Spiny emex, Three corner jack, Doublegee
| Botanical Name | Emex australis |
|---|---|
| Family | Polygonaceae |
| Origin | Southern Africa |
Identification
Spiny emex is a hairless semi-prostrate annual herb which develops a stout taproot. Leaves form a rosette in early growth and branch later. The leaves are very similar to dock leaves in shape. Flowers are inconspicuous and are produced in clusters in between the leaf stems. These develop into burs that change from green to brown as they ripen. The burs are woody, about 7 mm long and each bur has three sharp spikes. When the burs are shed they lie with one spike always pointing upwards.Habitats
Usually found in temperate regions, mainly in sandy or loam soils near the coast. Spiny emex can become a weed in pasture, crops, lawns and waste places. In the Bay of Plenty it has been found in the Maketu area.Impact to Biota and Ecosystems
Spiny emex competes with pasture and crops. Competition is usually for nitrogen, significantly reducing yields. Spiny emex has been responsible for sheep deaths in Western Australia due to oxalic acid poisoning. The burs can cause discomfort in humans and lameness in animals.Dispersal Routes, Vectors, Infestation Sources
The burs are well equipped for dispersal as one spike always points upward attaching to shoes, tyres, the feet of animals or almost anything that passes over or is placed on it. It can be dispersed in fodder crops like hay and the burs will float on water, spreading along water courses.Management
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Management |
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| Physical Control |
Grub out isolated plants. |
| Disposal |
If plants are seeding, burn. |
| Chemical Control |
Spot spray with Glyphosate at a rate of 100 ml/15 L of mix. As this herbicide is non-selective, care needs to be taken to ensure that no spray drifts on to any non-target plants |
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Biological Control |
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| Recommended Approach | |