Pacific Island Ecosystems at Risk (PIER)

Macroptilium bracteatum

RISK ASSESSMENT RESULTS: Low risk, score: -1

Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.
Information on Risk Assessments
Original risk assessment
  Macroptilium bracteatum (burgundy bean)   Synonyms: Phaseolus bracteatus Nees & Mart., Phaseolus decipiens Benth.  Family - Fabaceae Answer Score
1.01 Is the species highly domesticated? n 0
1.02 Has the species become naturalized where grown?    
1.03 Does the species have weedy races?    
2.01 Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical” 2  
2.02 Quality of climate match data (0-low; 1-intermediate; 2-high)                 see appendix 2 2  
2.03 Broad climate suitability (environmental versatility) y 1
2.04 Native or naturalized in regions with tropical or subtropical climates y 1
2.05 Does the species have a history of repeated introductions outside its natural range?  y=-2 y  
3.01 Naturalized beyond native range         y = 1*multiplier (see Append 2), n= question 2.05 n -2
3.02 Garden/amenity/disturbance weed                              y = 1*multiplier (see Append 2) n 0
3.03 Agricultural/forestry/horticultural weed                         y = 2*multiplier (see Append 2) n 0
3.04 Environmental weed                                                     y = 2*multiplier (see Append 2) n 0
3.05 Congeneric weed                                                          y = 1*multiplier (see Append 2) y 2
4.01 Produces spines, thorns or burrs n 0
4.02 Allelopathic n 0
4.03 Parasitic n 0
4.04 Unpalatable to grazing animals n -1
4.05 Toxic to animals n 0
4.06 Host for recognized pests and pathogens n 0
4.07 Causes allergies or is otherwise toxic to humans n 0
4.08 Creates a fire hazard in natural ecosystems n 0
4.09 Is a shade tolerant plant at some stage of its life cycle    
4.1 Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island) y 1
4.11 Climbing or smothering growth habit y 1
4.12 Forms dense thickets n 0
5.01 Aquatic n 0
5.02 Grass n 0
5.03 Nitrogen fixing woody plant n 0
5.04 Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers) n 0
6.01 Evidence of substantial reproductive failure in native habitat n 0
6.02 Produces viable seed. y 1
6.03 Hybridizes naturally n -1
6.04 Self-compatible or apomictic y 1
6.05 Requires specialist pollinators n 0
6.06 Reproduction by vegetative fragmentation n -1
6.07 Minimum generative time (years)                 1 year = 1, 2 or 3 years = 0, 4+ years = -1 1 1
7.01 Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas) n -1
7.02 Propagules dispersed intentionally by people y 1
7.03 Propagules likely to disperse as a produce contaminant n -1
7.04 Propagules adapted to wind dispersal n -1
7.05 Propagules water dispersed n -1
7.06 Propagules bird dispersed n -1
7.07 Propagules dispersed by other animals (externally) n -1
7.08 Propagules survive passage through the gut n -1
8.01 Prolific seed production (>1000/m2) y 1
8.02 Evidence that a persistent propagule bank is formed (>1 yr) n -1
8.03 Well controlled by herbicides    
8.04 Tolerates, or benefits from, mutilation, cultivation, or fire y 1
8.05 Effective natural enemies present locally (e.g. introduced biocontrol agents)    
  Total score:   -1

Supporting data:

  Notes Reference
1.01 No evidence that the cultivated species is substantially different from the plants occurring in the wild.  
1.03 "Two cultivars have been registered (Cadarga and Juanita). Cardarga has an erect form and is consistently high yielding, but it can be affected by bean mosaic virus in wet years. Juanita is more decumbent; although slightly less productive, it does not appear to be affected by the mosaic virus. Blends of both varieties may be marketed under a brand name by the seed company holding marketing rights." "It is therefore essential to allow seed drop of both cultivars, but especially 'Cadarga', for burgundy bean persistence.  Although 'Juanita is strongly perennial , 'Cadarga'  is less so and relies far more upon seed production and seedling recruitment to persist." ly
2.01 "Native to:
South America:  Argentina (Salta, Jujuy, Formosa), Bolivia (Santa Cruz), Brazil (Bahia, Minas Gerais, Sao Paulo), Paraguay, Peru (La Libertad), Venezuela (Anzoategui)."
