Erect spiderling (Boerhavia erecta)

Assessment ID: 1014
Jurisdiction: North Territory
Methodology: Northern Territory Weed Risk Management System - terrestrial
Management area: Darwin Region

Notes: Weed Risk Assessment Technical Report available at: https://territorystories.nt.gov.au/10070/373016

Status: PUBLISHED
Last updated: 25/8/2025 1:39:58 pm AEST

Questions answered: 39 / 47

Weed Risk: 29.50 (Low)
   Invasiveness (raw/adjusted): 8.00 / 6.664
   Impacts (raw/adjusted): 1.00 / 0.526
   Potential distribution (raw/adjusted): 16.00 / 8.416

Feasibility of Control: 391.45 (Very high)
   Control costs (raw/adjusted): 7.00 / 6.363
   Current distribution (raw/adjusted): 10.00 / 10.000
   Persistence (raw/adjusted): 8.00 / 6.152

Result: Monitor

Invasiveness

A1. What is the ability of the plant to establish amongst intact native environments?
Answer: Medium

Comments: 
In Taiwan, so far, plants of the species were found … quickly spreading along [the] railroad. The plants of the species grow in open areas with arid or sandy soil, revealing its status as a pioneer species. This weed species can be expected to occur along [the] railroad of the lowland of the whole island in near future (Chou et al. 2004).

Erect tar vine rapidly invades cultivated plots, pastures and the understorey of native woodlands (DAFF 2001).

Boerhavia erecta occurs in open bushland, on waste ground, in agricultural land and along roadsides, up to 1500(–2500) m altitude, usually on sandy or rocky soils. It prefers sunny localities and a seasonal climate with a pronounced dry season (Schmelzer 2006).

In Darwin, seedlings have been always found in disturbed or slightly disturbed vegetation, e.g. by water or mechanical means. It prefers open, sunny areas (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

A2. What is the reproductive ability of the plant?

(a) Time to seeding
Answer: 1 year or less

Comments: 
Under favourable conditions, flowering starts 2 weeks after germination and the first seeds ripen 2 weeks later (Schmelzer 2006).

Flowering started at the sixth leaf stage when the plants were 17 days old. Petals dropped off one day after blooming and seed set followed. First matured seeds were observed 22 days after seedling emergence (Libertino 1984).

For the eradication program, we initially planned to visit every 4 weeks, but found it was too long and reduced the time between visits to maximum 3 weeks to ensure no plants had mature seed (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

(b) Annual production of viable seed /m2 or /plant
Answer: High

Comments: 
A well-developed Boerhavia erecta plant can form 20 000 – 30 000 seeds per year (Schmelzer 2006).

Number of Boerhavia erecta seeds produced was significantly increased from 3400 to 8250 seeds when grown at 175 kg N HFS application (Libertino 1984).

In screenhouse studies, highest germination of 26.0% was attained when seeds were sown on the soil surface in pot (Libertino 1984).

(c) Vegetative reproduction
Answer: None

Comments: 
Boerhavia erecta is propagated by seed (Schmelzer 2006).

A3. Do propagules of the plant have properties that allow them to be dispersed long-distance by natural means?

(a) Flying animals (birds, bats)
Answer: Yes

Comments: 
The mucous coat of the anthocarp shows a distinct sticky swelling when ripe, with which it clings to mammals and birds for wide dispersal (Schmelzer 2006).

Erect tar vine could enter Australia as a contaminant of clothing and footwear, or on migratory birds (DAFF 2001).

While B. erecta seeds are normally not sticky, when wetted while still attached to the plant, a slimy substance forms, allowing seeds to adhere to passing animals (Pijl, van der 1982, Holm et al. 1997, Van der Pijl 1982).

Fruits are smooth and generally less able to attach than those of the native Boerhavia species (J. Westaway, NAQS, pers. comm. 13/6/2018).

(b) Other wild animals
Answer: Yes

Comments: 
Its seeds can be spread long distances by accident, attached to clothing, fur, feathers, farm implements and vehicles (DAFF 2001).

(c) Water
Answer: Yes

Comments: 
Appears to preferentially colonise areas of pooling water which suggests localised movement of seed by water (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

Water is a likely vector of long-distance dispersal (NT Weed Risk Assessment Technical Committee 2018).

(d) Wind
Answer: No

Comments: 
Seeds not adapted for long-distance dispersal by wind (NT Weed Risk Assessment Technical Committee 2018).

A4. How likely is long-distance dispersal by human-assisted means?

(a) Deliberate spread by people
Answer: Unlikely

Comments: 
Not likely to be deliberately spread by people in Australia (NT Weed Risk Assessment Technical Committee 2018).

(b) Accidentally by people and vehicles
Answer: Occasional

Comments: 
Its seeds can be spread long distances by accident, attached to clothing, fur, feathers, farm implements and vehicles (DAFF 2001).

