African Boxthorn

Lycium ferocissimum Miers

Synonyms - Lycium campanulatum, Lycium chinense. Lycium horridum and Lycium macrocalyx. Lycium. afrum misapplied in Australia.

Family: Solanaceae.

Names:

Lycium is from Lycia a region in Asia Minor where a similar thorny scrub, probably Berberis, occurs.
Ferocissimum is from the Latin ferox meaning fearless or bold referring to the spininess of the plant.
African Boxthorn is derived from its country of origin and the Dutch name for the plant in South Africa, boksdorn.

Summary:

African Boxthorn (Lycium ferocissimum) is a perennial, woody, hairless, semi deciduous shrub to 3-5 m high that is spiny and intricately branched. The many long spines are at right angles to the branches and each branch terminates in a spine. The slightly fleshy leaves are more or less oval, 7-25 mm long and clustered towards the tips of the rigid downward curved branches. The single, fragrant, tubular flowers are 10 mm in diameter, long-stalked and each have 4 or 5 rounded and spreading petal lobes which are pale lilac with darker purple centres. There are 5 stamens which protrude from the white throat of the flower. The fruits are bright red, succulent berries hanging from slender stalks.
Native to South Africa, African Boxthorn is a problem weed along roadsides and in waste places in the east of the south coast region and on islands of the Recherche Archipelago. Flowers can be found at most times of the year with a flush in April to May and August to December.
The berries contain toxic alkaloids.

Description:

Cotyledons:

Two.

Leaves:

Bright to dark green, arise in small clusters of 5-12 leaves at nodes along the branches and at the bases of spines. Leaves may be alternate on young shoots. Leaves may drop in late summer or in drought periods.
Stipules -
Petiole - Short or absent.
Blade - Bright green to yellowish green and similar on both sides, fleshy, oval, spoon shaped or rather elongated and tapering at the base, 10-40 mm long x 6-20 mm wide. Obtuse tip. Edges smooth and curved. Base tapering.

Stems:

Silver grey when young becoming light brown then grey and fissured with age. Densely branched, up to 5000 mm tall. The branches are rigid, much divided, light brown turning grey, at right angles and terminate in a spine. The longer branches are often drooping and shorter ones erect. There are spines 20-150 mm long on the main branches and smaller spines on the smaller branches. Branchlets terminate in a spine. Hairless.
Stems will coppice and layer or form roots where they contact the ground.

Flower head:

Single or twin flowers on slender stalks (peduncles), 6-8 mm long, in leaf axils.

Flowers:

White or purplish-white with purple blotches in centre, 10-12 mm in diameter, funnel shaped, with a delicate scent.
Bracts -
Ovary -
Calyx - Cylindrical, 6-8 mm long wit 5 unequal teeth with fine hairs. Becomes cup shaped and 2-3 lipped by splitting when in fruit.
Petals - Five waxy white lobes, nearly as long as the tube, with dark streaks inside and a purplish base. The tube is slightly longer than the calyx, with a ring of hairs on the inside around the middle
Stamens - Stick out of the flower. Downy tuft near the base of each slender filament.
Anthers - Short.

Fruit:

Globular to egg shaped, shiny, succulent, berry, 5-14 mm long, initially green turning bright to dull orange-red when ripe on a drooping stalk. 35-70 small seeds in each fruit.

Seeds:

Light brown to yellow, dull, egg shaped, smooth with small raised dots, flattened, 2.5 mm long x 1.5 mm wide.

Roots:

Deep, branched, woody tap root that suckers when damaged.

Key Characters:

Spiny branches at right angles. Red berry fruits. White-purple funnel shaped flowers. Clustered leaves.

Biology:

Life cycle:

The plant reproduces from seed and can regenerate from root segments. Seeds germinate at any time of the year with a flush in autumn and spring when temperatures are above 150C. Initially top growth is slow as the root system develops. The plant takes two or more years to reach flowering. They then flower spasmodically throughout the year with a flush in spring to summer. In winter they may drop most of their leaves and produce new ones in spring. They will also drop leaves and shut down during hot periods when average temperatures are greater than 28 degrees C. Established plants produce suckers or shoots from the roots that are often a single erect stem with many horizontal side branches which effectively protect the crown of the plant.

Physiology:

It will produce flowers and fruit from old wood, so pruning doesn't stop its potential to spread.
Tolerant of drought, salt spray and sand blasting.
Once established it is tolerant to grazing due to its spiny nature.
Grows in partial shade to full sun.

Reproduction:

By seed, suckers and root fragments.
Resprouts readily. Stem and root fragments can survive for many months then sprout.

Flowering times:

Flowers all year with flushes in April to May and August to December in WA.
Most of the year in SA.
Mainly spring to early summer in western NSW.
Mainly spring and summer in SE Australia with occasional flowers at any time of the year.

Seed Biology and Germination:

Seeds pass through bird and foxes without losing viability.
Best germination occurs at temperatures above 150C.
Seed has high viability.
Seed dormancy and longevity is probably short but may be up to 6 years.

Vegetative Propagules:

Roots form new shoots when damaged. Root fragments readily transplant.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Initially spread by intentional planting. Now mainly spread by birds, foxes and skinks that eat the fleshy berries. Water also spreads seed, stem and root fragments in waterways and machinery spreads it on roads.
Each bush may produce thousands of berries or hundreds of thousands of seeds.
Some minor spread occurs due to contamination of agricultural produce, mud and earth used in road making.
Pruning fragments will take root and grow if dumped in a suitable area. Stem and root fragments may survive for many months waiting for suitable conditions to take root.
Most seed germinates but survival over the first summer is usually low due to grazing and drought
It regenerates rapidly after fire or after top growth is cut.
Disturbance can result in mass germinations of seed.