2.02 Introduced to the U.S. mainland, Hawaii, Puerto Rico and Virgin Islands.
2.03 "M. bracteatum has mostly been collected between about 10 and 27°S, and up to 12°N.  It occurs at >1,200 m asl at  24°S (average annual temperature 17.5°C) to lower altitude areas with average annual temperature of 25°C.  It germinates and commences growth at lower temperatures than many other tropical and subtropical legumes.  If moisture is available, it germinates and commences regrowth some weeks earlier than C. ternatea in spring in the subtropics.  In the higher latitude subtropics where early spring rains can often occur, this is one of its most valuable characteristics.  In addition to its capacity to grow in cooler temperatures, M. bracteatum has been used successfully in pasture areas that typically have high summer temperatures (>35ºC)."
2.04 "Native to:
South America:  Argentina (Salta, Jujuy, Formosa), Bolivia (Santa Cruz), Brazil (Bahia, Minas Gerais, Sao Paulo), Paraguay, Peru (La Libertad), Venezuela (Anzoategui)."
2.05 (1)Introduced to the U.S. mainland, Hawaii, Puerto Rico and Virgin Islands.  (2)Introduced to South Africa. (1)  (2)Mokoboki, H. K.; Ndlovu, L. R.; Ayisi, K. K. Chemical and physical parameters of forage legume species introduced in the Capricorn region of Limpopo Province, South Africa. South African Journal of Animal Science 32 (4) : 247-255 2002
3.01 No evidence of naturalization  
3.02 No evidence  
3.03 No evidence - Also - "Burgundy bean is readily eaten and can produce liveweight gains of up to 1 kg/day. It rarely lasts more than 4 years under grazing. Although there is strong seedling regeneration each year over a short period, most of the seed is soft. Because of this low proportion of hard seed, burgundy bean is unlikely to become a serious weed of subsequent crops."
3.04 No evidence - Also "Ability to spread  - Has the ability to spread through pod dehiscence and high seed yields but high palatability results in little spread outside of sown paddock."
3.05 (1)The invasive, dark purple-flowered weed, ‘Black Pea’ or ‘Siratro’ (Macroptilium atropurpureum) is a serious problem in parts of Minyirr Park and elsewhere in the Shire of Broome. Although the Black Pea is now pan-tropical, it is native to tropical America (p.158, Broome and Beyond….).
If systematic control and eradication measures are not implemented, the coastal vegetation of Minyirr Park will become seriously degraded. Already, a large area of monsoon vine-thicket vegetation in Minyirr Park is overgrown with Black Pea, smothering native trees and shrubs. Being deep-rooted, the Black Pea is particularly tenacious once established in a locality. (2)Indooroopilly Island
Conservation Park:Weeds are a major problem on the park. Invasive grasses and other ground
covers such as molasses grass, Melinis minutiflora and siratro Macroptilium
atropurpureum are preventing native species, including canopy trees, from
(1) (2)
4.01 No evidence of such structures.
4.02 No evidence  
4.03 No evidence  
4.04 "M. bracteatum is extremely palatable and is preferentially grazed.  Consequently, grazing management in pastures with a high percentage of burgundy bean will require periods of spelling.  In the short term, individual plants have the capacity to regrow rapidly, although under longer term grazing, burgundy bean plant density  usually declines, especially when a component of a grass dominant pasture. ... "Unlikely to have weed potential despite high seed yields.  Hard seed breaks down far more rapidly than many other tropical and subtropical legumes, and the species is very palatable at all stages of maturity."
4.05 "Toxicity - None recorded.  Burgundy bean does not cause bloat."
4.06 (1)"Pests and diseases - No major problems although both cultivars can show leaf symptoms of bean mosaic virus.  This appears to have little effect on productivity.  It is susceptible to bean fly (Ophiomyia phaseoli), the green vegetable bug (Nezara viridula) and a range of flower-eating caterpillars in northern Australia.  Insect control during flowering and seed set is critical in seed crops."   (2)Burgandy bean is a host to Phakopsora pachyrhizi - which is also infects 31 species in 16 genera of legumes and 60 species in other 26 genera.
4.07 No evidence  
4.08 (1)"Fire - No information available" (2)Probably not - low growing trailing herbaceous perennial.
4.09 "Light
No information available.
4.1 "Mostly collected from light to medium textured soils, but adapts well to heavy clays.  While the pH of these soils has most often been near neutral to alkaline, it has also been collected on soil of pH 4.5.  The key soil characteristic required for M. bracteatum is a slightly acid to alkaline soil reaction .  Despite the range of light textured soils at the point of collection, M. bracteatum was selected for use on heavy textured soils which are invariably alkaline at and near the surface. ... "Suitable on a wide range of soil textures."
