Southern threecornerjack

Emex australis

Emex australis, commonly known as doublegee or three-corner jack, is a flowering plant species native to Australia and New Zealand. It belongs to the Polygonaceae family and is known for its distinctive three-cornered fruits that contain sharp spines. Doublegee is considered a weed in some regions due to its ability to colonize disturbed areas and compete with other vegetation. Here is an informative description of Emex australis, including its appearance, habitat, and management:

Description:

  • Growth Form: Doublegee is an annual herbaceous plant that grows low to the ground, forming dense mats.

  • Leaves: The leaves are alternate, simple, and often have a distinct three-lobed shape. They can be green or reddish in color.

  • Stems: The stems are prostrate and branched, spreading horizontally along the ground.

  • Flowers: The flowers are inconspicuous and greenish, arranged in clusters on short spikes.

  • Fruits: The most characteristic feature of doublegee is its fruit, which is a three-cornered capsule. Each capsule contains three seeds, and each seed is covered in sharp spines.

Habitat:

Doublegee is commonly found in disturbed areas, including agricultural fields, roadsides, and waste areas. It thrives in sandy or well-drained soils and can tolerate a range of environmental conditions.

Identification:

Identifying Emex australis involves recognizing its key features:

  1. Three-Cornered Fruits: The most distinctive feature is the three-cornered capsules that contain sharp spines.

  2. Three-Lobed Leaves: The leaves are often three-lobed, contributing to the common name "three-corner jack."

  3. Prostrate Growth: The plant grows low to the ground, spreading horizontally.

  4. Green or Reddish Leaves: The leaves can be green or reddish in color.

Management:

Doublegee is considered a weed in certain regions, and its sharp-spined fruits can be a nuisance in areas frequented by people and animals. Management strategies may include:

  1. Cultural Control: Promoting the growth of competitive vegetation can help suppress the spread of doublegee.

  2. Mechanical Control: Mowing or slashing can be effective in reducing the height of the plants and preventing seed production.

  3. Herbicides: Selective herbicides may be used for targeted control, but care must be taken to avoid harm to desirable vegetation.

  4. Prevention: Implementing preventive measures, such as practicing good weed hygiene and minimizing soil disturbance, can help prevent the establishment of doublegee.