Triquetrum means three cornered and refers to the flowering stem and base of the leaf blade which are triangular in cross section.
Three-cornered Garlic is a translation of the Latin name and refers to the triangular stem and garlic odour of the plant.
Other Names:
Angled Onion
Onion Weed
Three-cornered Leek
Triquetrous Garlic
Triquetrous Leek
Summary:
Three-cornered Garlic has a tuft of soft basal leaves arising annually in late winter from a small, pale bulb. The 3-angled, strap like leaves may be up to 45 cm long 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. 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. The flower has 6 stamens and a style which is 3-branched at the tip.
Native to the Mediterranean Region, it is now found in damp areas, frequently near creeks or granite rocks around Albany and the south west and it is a potentially serious weed that is capable of dominating the understorey. It flowers in late winter and early spring.
Description:
Cotyledons:
One.
Leaves:
Strap like, light green, somewhat succulent with an onion like odour, 2-11 in number (usually 2 or 3) arising near the base of the stem and parting at the same height. Initially erect but soon become weeping.
Blade - 100-500 mm long by 3-20 mm broad, triangular near the base then flat or concave and keeled on the underside. Somewhat fleshy with 9-15 lengthwise veins. Smooth edges. Hairless. Onion odour when crushed.
Sheath - Flat or slightly channelled, weak, 5-10 mm wide.
Stems:
Flower stem (scape) - Leafless, light green. 1 or more per cluster of plants. Triangular in section, 100-500 mm tall with basal leaves that part from the stem at the same height. Hollow. Erect at flowering and droops as fruit matures. Onion odour when crushed.
Flower head:
Loose umbel that is 35-75 mm diameter with 3-15 green striped, white, drooping flowers about 12 mm long, on stalks (pedicels) that are 15-30 mm long. The flower head is not globular or hemispherical.
Flowers:
White with a green stripe on the midline of each of the 6 'petals'. 10-20 mm long by 10-15 mm wide. Usually they all droop to one side.
Bracts - Flower buds are at first enclosed in two white papery bracts that split to reveal the umbel of flowers.
Ovary - 2 ovules per cell.
Style - 3 short recurved branches in the upper 1 mm.
Perianth - Narrowly bell shaped, 10-18 mm long. 6 segments with short sharp or obtuse tips, 3 broadly elliptical, and 3 a little narrower, white in colour with a central green stripe and each with a stamen attached towards the base.
Stamens - 6. Enclosed with simple filaments that are slightly broader at the base and 5-6 mm long by 0.5 mm wide. Shorter than perianth.
Anthers -
Fruit:
About the size of a small pea. Green, globular to egg shaped capsule, 4-7 mm long, hanging in clusters.
Seeds:
Black with a conspicuous whit spot on one end. Oblong 2-5 mm long.
Roots:
White or pale egg shaped bulb 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.
Key Characters:
Onion like smell when crushed.
Leaves all basal and strap like
Flowering stem sharply 3 angled, erect when in flower and collapsed by fruiting.
Less than 20 flowers per umbel and not globular
Flowers white and pendulous at anthesis.
Flower lobes or 'petals' with a green mid vein.
Perianth segments free or almost so.
Style distinctly divided into 3 near apex.
Anthers included in the perianth.
Filaments of all stamens lacking lateral appendages.
Seeds with elaiosome (oil gland).
After Harden and Macfarlane
Biology:
Life cycle:
Perennial. Seeds germinate in autumn and produce 2-4 leaves. The base of these leaves swell to produce the first year bulb in late winter to spring. The foliage dies off during summer. The bulbs emerge in autumn, produce leaves in winter and flower in spring to early summer producing seed. Bulb exhaustion usually occurs at early flowering. A new bulb is formed next to the parent bulb at flowering. The seeds mature over spring and the foliage again dies off over summer. Bulb exhaustion normally occurs at early flowering and this is often the best time for herbicide treatments.
Physiology:
Tolerates wind, part shade and seasonal waterlogging.
Reproduction:
By seeds and bulbs.
Flowering times:
August to November mainly in NSW and SA.
August to October in WA.
Mainly August to September in Perth.
Late winter to spring in SE Australia.
Seed Biology and Germination:
Produces large amounts of seed which is short lived and loses viability within a year.
Vegetative Propagules:
Round main bulbs, hemispherical daughter bulbs and small cormels
Hybrids:
Allelopathy:
Population Dynamics and Dispersal:
There are two methods of multiplication, by seed and by the production of bulbs. Both bulbs and seeds are spread by water, in produce and in soil adhering to animals and machinery. In urban areas it is often spread in top soil or during earthworks and in garden refuse.
Ants spread the seeds that have an oil gland (elaiosome) to attract them.
Often sold at fetes and markets.
It forms dense stands, leaving the soil bare over summer when the top growth dies which allows water movement to disperse the cormels and seed.
Origin and History:
Western Mediterranean, Southern Europe and Northern Africa.
Naturalised in SA by 1909.
Distribution:
ACT, NSW, QLD, SA, TAS, VIC, WA.
In the Avon wheatbelt, Jarrah forest, Swan coastal plain and Warren regions of the south west of WA.
Scattered throughout the populated areas of Tasmania, principally in towns and less frequently on roadsides.
Weed of Britain, New Zealand, USA.