4.11 (1)"Erect and trailing pubescent herbaceous perennial."   (2)Herb with climbing stems. (1)  (2)
4.12 No evidence  
5.01 "Erect and trailing pubescent herbaceous perennial."
5.03 Nitrogen fixing herbaceous legume [not woody] -  "… The quantity of nitrogen derived from fixation was correlated with above-ground dry matter and nitrogen content. There was a significant (P lt 0.05) growth response by wheat following legumes compared with that following sorghum in the increasing order V. radiata = M. atropurpureum = L. purpureus gt C. cajan = M. saliva = V. trilobata = M. bracteatum = G. latifolia gt S. scabra = D. virgatus = C. ternatea. Previous legume growth had no significant (P gt 0.05) effect on yield or nitrogen concentration in a second 'plant-back' crop (sorghum). It was concluded that a wide range of pasture-ley legumes have the potential to improve cereal crop production in this region." Armstrong, R. D.; McCosker, K. J.; Millar, G. R., et al. Improved nitrogen supply to cereals in Central Queensland following short legume leys
Australian Journal of Experimental Agriculture 37 (3) : 359-368 1997
6.01 "The espartillo-grasslands present a wealth of native legumes as soon as fire frequency is reduced and disturbance by grazing increased. Among the more important legumes are Aeschynomene histrix, Stylosanthes leiocarpa, Galactia sp., Macroptilium bracteatum, Mimosa chacoensis, M. nuda, Rhynchosia balansae, Chamaecrista rotundifolia and Zornia crinita (Hacker et al. 1996). "
6.02 (1)"Germination is rapid and the seedlings grow quickly to get ahead of most sown grasses."  (2)Optimum temperature range for germination up to 36 degree celcius. (1)  (2)
6.03 Probably not - No evidence of hybridization in the genus Macroptilium.  
6.04 (1)"Primarily self-pollinating."  (2)"Abstract: Flower phases and flower visitors of Macroptilium bracteatum (Nees and Martius) Marechal and Baudet were studied in Parque Rivadavia (Concordia, Entre Rios province, Argentina). Three flower phases were recognized from flower opening to wilting (24 hs). The stigma is receptive during phases one and two. Pollen reacts positively to peroxidases in all phases, its viability is 82% and its main cytoplasmic reserve is starch. Pollenkitt contains lipids and proteins. Nectar is present in all three phases. Among the six flower visitors observed, Bombus atratus Franklin (dominant) and Centris sp. (rare) triggered the pollen transferring and stigma exposing mechanism (nototribic). The development of the ovary and of the pollen tubes in flowers isolated for 24 and 48 hs. as well as the analysis of the P/O relationship and fructification under controlled conditions suggest that this species is a facultative xenogamous." (1)  (2)Brizuela, Maria M.; Hoc, Patricia S.; Di Stilio, Veronica S., et al. Floral biology of Macroptilium bracteatum (Leguminosae, Phaseoleae) Darwiniana (San Isidro) 32 (1-4) : 41-57 1993
6.05 Probably not - "Abstract:  The genus Macroptilium (Benth.) Urban is characterised by having asymmetrical flowers and spirally coiled styles. The pollen is presented secondarily by a stylar brush. Floral structures of four species were analysed at macroscopical and microscopical levels as to their role in floral functioning.
The vexillum has two auricles with globose and striate epidermic cells. In all species investigated, wing and keel petals are neatly connected at their bases. The distal parts of the keel form kind of an application tube and the petals are fused to each other by rows of striate interpenetrating trichomes along their upper edges and by genuine fusion along their lower side.
Macroptilium has a ring-shaped nectary, narrow and lobed asymmetrically. It is located between the base of the ovary and the staminal furrow, and is attached to the receptacle. Nectar, which is secreted trough open stomates, collects between the nectary and the staminal furrow.
We conclude that the four species studied have floral structures fitting into the melittophily syndrome." [Probably not - tupical pea flower].
6.06 "Has the ability to spread through pod dehiscence and high seed yields but high palatability results in little spread outside of sown paddock." [Ref suggests that the species does not spread by vegetative means].