(c) Contaminated produce
Answer: Occasional

Comments: 
Its seeds can be spread long distances by accident, attached to clothing, fur, feathers, farm implements and vehicles (DAFF 2001).

The Darwin infestation was most likely as a result of long-distance dispersal as a contaminant of potted plants (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

(d) Domestic/farm animals
Answer: Occasional

Comments: The mucous coat of the anthocarp shows a distinct sticky swelling when ripe, with which it clings to mammals and birds for wide dispersal. (Schmelzer 2006) 

Impacts

B1. What is the plant's competitive potential?
Answer: Low

Comments: 
Boerhavia erecta occurs in open bushland, on waste ground, in agricultural land and along roadsides, up to 1500(–2500) m altitude, usually on sandy or rocky soils. It prefers sunny localities and a seasonal climate with a pronounced dry season (Schmelzer 2006).

If left to become a monoculture it would be capable of shading out other ground cover species (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

In the Philippines uncontrolled populations of B. diffusa reduced maize yields by 70% (Pamplona et al. 1976) and uncontrolled B. erecta lowered soybean production 81% (Aquino & Pamplona 1981). Keeping soybeans weed-free of B erecta for 40 days gave maximum yields. Increasing crop density to 200,000 plants/ha did not reduce the competof B. erecta. This suggests little sensitivity to shading and is consistent with both species occurring as weeds in coffee, bananas, orchards and sugarcane (Aquino & Pamplona 1981, Holm et al. 1997, Pamplona et al. 1976).

B. erecta is a reported weed of 22 crops in 35 countries (Figure 13-4), especially in maize and cotton. It is a serious or principal weed of edible beans in Cuba; cotton in Kenya, Peru and Thailand; maize in Guatemala, Mexico, and Peru; and sugarcane in Indonesia and Peru (Holm et al. 1997).

In screenhouse studies in the Phillipines, application of N HFS fertiliser significantly increased seed production by 142% (from 3400-8250 seeds per plant). Application of NPS fertiliser significantly increased dry weight of plants by 35%. Application of nitrogen was not statistically significant for plant height (104-120 cm) (Libertino 1984).

In the Philippines, B. erecta is common in continuous maize production systems but not when maize is grown in the dry season and rice in the wet season (Holm et al. 1997, Pamplona & Madrid 1979).

B2. What is the plant’s potential to modify the existing fire behaviour and alter the fire regime?
Answer: No potential

Comments: 
No capacity to alter fire regimes (NT Weed Risk Assessment Technical Committee 2018).

B3. What is the plant’s potential to restrict the physical movement of people, animals, vehicles, machinery and/or water?
Answer: None

Comments: 
Perennial herbs, decument to erect, up to 60 cm tall (Chen & Wu 2007).

No capacity to restrict movement (NT Weed Risk Assessment Technical Committee 2018).

B4. What is the plant’s potential to negatively affect the health of animals and/or people?
Answer: None

Comments: 
In West and East Africa the leaves are sometimes eaten as a vegetable or used for the preparation of sauces. Cattle in the Sahel graze the plant before the inflorescences have developed. At this stage it can be made into silage as well. In Benin Boerhavia erecta was found to be very palatable for rabbits (Schmelzer 2006).

Used for pig fodder in the Americas (DAFF 2001).

Widely used in the Americas, India and Africa for human nutrition as vegetable. Also used as a medicinal plant for a wide range of maladies including malaria, hepatic disorders, jaundice, scabies, high blood pressure and wounds (Holm et al. 1997, Stintzing et al. 2004, Struwig & Siebert 2013).

Boerhavia erecta has similar properties to Boerhavia diffusa L., and the root is applied in India especially as a diuretic, but also as a stomachic, cardiotonic, hepatoprotective, laxative, anthelmintic, febrifuge, expectorant and, in higher doses, as an emetic and purgative. As a diuretic it is useful in cases of strangury, jaundice, enlarged spleen, gonorrhoea and other internal inflammations. In moderate doses it is successful in treatment of asthma (Schmelzer 2006).

B5. Does the plant potentially have negative effects on natural and cultural values?

(a) Reducing habitat quality for native animals?
Answer: No

Comments: 
Infestations would reduce crop yields and horticultural production in northern Australia, and damage natural ecosystems (DAFF 2001).

This American species is a widespread and sometimes serious weed in Australia’s neighboring tropical countries, particularly in annual crops. As such B. erecta had been included on the Northern Australia Quarantine Strategy (NAQS) target weed list as a species that is likely to arrive in Australia and potentially impact domestic agriculture and the environment (Westaway et al. 2018).

(b) Threatened species or communities
Answer: None identified

Comments: 
No threatened species or ecological communities are likely to be impacted (NT Weed Risk Assessment Technical Committee 2018).

