Afghan Thistle
Solanum hystrix R. Br. and Solanum hoplopetalum Bitter & Summerh.

Family: - Solanaceae.

Names:

Solanum comes from the Latin solamen meaning to quieten or comfort and refers to the narcotic properties of some species.

Hystrix is from the Greek hustrix for hedgehog and refers to the very spiny nature of this plant.

Hoplopetalum is from the Greek hoplon meaning weapon and petalon meaning petal and refers to the prickles on the back of the petals.

Afghan thistle refers to the belief that the Afghan camel teams spread this weed.

Some consider that Solanum hoplopetalum should be considered a hairy variety of Solanum hystrix.

Other names:

Porcupine Solanum

Prickly Potato Weed.

Summary:

Afghan Thistle is a very prickly, sprawling, colony forming herb with perennial underground stems. It has a somewhat annual top to 30 cm high, with many spines to 15 mm long on the stems, leaves and the calyx. The leaves are 3-15 cm long, shiny, yellow-green and deeply lobed, with simple and gland-tipped hairs as well as the yellow spines. The flowers are pale blue or white and 1.5-3 cm across with yellow anthers from January to March and September to November. The berry is globular, 1.5-2 cm across, at first green but turning black at maturity and mostly hidden by the enlarged prickly calyx.

It is a native species occurring in the wheatbelt and goldfields but has become a weed of crops, pastures, waste land and alongside roads and railway lines. It flowers in spring and summer.

A similar very prickly species, Solanum hystrix, which is native to South Australia, has become naturalised at Perenjori and Norseman. Solanum hystrix differs in having few or no hairs.

Description:

Cotyledons:

Two.

Leaves:

Alternate.

Petiole - Prickly.

Blade - Oval to oblong, green, 30-120 mm long by 10-50 mm wide, 3-11 deep, irregular, rounded lobes and these lobes have shallow lobes or teeth. Very spiny on both surfaces. S. hoplopetalum has shorter leaves at 30-50 mm long and less than 8 lobes with scattered fine hairs between the prickles.

Stems:

Low lying, branching, rigid, 100-350 mm long. Many yellow, straight 10-14 mm long spines. Tend to be annual. Almost hairless on Solanum hystrix. Solanum hoplopetalum is bristly hairy with simple, several-celled hairs.

Flower head:

1-5 flowered cyme on a prickly stalk(peduncle) with the flowers also on prickly stalks(pedicels).

Flowers:

Ovary -

Calyx - Prickly, 8 mm long, green, 5 lobes, bent back, persistent, very prickly near the base and prickles on veins on the back. When fruit, lobes broad, tube becomes enlarged, globular, 20-25 mm diameter, and initially encloses the developing berry.

Petals - 5, white or pale blue, fused, 15 mm long by 15-30 mm wide, bell shaped. Prickles on veins on the back.

Stamens - Very short filaments.

Anthers - Yellow, longer than the filaments, parallel sided, converging at the tips, protruding from the flower, opening at the top by 2 pores.

Fruit:

Black, soft, juicy berry, slightly flattened globular, 15-30 mm diameter. Yellowish green turning brown to purple when ripe. Initially enclosed in a prickly membranous coat(calyx) and later protruding from it. In S. hoplopetalum the fruit does not protrude from the calyx.

Seeds:

Dark grey, flattened, egg-shaped to kidney-shaped, 25mm long.

Roots:

Strong taproot to 1000 mm deep. Network of brittle horizontal laterals up to 10 mm thick about 100-200 mm below ground.

Key Characters:

Prickles present on branches, leaves and calyx.

Leaves pinnatifid, numerous straw coloured prickles, glabrous or with scattered hairs between prickles, 30-90 mm long.

From J.M. Black.

Biology:

Life cycle:

Perennial. Stems tend to die off each winter and are replaced from the rootstock in spring. It produces seed but most of spread seems to be by vegetative means.

Physiology:

Reproduction:

By seed and rhizomes.

Flowering times:

January to March and September to November in WA for Solanum hoplopetalum.

Seed Biology and Germination:

Vegetative Propagules:

Creeping lateral roots producing annual stems and herbage.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Produces seed but most spread appears to be due to rhizome extension or movement of rhizome fragments by cultivation.

Origin and History:

Australia.

Solanum hoplopetalum probably native to WA.

Solanum hystrix probably native to SA.

Distribution:

SA, WA. May be VIC also.


Solanum hoplopetalum distribution. Solanum hystrix distribution.
Courtesy Australia's Virtual Herbarium

Habitats:

Favours lighter soils and fallowed land in the 200-700mm rainfall zone. Occasionally found on clay soils.

Climate:

Temperate. Mediterranean.

Areas with a winter dominant annual rainfall of 300-700 mm and semi arid pastoral area with an annual rainfall of 200-300 mm.

Soil:

Mainly on sandy soils and occasionally on clays.

Plant Associations:

Significance:

One of the few native plants that has become a serious weed.

Beneficial:

Aboriginal food, the fleshy centre is scraped out and eaten.

Sheep and cattle eat the fruits.

Detrimental:

Weed of crops, pastures, roadsides , railways, fallows, open woodlands and disturbed areas.

Toxicity:

Not recorded as toxic.

Legislation:

Noxious weed in WA.

Management and Control:

Cultivations starting in October to November when the plant is starting to grow and repeated as necessary to prevent flowering and exhaust the rootstock provides eventual control. Patches should be treated individually to prevent contamination of clean areas. It is relatively tolerant to hormone herbicides. Picloram and glyphosate have some action at higher rates.

Thresholds:

Eradication strategies:

Kill root system by a combination of cultivation and chemical control.

Repeated cultivations (preferably with a disc plough) starting in October or November when the plant is starting to grow and repeated as necessary to prevent flowering and exhaust the rootstock, provides eventual control. Patches should be treated individually to prevent contamination of clean areas.

Manual removal is difficult because it is very spiny and the root system needs to be removed and burnt.

Grazing and mowing are not effective.

Spot spray small areas with a mixture of 100 mL Grazon® in 10 L water or 20 g Lontrel®750 in 10 L water when the weed is actively growing in summer. Lontrel provides more selective control than Grazon. Several annual applications are usually required.

A combination of spraying, followed by cultivation a few weeks later is often provides better control than either technique alone.

Plant perennial species or encourage shrub species and litter build up to reduce re-infestation.

Control in bushland is not generally warranted as it may be native to the area.

Herbicide resistance:

Biological Control:

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)

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)

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:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P749. Diagram.

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). P224. Photo.

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). #1140.20, 1140.21.

Meadly, G.R.W. (1965). Weeds of Western Australia. (Department of Agriculture - Western Australia). P130-131. Photo.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P612-613. Photos.

Acknowledgments:

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