6.07 (1)"In the southern hemisphere, reproductive development usually commences in February after sowing in November with peak flowering in March and April, with about 50–90 days from sowing to flowering…. "Seed can be harvested 6–8 months after sowing. "  (2)short-lived perennial giving 2–3 year’s growth (1)   (2)
7.01 Probably not - not grown in heavily trafficked areas.  
7.02 "Uses/applications  -  M. bracteatum was selected for use as a short-term pasture plant on heavy textured alkaline soils in the subtropics.  It replaces the more tropically adapted butterfly pea (Clitoria ternatea ) in subtropical regions because of its greater tolerance of cooler temperatures.  It is also an alternative to lucerne (Medicago sativa ) in the subtropics."
7.03 "Burgundy bean forms good associations with grasses adapted to clay and clay loam soils, but because of its exceptional palatability, is difficult to maintain in pastures in significant amounts after 3–4 years.  For this reason it is considered a short-term phase legume rather than a plant for permanent pastures.  The rapid growth and establishment of burgundy bean means that it can be used in combination with butterfly pea (C. ternatea ) which is comparatively low yielding in its first year but can persist for much longer." - [It s grown with other pasture grasses and may be seed crops but the seed morphology is very different from that of grass seeds hence may be unlikely to be a contaminant].
7.04 "Ability to spread  - Has the ability to spread through pod dehiscence and high seed yields but high palatability results in little spread outside of sown paddock." [Suggest dispersal is by gravity -no evidence of adaptation to wind dispersal]
7.05 No evidence that the species naturally inhabits or grows near waterways.
7.06 Probably not - an herbaceous legume.
7.07 No evidence that the propagules have any means of attachment.
7.08 This species is hight palatable - the seeds are eaten but no evidence of spread after passing through animals gut. It seems seeds are digested by the animals.
8.01 "Fruit linear , 4–9 cm long with 9–17 seeds.  Seeds almost cylindrical, 2.5–4 mm long and 3–4 mm in diameter;  brown, black or tan in colour, almost always mottled;  c. 170,000 seeds/kg." [At the rate of 17 seeds per fruit - about 60 fruits per sq m would give > 1000 seeds/sq m - this seems possible given the photos of the habit of the plant on the ref website].
8.02 "Recently harvested seeds have a high level of hardseededness, although this breaks down rapidly in the soil.  Seed that has been harvested and stored should be checked for germinability prior to sowing, and, if it retains a high proportion of hard seed (e.g. >70%), should be mechanically scarified. ... "Unlikely to have weed potential despite high seed yields.  Hard seed breaks down far more rapidly than many other tropical and subtropical legumes, and the species is very palatable at all stages of maturity." [Probably not - hard seed coat breaks down rapidly].
8.03 No evidence that the species is being controlled for.  
8.04 "Abstract: Two promising ley legumes, Macroptilium bracteatum (CPI 27404) and Macrotyloma daltonii (CPI 60303), were compared under glasshouse conditions with the widely used Lablab purpureus cv. Highworth in terms of response to defoliation and nutritive value. Plants were grown for 5 weeks prior to cutting at 2-, 4- or 6-weekly intervals at 7 or 15 cm height. The treatments were applied over 12 weeks and compared with uncut controls. M. bracteatum was the most persistent and productive legume under frequent defoliation, producing more growing points than the other species when cut at 7 cm. It had the highest yields of roots under all cutting regimes and set seed under the most lenient regime. All M. daltonii plants died when cut at 7 cm, mostly after the initial cutting. Although survival was much better when cut at 15 cm, this species gave lower top-growth and root yields than M. bracteatum and L. purpureus. It set seed only under the most lenient cutting regime. L. purpureus outyielded the other 2 species in the uncut controls. However, the relative decline in top-growth yield with increasing severity of cutting was greater than for M. bracteatum. Half the plants died under the combination of frequent (2- or 4-week) and intense defoliation (7 cm). It did not flower during the experiment. The main difference in quality, as assessed by N%, P%, acid detergent fibre and grinding energy, was between leaf and stem. Differences in leaf or stem quality between the 3 species were relatively minor. Macroptilium bracteatum was identified as a productive legume more tolerant of severe defoliation than L. purpureus." Dalzell, S. A.; Brandon, N. J.; Jones, R. M. Response of Lablab purpureus cv. Highworth, Macroptilium bracteatum and Macrotyloma daltonii to different intensities and frequencies of cutting
Tropical Grasslands 31 (2) : 107-113 1997
8.05 Don’t know  

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