Origin and History:

South Africa.
Introduced as a hedge plant.
Probably in Tasmania by 1845 and NSW by 1850.
In Victoria planting of Boxthorn hedges was a requirement of some early leases. However by 1904 it was a proclaimed noxious weed in some areas.
It is a target for eradication on the Abrolhos Islands and is being targeted for control by the South Coast NRM in WA.

Distribution:

ACT, NSW, NT, QLD, SA, TAS, VIC, WA.
In most parts of Tasmania. Heaviest infestations are found along the North and North-West coast and on King Island and Cape Barren Island.
New Zealand, South Africa.

Courtesy Australia's Virtual Herbarium.

Habitats:

Common near the sea in SA.

Climate:

Temperate. Mediterranean. Subhumid and semi-arid subtropical regions.
May form impenetrable thickets in high rainfall areas.

Soil:

On many well drained soils. More abundant on red brown earths, loamy and clay soils. Establishes rapidly on dry creek beds.

Plant Associations:

Dry coastal vegetation, lowland grassland, grassy woodland, woodland, plantations, heathlands, shrub lands, riparian areas and rocky outcrop species

Significance:

Beneficial:

Ornamental. Herbal medicine. When kept under control this plant forms a useful hedge and windbreak that will contain stock, including poultry.
Provides shelter for native animals.
Honey plant.

Detrimental:

Weed of roadsides, railways, pastures, waterways, coastal islands, coastal areas, sand dunes, gravel pits and disturbed areas.
Capable of invading grazing areas and excluding stock by forming impenetrable thickets.
Forms dense stands excluding most other species.
Harbours vermin.
Interferes with seal breeding on Recherche Archipelago.
Puncture tyres.
On creek lines it can prevent stock access to water.
Fruit provides a breeding ground for fruit fly, house flies, dried fruit beetles and tomato fly.
Interferes with Sea Lion breeding.
Listed as a 'Garden Thug'.

Toxicity:

Berries contain toxic alkaloids.
Fruits may be edible but can produce narcotic symptoms.

Legislation:

Declared as a WONS in 2012.
Noxious weed in most states. Secondary weed of Tasmania.
Banned in NZ.

Management and Control:

A number of herbicides can be used where mechanical removal in not practical. Repeat treatments are often required. Cultivation will control seedlings after the main bushes have been killed.
Grazing usually controls seedlings.
2,4-D is used in the USA.

Thresholds:

Eradication strategies:

Manual removal is difficult because it is so thorny and juveniles tend to break off and regrow from the roots, Seedlings can be hand pulled. Mature plants generally can be pulled successfully with a tractor and chain but require burning to prevent re establishment.
Physical removal and burning is the most common control method. Broken roots and stumps should be painted with 200 mL Access® in 10 L of diesel to control regrowth.
Individual bushes and a 5 m buffer area can be sprayed with a mix of 100 mL Grazon® plus 25 mL Pulse® in 10 L water in late spring when the plants are actively growing in late spring or when there is good foliage cover. This will control most existing plants and seedlings for about a year. Overall spraying with 100 mL glyphosate(450g/L) plus 25 mL Pulse® in 10 L water when the plants are actively growing is also effective but has no residual action.
Chemical control tends to be less effective when the plants are dormant. Best results usually occur when the plant is actively growing and in full leaf. This can be tested by shaking the tree and if all the leaves remain attached it is not entering dormancy.
Re-treat regrowth and seedlings annually. Replant tall growing, perennial native species 2 years after the last spray.
Monitor sites at least every 2 years to ensure control can be applied before new plants are old enough to set seed.
In some areas Boxthorn provides habitat for native animals and provision of alternative habitat or relocation may be required.

Herbicide resistance:

Biological Control:

Related plants:

Australian Boxthorn (Lycium australe) - native plant in WA, SA, VIC and NSW occurs in semi arid regions, is rarely more than 1.5 m tall, has smaller but broader and thicker leaves and fruits that have 5-20 seeds. In WA it occurs in the wheatbelt, goldfields and South Coast.
Chinese Boxthorn. (Lycium barbarum) - looks similar and is found in SA, VIC, NSW and QLD.
Kaffir Boxthorn (Lycium afrum) - looks similar and is found in Victoria.

Plants of similar appearance:

Nitre bush (Nitraria billardieri) is a dense round, spineless shrub, 1-2 m round, with yellow to purple, oblong fruit containing one seed. It is in coastal SA and semi arid areas.
Honey Locust (Gleditsia triacanthos) has pinnate leaves with small leaflets and large pods.
Parkinsonia (Parkinsonia aculeata) has pinnate leaves and pods.
Bursaria spinosa - a native.
Hymenanthera dentata - a native.
Scaevola spinescens - a native.

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P225-226. Photos.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P754. Diagram.

Blood, K. (2001). Environmental weeds: a field guide for SE Australia. (CH Jerram & Associates, Australia). P66-67. Photos.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P319-321. Diagram.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P587. Photo.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P639.

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

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). P220. Photo.

Hyde-Wyatt, B.H. and Morris, D.I. (1980) The Noxious and Secondary Weeds of Tasmania. (Tasmanian Department of Agriculture, Hobart, Tasmania). P53. 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). #770.4.

Moore, J.H. and Wheeler, J.R. (2008). Southern Weeds and their Control. (Second Edition). Department of Agriculture and Food Western Australia. P188-189. Photos.

Muyt, A. (2001). Bush Invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South East Australia. (R.G and F.J. Richardson, Australia). P199-200. Photos.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P601-603. Photos.

Acknowledgments:

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