Habitats:
Prefers full sun to part shade that is fairly sheltered, but will grow in open exposed conditions provided moisture is reliable.
Climate:
Warm temperate, Mediterranean.
Restricted to high rainfall areas.
Soil:
Sandy and heavier poorly drained soils. Granite outcrops.
A weed in pastures, orchards, dairy pastures, gardens, woodlands, sclerophyll forest, reserves, nature strips, streams, drains, wetlands, roadsides, orchards and damp, semi shaded coastal, riparian and windy areas.
Taints milk and meat products.
In domestic gardens and urban areas its smell is considered offensive.
Often forms pure swards in moist areas and excludes native vegetation.
Toxicity:
Not recorded as toxic.
Legislation:
Noxious weed of VIC, SA and TAS.
Secondary weed in Tasmania.
Management and Control:
Avoid moving soil from infested areas.
Autumn and spring cultivation helps kill bulbs but it takes several years for high levels of control.
Mowing and grazing provide control. Mow as low as possible just before flowering and repeat in a few weeks to control regrowth. Don't mow or slash infestations that have gone to seed. Heavy infestations are not readily grazed by stock.
Spray with 2,2-DPA or wipe leaves with glyphosate.
When applying foliar herbicides, use a wetting agent, especially on young plants as they are hard to wet.
2,2-DPA at 5 kg/ha plus 0.25% wetting agent applied before flowering provides good control in bushland.
Thresholds:
It is not a strong competitor but taints meat and milk even at low densities. About one days grazing on clean pastures is required to avoid the taint in milk.
Eradication strategies:
Manually remove isolated plants, bulbs and bulblets then burn to kill the bulb, bulblets and seed.
Annual spraying in late winter to early spring before full flowering, with 0.5 gram of metsulfuron(600g/kg) plus 25 mL Pulse Penetrant® in 10 litres of water, gives high levels of control. Best results usually coincide with applications at the bulb exhaustion stage which normally occurs at early flowering.
10 mL glyphosate per litre of water provides control but damages many companion plants.
Hormone herbicides applied just before flowering have given good control when combined with autumn cultivations.
2,2-DPA at 10 kg/ha plus 0.25% wetting agent applied before flowering provides high levels of control.
Management and Control:
Thresholds:
Eradication strategies:
Manually remove isolated plants and crush or burn the bulbs. Cultivate in summer to expose bulbs. Spraying in late winter to early spring, before flowering, with 0.5 g of metsulfuron(600g/kg) plus 25 mL Pulse® in 10 L water provides good control but will damage many broad-leaved species. Repeat for 2-3 years and replant 1 year later if necessary.
2,2-DPA, chlorsulfuron, and glyphosate should also provide control.
When applying foliar herbicides, use a wetting agent, especially on young plants as they are hard to wet.
Regular mowing provides control.
Herbicide resistance:
Biological Control:
Related plants:
Chinese Chives (Allium tuberosum)
Chives (Allium schoenoprasum)
Crow Garlic (Allium vineale) has leaves on its flowering stem and has multiple bulbs.
Allium roseum has up to 20 pink flowers and a cylindrical stem.
Plants of similar appearance:
False Onion Weed (Nothoscordum inodorum) has longer, cylindrical stems, many bulblets and does not have long pedicels supporting the flowers and does not have a strong onion like odour but its flowers are scented. It tends to flower later and is a weed.
Garland Lily (Calostemma purpureum). A native species of the eastern states.
Milkmaids (Burchardia umbellata) is a native species, has 1-2 leaves on the stem, a few, flat basal leaves and smaller more open flowers. It may be found from Two Peoples Bay westwards.
Ornamental Snowdrop (Leucojum vernum) has green spots on its petals and lacks the garlic smell when crushed.
Onion Weed (Asphodelus fistulosus) has no bulbs.
Purple Tassels or Vanilla Lily (Sowerbaea laxiflora) is a native species, has no bulb, fibrous roots, a few leaves on the stem and usually has purple to pink flowers (occasionally white) that are smaller and with 3 rather than 6 stamens. It may be found from Albany, Mt. Barker and the Kalgan River westwards.
Snowdrops (Leucojum aestivum) have green spots on white petals and no onion odour.
None of our common native species have a onion like odour.
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P17. Diagram.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P335. Diagram.
Blood, K. (2001). Environmental weeds: a field guide for SE Australia. (CH Jerram & Associates, Australia). P130-131. Photos.
Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume 4. P101. Diagram.
Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P16-17. Photo.
Hyde-Wyatt, B.H. and Morris, D.I. (1980). The Noxious and Secondary Weeds of Tasmania. (Tasmanian Department of Agriculture, Hobart, Tasmania). P99.
Paczkowska, G. and Chapman, A. (2000). The Western Australia flora: a descriptive catalogue. (Wildflower Society of Western Australia (Inc), the Western Australian Herbarium, CALM and the Botanic Gardens & Parks Authority). P29.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #53.15.
Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P783.
Moore, J.H. and Wheeler, J.R. (2008). Southern Weeds and their Control. (Second Edition). Department of Agriculture and Food Western Australia. P40. Photos.
Muyt, A. (2001). Bush Invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South East Australia. (R.G and F.J. Richardson, Australia). P 86-87. Photos.
Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P85-86.
Acknowledgments:
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.