Tar Vine

Boerhavia coccinea Miller, Boerhavia dominii Meikle & Hewson, Boerhavia schomburgkiana Oliver.

Synonyms - Boerhavia diffusa probably misapplied to B coccinea.

Family: - Nyctaginaceae


Boerhavia commemorates Professor Herman Boerhaave (1668-1738) who studied medicine, botany and chemistry at the University of Leyden

Tar Vine because it is often viscid or feels like tar to touch and it has a vine like growth habit.

Other Names:

Boerhavia diffusa

Common spiderling



Tah vine


Annual or perennial, summer flowering, low lying vine with opposite, unequal leaves with somewhat sticky hairs, small pink to purple flowers in summer and a stout taproot.




First leaves:


Opposite in unequal pairs.

Stipules -

Petiole - Yes

Blade - Egg shaped to lance shaped (B. repanda tends to have a heart shaped base and more pointed at the tip), 10-40 mm long, wavy edges. Upper surface green or purplish and the under surface is pale. Hairless or occasionally hairy. Sometimes sticky to touch.

Stem leaves -


Slender, up to 1 m long, low lying or bending upwards near the ends.

Flower stem - Slender, simple or branched.

Flower head:

Single bisexual flowers or in groups of 2-4 on very slender simple or branched stalks (may be stalkless in B diffusa) arising from the leaf axil.


Small, 5-10 mm long, pink to pale purple.

Ovary - superior, usually stalked, 1 celled with 1 erect ovule.

Style - Simple, dilated.

Perianth - Upper part is pink or lilac, 5 lobed, 3mm long, bell shaped and falls off with age (B. repanda is 10 mm long and funnel shaped and spreading to a diameter of ~10mm). The lower part is 3 mm long has 5 rows of glandular hairs, persists and hardens then falls with the fruit.

Stamens - 2 or 3 rarely 4, attached near the base of the perianth, Stick out of the flower slightly in B. diffusa and stick out a long way in B. repanda.

Anthers - 2 celled, attached at the back


Enclosed in the enlarged and thickened, pear shaped, 3 mm long (9mm long in B. repanda), 5 ribbed perianth with sticky hairs. The seed with its attached membrane is free.


Albuminous with an inferior radicle.


Stout, cylindrical taproot with a well developed root system.

Key Characters:

Upper perianth 3mm long - Boerhavia diffusa.

Upper perianth 10 mm long - Boerhavia repanda.

After J. Black.


Life cycle:

Summer growing perennial that responds quickly to summer rains. Dies back to the base in cold winters.


It is a C3 plant.

Drought resistant


By seed.

Flowering times:

Boerhavia coccinea - Summer in WA

Boerhavia schomburgkiana - Summer in WA.

Boerhavia diffusa - Summer to autumn in NSW, summer in SA

Boerhavia repanda - Winter and spring in SA

Seed Biology and Germination:

Seed of related species have a high protein content and digestibility similar to Soybeans.

The optimum temperature for seed germination is around 25°C. Seedlings are drought tolerant. Seeds have antibacterial action.

Vegetative Propagules:



Some legumes and Amaranthus viridis are allelopathic to the closely related Boerhavia diffusa.

Whole plant extracts of Boerhavia inhibit the germination and growth of Echinochloa.

Population Dynamics and Dispersal:

Spread by seed.

Origin and History:


Boerhavia coccinea NSW, NT, QLD, SA, WA. Tropical areas of the world. Invading the northern and eastern wheatbelt of WA. Native to the Kimberley, Pilbara and desert regions of WA.

Boerhavia diffusa NSW.

Boerhavia dominii NSW, NT, QLD, SA, VIC, WA.

Boerhavia repanda SA

Boerhavia schomburgkiana NT, QLD, SA, WA. Common in the Avon Valley of WA. Native to the Kimberley, Pilbara and desert regions of WA.



Tropical, subtropical, semi arid and temperate area


On a wide range of soils.

Plant Associations:

In a wide range of plant communities.



Palatable to stock and considered a useful summer forage. Horses on good stands are reported to become fat and tire easily when worked.

Fleshy roots eaten by aboriginals.

Some species are widely used in herbal medicine for a large range of ailments and illnesses including suppression of fungi.

May act as a growth promoting substance (Murugan et al, 1998) especially in veal claves (Wheeler, 1997).

Boerhavia extracts can increase egg laying and egg size in hens.

Rich in copper, iron, magnesium, manganese and zinc.

Extracts from Boerhavia diffusa provided 20 days control of tomato spotted wilt virus (Sadasivam, 1991).


Weed of roadsides, railways and disturbed areas.

May carry the scab disease of Cowpeas.

May act as a host for Melon viruses.

Carries Xylella fastidiosa disease of grapes.

Alternative host for Groundnut Leaf Miner.


Contains high levels of oxalates but not recorded as toxic.

The related Boerhavia diffusa was not teratogenic in rats. (That is, it did not cause birth defects)



Remove stock from infested area if toxicity is suspected.


Wildlife Conservation Act prohibits its removal from the wild where it naturally occurs.

Management and Control:

Soil solarisation to temperatures of 580C (wet) OR 690C (dry) at 5cm reduced seed banks.

Plant and encourage leguminous species. Some legumes are allelopathic to related Boerhavia species.

Pre emergent oryzalin + alachlor (0.75 + 1.75 kg a.i./ha) has given good control.

Isoproturon at 1 kg/ha probably provides control.

Pre emergent 0.5-1.5 kg fluchloralin or 0.062-0.187 kg oxyfluorfen/ha provides control.

Pre emergent atrazine 1kg/ha, methabenzthiazuron 2kg/ha and alachlor 2kg/ha provides control.

0.9 kg/ha dicamba at 20 days after emergence provides control.


Eradication strategies:

Treat with Velpar.

Herbicide resistance:

None reported

Biological Control:

Related plants:

Boerhavia coccinea

Boerhavia diffusa

Boerhavia dominii

Boerhavia repanda

Boerhavia schomburgkiana


Bougainvillea Bougainvillea spectabilis

Marvel of Peru Mirabilis jalapa

Plants of similar appearance:


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

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P333. Diagrams.

Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). p289. Photo.

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

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). P184. Photographs.

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

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #140

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


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