Home  //  News  //  Weed of the Moment  //  Angled Onion - Allium triquetrum

Angled Onion small groupA familiar sight (and odour) around the Dandenong Ranges in mid-winter to early spring is the appearance of the weed Allium triquetrum, common name Angled Onion.

It is often called onion weed due to it’s strong accompanying odour of onions, but technically this is incorrect, although it is known officially by this name in New Zealand.

Part of the lily family, it is a native of the Mediterranean but has managed to thrive in the Dandenongs thanks to the abundance of damp semi shaded areas along stream banks, roadsides and bushlands.

Angled Onion is considered an environmental weed because it smothers and displaces indigenous grasses and groundcovers impacting the processes of bush regeneration.

Description: A green three cornered flower stalk with a white trumpet shaped flower at the top of each stalk which grows in clumps.

Dispersal: It spreads in two ways - seed dispersal from the white flowers and bulb reproduction below ground.

Treatment: Knowledge of the life cycle is the easiest way to understand the best ways to treat Angled Onion.

Green shoots grow from food stored in bulbs underground which in turn allow the formation of seed producing flowers. Interrupting the process by which the seeds are formed is the most effective strategy.

Life Cycle Angled OnionSlashing:  Cutting the green shoots as soon as they appear above ground will start to exhaust the bulbs and slow down the growth cycle.  Repeated slashing will exhaust the reserves in the bulb so that it is unable to keep producing shoots and eventually flowers. Adding dense mulch will also help. It can sometimes take several seasons to finally achieve success.

Hand Removal:  While the ground is moist in winter this can be effective although time consuming. By the time the flowers have appeared, the bulbs have reproduced under the ground so that hand removal becomes largely ineffective as many smaller bulbs may be left behind.

Spraying:  Spraying with a glyphosate based product is best done just prior to or when the flowers are formed. This targets the seeds and stops them being distributed.

Summer Collection:  Oddly enough, removing Angled Onion bulbs is possible over the summer months. As the surface ground dries out, the bulbs become visible just below the surface and can be collected.

Biological Control is also a future method of control:  https://link.springer.com/article/10.1007/s13313-014-0279-6