a year or two of production.
Germination is usually staggered.
Strongly seasonal germination pattern from September to March.
Fresh seed is dormant. Dormancy is cyclical and least in spring to early summer and greatest in winter.
The effect of light is variable. Lower light intensities or darkness are generally more favourable for germination. Red light appears to inhibit germination.
Best germination occurs when seed is about 2.5 mm deep in soil.
Rinsing with water has little effect on germination.
Gibberellic acid improves germination.

Vegetative Propagules:

None.

Hybrids:

Plants are primarily self fertilising.
Many forms and varieties.
Solanum opacum has green berries.
There are 11 species in the Solanum nigrum complex in Australia, 2 are native, 8 naturalised and 1 cultivated. (Henderson, 1974).

Allelopathy:

Ecology, Population Dynamics and Dispersal:

Spread by seed.
Up to 178,000 seeds can be produced by one plant.
Seed production favoured by long photoperiod and high light intensity.
Early germinating plants takes 7-9 weeks before flowering whilst late germinating plants take 5-6 weeks before flowering.
Blackberry Nightshade often appears as a problem weed only after other weeds have been controlled.
They are essentially self fertilising so distinct ecotypes tend to develop depending on the management practices and environment under which they are growing. With a change in practice the few hybrids that are tolerant of the new practice quickly form a new relatively true breeding ecotype suited to surviving under the new conditions.

Origin and History:

Europe. Cosmopolitan.

Distribution:

ACT, NSW, NT, QLD, SA, TAS, VIC, WA.
Blackberry Nightshade is common in the Southern and Northern parts of Tasmania but found less frequently in the Midlands.
Occurs between lat 540N to 450S on a world scale.

Solanum nigrum distribution.
Courtesy Australia's Virtual Herbarium.

Solanum americanum distribution.
Courtesy Australia's Virtual Herbarium.

Habitats:

Prefers shaded areas.

Climate:

Temperate. Mediterranean.

Soil:

Wide range.
Most abundant on high fertility soils.

Plant Associations:

Many.

Significance:

One of the worlds worst weeds (Holm) being a weed of 37 crops in 61 countries.

Beneficial:

Mature fruit used for jam.
Used as a herb.
Used in dyes in preserved fruits.

Detrimental:

Weed of fallows, cultivation, vegetables, pasture, gardens, stock yards, disturbed woodlands, streams, wetlands and disturbed areas.
It is common in vegetable crops. It occurs occasionally during the establishment stage of pasture. It can be competitive, and in pea crops is a particular problem since its black berries cannot be distinguished from peas by the processing equipment.
In field beans, harvesting ruptures the berries causing staining of the beans and adhesion of soil resulting in degraded quality.
It is an alternate host for diseases including anthracnose, Cercospora, blight, leaf spot and powdery mildew, at least 13 nematodes, 3 bacterial diseases, 7 fungal diseases including Rhizoctonia and over 30 crop viruses.
Stains wool.

Toxicity:

Considered variably toxic overseas and a few field cases of toxicity in have been reported in Australia.
May contain toxic alkaloids and toxic levels of nitrates.
The plant does not appear to be toxic at all times, and toxicity may be restricted to certain stages of growth, be influenced by particular growing conditions, or be a characteristic of only certain strains of what is a somewhat variable species.
In South Australia, Black(1965) considers the ripe fruit are harmless.
Fruits from NSW were not toxic when tested.
Green berries poisoned a child in WA. (Gardner, 1956).
Immature fruit should be treated as toxic.
Most cases of suspected poisoning are due to consumption of leaves or unripe fruit.
May be toxic to pigs.

Symptoms:

Glycoside poisoning; Abdominal pain, vomiting, constipation or diarrhoea, blood stained faeces, loss of appetite, death or recovery.
Alkaloid poisoning; drowsiness, breathing difficulty, salivation, trembling, staggering.

Treatment:

Remove stock from infestations. Avoid releasing hungry stock onto dense infestations.

Legislation:

None.

Management and Control:

Blackberry Nightshade is seldom a problem in well-managed pastures. It usually results from bared soil in the late spring to early summer period. In summer crops there are a number of selective herbicides for various situations.
Herbicide trials:
In Lettuce trials;
Dimethenamid-p at 720 g.a.i./ha applied post transplanting or
Pendimethalin at 990 g.a.i./ha pre planting followed by propyzamide at 2250 g.a.i./ha post transplanting or
Pendimethalin at 990 g.a.i./ha pre planting followed by imazamox at 32 g.a.i./ha early post emergence or
Pendimethalin at 990 g.a.i./ha pre planting followed by phenmedipham at 785 g.a.i./ha early post emergence all gave good control of Blackberry Nightshade (Frost and Hingston, 1994)

Thresholds:

Very low in processing peas.

