Three-Cornered Garlic (Allium triquetrum)

Photo: © Auckland Museum CC BY

Family: Alliaceae

Growth Habit: Three Cornered Garlic has a tuft of soft basal leaves, 2-11 in number (usually 2 or 3),  arising annually in late winter from a small, pale bulb. The 3-angled, strap like green leaves, somewhat succulent, grow to an average height of 30 to 50 cm and have a characteristic ‘onion’ or ‘garlic’ smell when crushed. The flowering stem, also distinctly 3-angled, is unbranched and topped by a cluster of white drooping bell-like flowers. Roots have white or pale egg shaped bulbs 5-15 mm diameter, with a transparent covering membrane. The outer layers consisting of the swollen bases of the leaves. Initially fleshy and becoming hard in summer. There may be a few to many bulblets. The feeder roots are fibrous, short, shallow and spreading.

Type of Plant: A bulbous perennial.

Photo: (c) Tigerente GFDL + CC-BY SA licenses

Flowers: The drooping, showy flowers are on slender stalks and have 6 white petals that are 1-2 cm long and each petal has a prominent green midline. Flowering occurs through spring.

Fruit/Seed: Fruit are about the size of a small pea. Green, globular to egg shaped capsule, 4-7 mm long, hanging in clusters. Seeds are black with a conspicuous whit spot on one end. Oblong and 2-5 mm long.

Dispersal: It reproduces by seed or bulbs.

Distribution: Found along roadsides, wasteplaces and highly cultivated areas in south-east Australia.

Status: Noxious weed. Secondary weed in Tasmania.

Weed Impact:

  • Can taint milk and meat, however stock tend to avoid it due to its onion-like flavour.
  • Capable of forming dense colonies on grassland and moist areas excluding native vegetation.
  • Smell might be offensive in the garden.

For further information contact the Department of Primary Industry, Parks, Water and Environment, Tasmania.

Control Methods:

  • Avoiding soil from infested areas.
  • At a minimum, remove flowers to stop seed formation.
  • Grubbing. Remove manually and ensure all bulbs are removed otherwise the plant will reshoot. Dispose of weeds appropriately, squashing bulbs can help reduce germination.
  • Herbicide. Spot spray. Herbicides registered in Tasmania include dicamba, MCPA, metsulfuron and glyphosate.

N.B. Always check the herbicide label before use.