(c) Sites of natural or cultural significance
Answer: None identified

Comments: 
No recognised sites of natural or cultural significance are likely to be affected (NT Weed Risk Assessment Technical Committee 2018).

B6. Is the plant presumed to have negative effects on environmental health?

(a) Soil chemistry/stability
Answer: No

Comments: 
No effect on soil chemistry or health reported.

(b) Water quality
Answer: No

Comments: 
No effect on water quality reported.

(c) Hydrology
Answer: No

Comments: 
No effect on hydrology reported.

Potential distribution

C1b. What is the Climatch suitability score (which indicates the proportion of the NT environment that is suitable for the plant)?
Answer: 10

Comments: 
Boerhavia erecta originates from the New World but now has a pantropical distribution. It occurs throughout the regions of tropical Africa with a distinct dry season, from West Africa east to Somalia and south to South Africa (Schmelzer 2006).

Widely distributed in Asia, Africa, the Pacific Islands, and South America (Holm et al. 1997).

The Climatch model determined that 100% of the Northern Territory is climatically suitable for the growth of Boerhavia erecta (BRS 2008, GBIF 2018, NT Weed Management Branch 2018).

Both species [B. diffusa and B. erecta] have the C4 pathway (Das and Santakumari 1978) giving them a high water use efficiency and explaining their adaptation to sandy soils and dry regions (Das & Santakumari 1977, Holm et al. 1997).

This species often has a thickened, semi-tuberous root, which may account in part for its tolerance to dry conditions (Holm et al. 1997).

C2. How many broad habitat types in the NT will the plant potentially naturalise in (up to 5)?
Answer: Five or more

Comments: 
In Darwin, Boerhavia erecta successfully invaded areas adjacent to a seasonal creek (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

The plants of the species grow in open areas with arid or sandy soil, revealing its status as a pioneer species. This weed species can be expected to occur along [the] railroad of the lowland of the whole island in near future (Chou et al. 2004).

The broad habitat types that Boerhavia erecta could potentially naturalise in include: 
- Tropical riparian 
- Tropical open forests 
- Beaches 
- Mitchell grasslands 
- Spinifex grass lands 
- Arid and semi-arid woodlands 
- Arid and semi-arid shrublands 
- Arid riparian 
The favoured habitat type was determined to be tropical open forests (NT Weed Risk Assessment Technical Committee 2018).

The species grows in well-drained stony, gravel, sand, loam or clay soil in riverbeds, on plains, mountain slopes or hillsides and ridges, often along roadsides, in shade to full sun at altitudes of 250–1250 m. Compared to other species of the genus, B. erecta prefers soil with the high levels of N, Ca (61,800 mg/kg) and Ti (1 170 mg/kg) (Struwig & Siebert 2013).

C3. What is the potential of the plant to occur throughout its favoured habitat in the NT (as identified in question 2)?
Answer: Incidental

Comments: 
Could occur incidentally throughout the habitat (NT Weed Risk Assessment Technical Committee 2018).

Control costs

A1. How detectable is the weed?

(a) Distinguishing features
Answer: Non-descript

Comments: 
Erect tar vine is a spreading broadleaved herbaceous plant to 1 m tall. It has a strong taproot and sticky, reddish stems. Dense infestations have a reddish haze above them caused by the erect flowering stems. Clusters of small white or pale pink flowers produce club-shaped, ribbed, sticky seeds (DAFF 2001).

This species is characterized by its opposite leaves, white to light pink flowers, and the five transverse ribs on the non-glandular fruits (Holm et al. 1997).

For someone who knows what they are looking for, it is quite distinct. The seedling leaves have purple-undersides and this feature persists to mature plants. If you weren't looking for the plant specifically, you wouldn't distinguish it from other plants (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

Requires specialist knowledge to identify (NT Weed Risk Assessment Technical Committee 2018).

The betalains are responsible for the red appearance of members belonging to the Amaranthaceae and Nyctaginaceae, such as A. spinosus and B. erecta (Stintzing et al. 2004).

(b) Active growth period
Answer: 4-8 months

Comments: 
Boerhavia erecta can be found flowering and fruiting throughout the year, when sufficient water is available (Schmelzer 2006).

It is not actively growing in Darwin during the dry season (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

(c) Height at maturity
Answer: <0.5 m

Comments: 
Perennial herbs, document to erect, up to 60 cm tall (Chen & Wu 2007).

Annual to short-lived perennial herb up 1 m tall, sometimes with a thick taproot (Schmelzer 2006).

In Darwin, mostly up to 0.5 m. Occasionally plants might reach 0.6 m (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

A2. What is the general accessibility of infestations at the optimum treatment time?
Answer: High

Comments: 
Easy to access infestations by walking and vehicle. Plants prefer open, sunlit areas (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

The plants of the species grow in open areas with arid or sandy soil, revealing its status as a pioneer species (Chou et al. 2004).

