Australian Plant Census (2011) available at: Vascular Plants APNI (biodiversity.org.au)
Pannicle Jointvetch (Aeschynomene paniculata) is a leguminous subshrub or shrub 1–2.5 m tall, with tough, spindly, reddish-brown, striated (grooved) stems. Leaves are compound and about 4–9 cm long. 40–80 single elliptic or oblong leaflets are arranged on 2-sides of the main leaf axis but without a terminal leaflet. The leaflets are sensitive to the touch.
The pea-shaped flowers are yellow, numerous and 6–7 mm long and are on stalks up to 10 mm long. The seed pods are stalked, straight or slightly curved and 15–22 mm long.
The upper margins of the pods (fruit) are shallowly indented, while the lower margins are strongly indented, with the indentations dividing each pod into 3–5 distinct sections called articles. The articles break free from each other when the pod matures (Lima 2006; Short 2007, pers. comm.).
For further information and assistance with identification of Pannicle Jointvetch contact the herbarium in your state or territory.
Pannicle Jointvetch is adapted to seasonally dry tropical areas (Csurhes 2016). It appears best suited to areas with 800–1000 mm per annum and can tolerate partial shade but seems to prefer full sun.Preferred soil types appear to be sandy to silty loam soils, sometimes with a clay sub-soil (Csurhes 2016).
Pannicle Jointvetch may be confused with other species of Aeschynomene. Of the other species in Australia only A. aspera and A. indica, like Pannicle Jointvetch, have leaflets with one main nerve (midvein), all others have two or more conspicuous lateral nerves. In A. aspera the lower stems are spongy and the seed pods are more than 6 mm wide, with the 3-5 articles being corky and having rough margins. Plants of A. indica are sparsely to densely hairy and sometimes viscid and at maturity the articles of the fruit are strongly rugose (ridged and wrinkled), not smooth as with Pannicle Jointvetch (Reynolds 1990; Lima 2006).
Pannicle Jointvetch is one of seventeen sleeper weeds identified by the Bureau of Rural Sciences (following consultation with the Australian Weeds Committee) which could have nationally significant impacts on agriculture if allowed to spread.
Agriculture: It is reported that Pannicle Jointvetch can develop into thickets which exclude useful pasture species and that it is most likely to be a problem for woodland and rangeland pastures than in cropping or agriculture. Grazing woodland is the primary land use currently impacted by this species particularly where it has escaped pasture plant evaluation sites at Batavia Downs (Cunningham et al. 2004; Cunningham & Brown 2006).
Native ecosystems: In the areas where it has naturalised in Queensland it has spread rapidly, particularly in grasslands, dry Eucalyptus and Corymbia woodlands and seasonally wet Melaleuca woodlands, where the soil tends to be exposed each dry season (Csurhes 2016). Without any control, large numbers of seeds are dropped resulting in the development of more or less pure stands over a few years (Csurhes 2016).
Pannicle Jointvetch is said to produce abundant, long-lived seed but no information as to any particular method of spread has been noted (Cunningham & Brown 2006). Seeds can be dispersed through the gut of ruminants and readily establish in dung. In monsoonal areas, seeds are suspected to have been transported down-slope by heavy rain. Vehicles might also carry seeds embedded in mud (Csurhes 2016).
Pannicle Jointvetch was introduced into Queensland as a potential pasture species, trialed by the Queensland Department of Primary Industry. Due to the early shedding of leaves the species was deemed unsuitable as a fodder plant but it escaped from the experimental plots. Attempts to eradicate it from Batavia Downs on Cape York Peninsula appear to have had limited success (Cunningham et al. 2004; Cunningham & Brown 2006).
How the species arrived in the Northern Territory has not been unequivocally established but it seems likely that it is related to activities of the pastoral industry (Short 2007, pers. comm.).
Chemical control: Pannicle Jointvetch can be controlled with herbicides during active growth, just prior to seeds being produced in late summer, a period of opportunity that tends to be limited to 2–3 months in the Australian monsoon tropics (Csurhes 2016).
Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au.
Non-chemical control: Grazing: Grazing is not a useful form of control as it generally does not prevent seeding in North Queensland (Csurhes 2016). However, grazing can assist control in some situations, as it suppresses grass cover and makes detection feasible (Csurhes 2016). The maintenance of vigorous pasture generally slows establishment and spread of Pannicle Jointvetch (K. Cox, pers. comm. in Csurhes 2016).
Fire: appears to soften some seeds and destroy some mature plants, depending on the intensity of the fire and field experience in North Queensland has found that fire results in mass germination, with more than 500 seedlings recorded per square metre (K. Cox, pers. comm. in Csurhes 2016). Fire can be a useful tool to deplete the soil seed bank, provided the seedlings are treated soon after with herbicide (Csurhes 2016).
Pannicle Jointvetch reproduces from seeds, which are produced in considerable numbers and readily establish in uncultivated ground under summer-rain conditions (Csurhes 2016). Mature seeds can be produced in as little as four months after establishment from seed, or three months if re-growing from perennial plants and seeds often exhibit high levels of hard-seed dormancy (Csurhes 2016).
Pannicle Jointvetch is recorded in both Queensland and the Northern Territory. It is most widespread in Queensland, with sporadic occurrences along much of the east coast of the state. The largest infestation appears to be that at Batavia Downs on Cape York Peninsula. There are published records of small populations of this species at Birralee (Collinsville), Blue Mountain (near Mackay), Eungy (Mt Nebo), Glenfield (Sarina), Proserpine, Swans Lagoon (Ayr) and Koumala, while populations at Milgarra, Woodview, Mareeba and Mt Surprise may have been eradicated.
In the Northern Territory the species is only known by a single specimen collected in 2005 from Fogg Dam (near Darwin) (Cunningham & Brown 2006; Short 2007, pers. comm.).
Analyses using the modelling tool CLIMATE suggest that the species has the potential to spread through north-eastern Queensland, the northern Northern Territory and northern Western Australia (Cunningham et al. 2004; Cunningham & Brown 2006).
Pannicle Jointvetch is native to the Americas, including Mexico, Belize, El Salvador, Guatemala, Honduras, Guyana, Suriname, Venezuela, Brazil, Bolivia, Columbia and Paraguay. It is naturalised in Hawaii (GRIN 2007).
Not declared in any Australian state or territory.