Redshank (Amaranthus)

Amaranthus cruentus L.

Family: Amaranthaceae.

Names:

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

Other Names:

Panicled Amaranth
Red Shank
Wild Amaranth

Summary:

An annual, erect herb with branched stems to 1.5 m high.

Description:

Cotyledons:

Two

Leaves:

Alternate.
Stipules - None.
Petiole - Yes
Blade - Dark green and often tinged with red. Oval. Pointed at tip. 30-100 mm long x 30-60 mm wide. Slightly wavy on the edges.

Stems:

Erect, branched, up to 1500 mm tall. Hairless or sparsely hairy near top. Dark green and often tinged or faintly striped with red. Succulent when young, becoming stiff then brittle with age.

Flower head:

In dense cylindrical spike that is terminal or in upper axils. Terminal spike may be up to 300 mm long.

Flowers:

No petals. Bisexual. Small.
Bracts - 1.5 times as long as perianth segments. Oval, membranous, with green midrib that passes into a relatively short tip.
Ovary - Superior. 1 celled.
Perianth - Papery, slightly prickly to touch due to points on elliptical perianth segments. Spreading below the ripe fruit.
Stamens -
Anthers -

Fruit:

A thin walled capsule containing numerous seeds. Somewhat wrinkled. Opening by a transverse line around the circumference near the middle.

Seeds:

Small. Brown. Shiny. Disk shaped. Enclosed by the persistent calyx.

Roots:

Often red or pinkish.

Key Characters:

Biology:

Life cycle:

Erect branched annual herb.

Physiology:

Reproduction:

Flowering times:

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Origin and History:

America. Asia.
Naturalised in Europe.

Distribution:

ACT, NSW, SA, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Disturbed ground and around yards and buildings.

Climate:

Soil:

Plant Associations:

Significance:

Beneficial:

Ornamental.

Detrimental:

Weed of vegetables and disturbed areas.

Toxicity:

May cause nitrate poisoning in sheep and cattle.

Symptoms:

Treatment:

Don't allow hungry or unaccustomed stock to graze Redshank.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

Boggabri weed (Amaranthus mitchellii)
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)
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:

Often confused with Slim Amaranth (Amaranthus hybridus) which has longer bracts giving the flower head a more spiky appearance.

References:

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). p158.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P66-67.

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). #68.3.

Acknowledgments:

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