Eradication strategies:

Prevent seed set for several years.
In agricultural situations, graze heavily or spray to kill spring growth and bare the soil.
Cultivate in early summer to kill seedlings and encourage germination of the seed bank.
Spray with Tordon 75-D® at 2 L/ha to kill seedlings and provide residual control.
Plant perennial species and maintain a mulch over summer.
In bushland situations, manually remove plants before flowering. On larger infestations, 1 L/ha Starane® or 20 mL in 10 L water, applied when the weed is actively growing in summer, will provide reasonably selective control. Plant perennial species that provide a good mulch over the summer period to reduce re-invasion. Control infestations within 5 km of the target area to reduce dispersal of seed by birds.
1 L/ha 2,4-D amine(500g/L) or 20 mL in 10 L water is also used for the control of young plants in early summer and at these rates causes little damage to most established native species.
Encourage shrub species and litter build up to reduce re-infestation. Blackberry Nightshade usually only germinates in bare soil.

Herbicide resistance:

Some populations have developed resistance to atrazine.

Biological Control:

Related plants:

See the Weedy Solanum Key.
Afghan Thistle (Solanum hoplopetalum)
Apple-of-Sodom (Solanum hermannii or Solanum linnaeanum)
Bittersweet (Solanum dulcamara)
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 or Solanum nodiflorum) is very similar but has shiny black berries, smaller anthers, smaller pollen and smaller, more numerous seeds (40-50 seeds per berry, each 1-1.5 mm long).
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)
Potato climber (Solanum jasminoides)
Potato tree (Solanum erianthum)
Potato (Solanum tuberosum)
Quena (Solanum esuriale)
Rock Nightshade (Solanum petrophilum)
Silver-leaved Nightshade (Solanum elaeagnifolium)
Thargomindah Nightshade (Solanum sturtianum)
Three-flowered Nightshade (Solanum triflorum) differs in its more deeply lobed leaves which have 7-9 toothed lobes, its flowers which are in clusters of only 3 and also in its larger marbled whitish green berries that are 8-12 mm across.
Tomato bush (Solanum quadriloculatum)
Western Nightshade (Solanum coactiliferum)
White-edged Nightshade (Solanum marginatum)
Wild Tobacco tree (Solanum mauritianum)
Woolly Nightshade (Solanum villosum) is very similar but woolly hairy, with a longer corolla that is 3-4 times longer than the calyx. The ripe fruit is oval and reddish in colour.
Solanum arbutiloides
Solanum centrale
Solanum chippendalei
Solanum dimidiatum
Solanum dioicum
Solanum oldfieldii
Solanum orbiculatum
Solanum papaverifolium
Solanum sisymbriifolium

Plants of similar appearance:

This plant is often incorrectly identified as the highly toxic Deadly Nightshade (Atropa belladonna) which does not occur in Australia, though there is herbarium sample in Tasmania.
Young Blackberry Nightshade has a superficial resemblance to Amaranthus. Blackberry Nightshade is generally darker in colour while its cotyledons, first leaves, and flowers are completely different from those of Amaranthus.

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P230. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P743, 746. Diagram.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P320.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P588. Photo.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P665-668. Photo.

Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P164.

Henderson, R.J.F. (1974). Solanum nigrum L. (Solanaceae) and related species in Australia. Contributions to the Queensland Herbarium 16:1-78.

Holm, L.G., Plucknett, D.L., Pancho, J.V. and Herberger, J.P. (1977). The World's Worst Weeds. (The University Press of Hawaii) P430-435. Diagrams.

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). P222-223. Photo.

Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P64-65.

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). #1140.29.

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). P535-536. Diagram.

Rogers, B.S. and Ogg, A.G. (1981). Biology of Weeds in the Solanum nigrum Complex (Solanum Section Solanum) in North America. (U.S. Department of Agriculture, Science and Education Administration, Agricultural Reviews and Manuals. P1-30.

Stucky, J.M. (1981). Identifying Seedling and Mature Weeds Common in the South eastern United States. (The North Carolina Agricultural Research Service and The North Carolina Agricultural Extension Service, North Carolina State University, Raleigh) P110-111. Diagrams. Photos.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P148. Diagram. Photos.

Acknowledgments:

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