Boggabri Weed

Amaranthus mitchellii Benth.

Synonyms - Euxolus mitchellii

Family: Amaranthaceae.

Names:

Amaranthus is from the Greek meaning "not to wither" and refers to the persistent flower spike.

Other Names:

Boggabri is often used in Queensland, but in other states this usually refers to Chenopodium carinatum. To reduce confusion it is suggested that Boggabri be used for C. carinatum and Boggabri weed for A. mitchellii.

Summary:

An almost hairless, annual herb with erect or ascending branches.

Description:

Cotyledons:

Two.

Leaves:

Alternate. Pale green.
Stipules -
Petiole - long.
Blade - Egg shaped, spear shaped or oblong. 20-63 mm long x 10-25 mm wide. Tapered to a slender petiole. Narrowed to a blunt tip.

Stems:

Erect or bending upwards. Up to 300 mm long. Pale green when young and turning yellow with age.

Flower head:

Dense, globular clusters in upper leaf axils or a short terminal spike with a few small leaves.

Flowers:

Whitish green. Small.
Bracts - Thin, chaffy, straw coloured when mature. Shorter than the female perianth.
Ovary -
Perianth - 2.5 mm long. 5 segments that are broadly spoon shaped with long narrow claws.
Stamens -
Anthers -

Fruit:

Membranous with a round ribbed basal portion containing the seed.
Seed just visible between the 5 perianth segments that have a short (1 mm) stalk and the broad, papery, finely pointed, outward bending laminas of the same length. Wrinkled and ribbed lengthwise with a thick smooth, conical top and three thick styles slightly exceeding the perianth segments. Does not split along a horizontal circular line.

Seeds:

Roots:

Taproot.

Key Characters:

Biology:

Life cycle:

Annual.

Physiology:

Reproduction:

Flowering times:

Most of the year. Mainly summer and autumn in western NSW.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Origin and History:

Australia.

Distribution:

ACT, NSW, NT, QLD, SA, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Bare ground and open grassland.

Climate:

Temperate, subtropical.

Soil:

Clay.

Plant Associations:

Grassland.

Significance:

Beneficial:

Fodder.

Detrimental:

Weed of pastures and disturbed areas.

Toxicity:

Contains potentially toxic levels of oxalates and nitrates.
Suspected to cause oxalate and nitrate poisoning in sheep. In Queensland hungry, transported, pregnant ewes died after exposure to Boggabri Weed.

Symptoms:

Death 3 weeks after exposure to the weed.

Treatment:

Don't expose unaccustomed stock to Boggabri Weed.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

Dwarf Amaranth (Amaranthus macrocarpus)
Foxtail (Amaranthus paniculatus)
Green Amaranth (Amaranthus viridis)
Love Lies Bleeding (Amaranthus caudatus)
Native Amaranth (Amaranthus interruptus)
Needleburr (Amaranthus spinosus)
Powell's Amaranth (Amaranthus powellii)
Redroot Amaranth (Amaranthus retroflexus)
Redshank (Amaranthus cruentus)
Rough fruited Amaranth (Amaranthus muricatus)
Slim Amaranth (Amaranthus hybridus)
Spreading Amaranth (Amaranthus deflexus)
South American Amaranth (Amaranthus quitensis)
Tumbleweed (Amaranthus albus) has tiny flowers in the leaf axils.
Amaranthus graecizans.
Batchelor's Buttons (Gomphrena spp.)
Cockscomb (Celosia spp.)

Plants of similar appearance:

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P330. Diagram.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P284.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P67-69. Diagram.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #68.9.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.