For the identification of insects and other fauna and flora of South Africa.

Wednesday, July 10, 2013

Lime Yellow Pea/Horsegram (Macrotyoma axillare)

Family Fabaceae
This plant has become very invasive in Kruger National Park ans in some areas cover all the vegetation.
Origin
Native to large parts of Africa (i.e. Kenya, Tanzania, Uganda, Burundi, Cameroon, Rwanda, Zaire, Ghana, Guinea, Nigeria, Sierra Leone, Togo, Angola, Malawi, Mozambique, Zambia, Zimbabwe, Botswana, Namibia, South Africa and Swaziland) and the Arabian Peninsula (i.e. Yemen).

 Cultivation

Perennial horse gram (Macrotyloma axillare var. axillare) has been widely cultivated as a pasture legume in the warmer parts of Australia, particularly in northern New South Wales and southern Queensland. The cultivar 'Archer' is the only variety sold commercially in Australia for this purpose.

 Habitat

This species prefers fertile soils in tropical and sub-tropical regions. It is a weed of roadsides, fences, disturbed sites, open woodlands, grasslands, highland pastures, parks and gardens.

 Distinguishing Features

 a long-lived trailing or climbing vine with stems covered in close-lying hairs.

 its compound leaves have three leaflets that are hairy on both surfaces.

 its greenish-yellow pea-shaped flowers are arranged in small clusters in the leaf forks.

 its elongated pods (3-5 cm long and about 7 mm wide) are hairy and have a pointed tip.

 Habit

A trailing or climbing vine with stems usually growing up to 3.5 m long (occasionally up to 10 m in height), that are produced from a long-lived (i.e. perennial) woody rootstock.

Reproduction and Dispersal
This species reproduces by seed and has been deliberately spread as a pasture legume. It is probably also dispersed as a contaminant of agricultural produce (e.g. fodder and pasture seeds).

 Impacts

Perennial horse gram (Macrotyloma axillare var. axillare) is regarded as an environmental weed in Queensland. This species has become a serious weed in open forests and woodlands, where it climbs on woody plants and affects the regeneration of native species. It is currently of most concern in south-eastern Queensland, where it is rapidly spreading and ranked among the top 200 most invasive plant species.

Perennial horse gram (Macrotyloma axillare var. axillare) appears on several local environmental weed lists in this region (e.g. in Redlands, Maroochy, Cooloola and Caboolture Shires) and is invading native vegetation near Mount Emu on the Sunshine Coast. This area includes the habitat of most remaining populations of the endangered Mount Emu she-oak (Allocasuarina emuina). Perennial horse gram (Macrotyloma axillare var. axillare) is also becoming a concern in central Queensland (e.g. in the Burnett Shire) and far northern Queensland, where it is listed as a priority weed species.
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