A3. How expensive is control of the weed in the first year of targeted control, for an infestation that has reached maximum weed density?

(a) Chemical costs
Answer: Very low

Comments: 
Minimal chemical use required - most of the time is spent looking for plants (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

(b) Labour cost
Answer: Very low

Comments: 
Average 2 hours per visit to look for plants at the eradication site. About 10-12 visits required during the active growing season (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

(c) Equipment cost
Answer: Very low

Comments: 
A backpack spray unit is used for control (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

A4. What is the general community perception of this weed within the region?
Answer: Low

Comments: 
Most people in the community would be unaware of this weed in the region (NT Weed Risk Assessment Technical Committee 2018).

Current distribution

B1. What is the current pattern of the species’ distribution across the weed management region?
Answer: Restricted

Comments: 
B. erecta appears to be confined to a single rural property near Darwin and prospects of eradication of this fast growing weed are promising due to the early response and collaborative effort between government departments and affected landholder (Westaway et al. 2018).

Persistence

C1. How long will it take to reach the maintenance period?
Answer: Medium

Comments: 
Boerhavia erecta can be found flowering and fruiting throughout the year, when sufficient water is available (Libertino 1984).

We reduced the original infestation to about 20 plants (mixture of juveniles and adults) after 1 year, and expect to achieve maintenance period at the end of the second year (B. Lukitsch, NT Weed Management Branch, pers. comm. 12/6/2018).

C2. What is the minimum time period for reproduction of sexual or vegetative propagules?
Answer: <1 growing season

Comments: 
Under favourable conditions, flowering starts 2 weeks after germination and the first seeds ripen 2 weeks later (Schmelzer 2006).
 
First matured seeds were observed at 22 days after seedling emergence (Libertino 1984).

C3. What is the maximum longevity of sexual or vegetative propagules?
Answer: 2-5 years

Comments: 
In screenhouse studies, highest germination of 26.0% was attained when seeds were sown on the soil surface in pot. The germination decreased as planting depth was increased (Libertino 1984).

[For B. diffusa] by the end of a long rainy season, 66% of the seed had emerged, but some emergence occurred after four cropping cycles (2 yr). Similar studies with B. erecta found that the emergence of 6-month-old seed peaked between 20 days after planting but continued through 60 days. Under field conditions, this behaved similarly to B. diffusa: 59% of the seeds emerged after one season and germination continued for more than 2 yr (Holm et al. 1997).

Germination of B. erecta seeds improved as storage time increased to 12 months but then declined (Popay 1973).

Seed coat removal enhanced germination (Holm et al. 1997, Popay 1973).

C4. What is the threat of reinfestation from outside the management region?

(a) Long-distance (>100m) dispersal by natural means
Answer: Rare

Comments: 
Its seeds can be spread long distances by accident, attached to clothing, fur, feathers, farm implements and vehicles (DAFF 2001).

(b) Long-distance (>100m) dispersal by human means
Answer: Rare

Comments: 
Its seeds can be spread long distances by accident, attached to clothing, fur, feathers, farm implements and vehicles (DAFF 2001).

Erect tar vine could enter Australia as a contaminant of clothing and footwear (DAFF 2001).

References

Aquino M & Pamplona P (1981 ). The influence of population density and some weeding practice on the yield of soybean. Weed Sci. Soc. Philippines. News/. 9:7. BRS (2008) Climatch. Australian Government Bureau of Rural Sciences. <http://data.daff.qov.au:8080/Climatch/climatch.jsp>. Accessed 10 June 2018. Chen S-H & Wu M-J (2007). A Taxonomic Study of the Genus Boerhavia (Nyctaginaceae) in Taiwan. Taiwania 52: 332-342. Chou, F-S, Liu, H-Y, Sheue, C-R, 2004. Boerhavia erecta L. (Nyctaginaceae), a new adventive plant in Taiwan. Taiwania 49: 39-43. DAFF (2001) . Northern Australia Quarantine Strategy Quarantine Handbook: essential information for residents of northern Australia. Australian Government Department of Agriculture, Fisheries and Forestry, Canberra. Das V & Santakumari M (1977) . The incomplete evolution of C4-photosynthesis within the pantropical taxon, Boerhavia : Nyctaginaceae. Photosynthetica 12418-422. GBIF (2018) . Global Biodiversity Information Facility, Boerhavia erecta. From: GBIF.org (12 June 2018) GBIF Occurrence Down load < https://doi. org/1 0.15468/d I. hfa54 7>. Holm L, Doll J, Holm E, Pancho J & Herberger J (1997). World weeds: natural histories and distribution. John Wiley & Sons. More references available at: https://territorystories.nt.gov.au/10070/373016