Chenopodium is from the Neo Latin form of the Greek words Khenopous from khen, a goose, and pous, a foot and refers to the shape of the leaves in some species.
The mature plant is an annual and very variable in size and form. Usually it is an erect, annual, bushy herb with no aroma, reaching a height of 1.0 m or more. It usually has striped stems. The leaves are elliptic to diamond-shaped, 20-60 mm long and 5-30 mm wide with a pointed tip, the lower leaves sometimes have angular teeth. The upper surface of leaf is green and the lower surface mealy white. It has dense clusters of tiny green flowers which are each 1.5-2.5 mm across and have 5 floral segments and 5 stamens. The tiny fruits are held horizontal in the floral segments.
Native to Europe, Fat Hen is a weed of horticulture and often found on waste land. It flowers in spring and autumn.
Two. Long and narrow, 13-18 mm long with a distinctive grey/green colour. Tip round. Base tapered. Hairless. Petiole is 3 to 5 mm long. The seedling has a hypocotyl and epicotyl.
The first leaves are 15 to 20 mm long, diamond shaped, with a petiole approximately 5 mm long, and frequently mealy. Acute tip. The leaves in the seedling and young plant are paired, the pairs being at right angles to each other.
Alternate, succulent but thin. Variable colour, size and shape. In the mature plant they tend to grow singly. Later leaves develop a lobed margin. The plant does not form a rosette.
Petiole - Long.
Blade - Variable. Egg, wedge or oval shaped, 12-60 mm long by 8-35 mm wide, hairless. Coarsely toothed edges. Usually with mealy scales that colour it grey green to bluish, especially the lower leaf surface which may be whitish. The under surface is usually paler than the upper surface. Acute tip.
Stem leaves - Usually not toothed and lance shaped, up to 60 mm long with a 40 mm petiole. The leaves are hairless and mealy grey/green in colour. Acute tip. Upper leaves have almost no petiole.
The stems branch from the base and along their length, are polygonal in cross section, stout, solid, hairless, and with dark lengthwise stripes. Branches are often reddish or with red stripes. They may be slightly mealy. 200-2000 mm tall. Typically bushy and mealy with many branches but may be single stemmed.
Leafy cluster of tiny flowers extending beyond the leaves, terminal on the stem and branches and appear to be in the leaf axils. Long narrow or loose panicle.
About 2 mm in diameter, mealy, green to greyish, and five lobed. Hermaphrodite. Sessile (no stalk). The end flowers are the largest.
Ovary - Smooth, hairless.
Perianth - 5 lobes. Tube similar in length to the lobes. Lobes are egg shaped, membranous on the edges, somewhat keeled and have an obtuse tip.
Stamens - 5
Membranous, smooth, hairless pericarp surrounds the seed and may be easily removed.
Shiny, black, smooth, bluntly keeled, horizontal, flattened, circular in outline.
Stout taproot with many laterals.
5 perianth lobes. Mealy leaves and flower heads. Toothed leaves. No significant smell when crushed. Seed horizontal. Erect habit.
Annual. Germination occurs from spring to autumn depending on soil moisture. It grows rapidly through summer and autumn especially in irrigated crops or moist areas. It then dies quickly after maturity. Very small plants may flower.
November to August in SA.
Summer to autumn in NSW.
March to April and October to December in Perth.
Seed Biology and Germination:
Forms hybrids with closely related species giving a multitude of forms.
Population Dynamics and Dispersal:
Origin and History:
Cosmopolitan or European and Asia.
ACT, NSW, NT, QLD, SA, TAS, VIC, WA.
Occurs in all parts of Tasmania.
Prefers eutrophic conditions.
Wide range. Prefers areas rich in nitrogen.
Relatively palatable fodder.
Vegetable, young leaves eaten raw or boiled in prehistoric times and during the famine of World War 2 in Europe.
Flour from the seeds was used for baking.
It is a major weed in cereals and arable crops and can offer serious competition during the establishment stages of pasture and legume crops.
Hormone herbicides provide good control and Spray Grazing with 1 L/ha 2,4-D amine is cheap and effective.
Hand pull plants after elongation and before seeding in summer. Fat Hen is relatively tolerant to normal rates of glyphosate. For small areas use 2 L/ha Spray.Seed® plus 2 kg/ha simazine(900g/kg) plus 1% spray oil in early summer for control of existing plants and residual control of seedlings for the season. Wear protective clothing if hand spraying this mix.
In bushland areas, use 4 L/ha 2,4-DB(400g/L) or 80 mL 2,4-DB plus 25 mL wetting agent in 10 litres of water in early summer on young actively growing plants for reasonably selective control. In areas where hormone herbicides are restricted, use 25 g/ha Broadstrike® plus 0.5% Uptake® or 0.5 g Broadstrike® plus 50 mL Uptake® in 10 L water on young plants. A repeat application may be required in years where summer rains induce late germinations.
Grazing or mowing normally provides control.
Fat Hen often flourishes in areas that have recently been fenced off.
Small leaved Goosefoot (C. desertorum ssp. microphyllum)
Stinking Goosefoot (C. vulvaria)
Wormseed (C. ambrosioides var. anthelminticum)
(C. polygonoides) Einadia polygonoides
(C. pseudomicrophyllum) C. desertorum ssp. microphyllum
(C. rhadinostachyum) Dysphania rhadinostachya
(C. trigonon) Einadia trigonos
Plants of similar appearance:
Fat Hen is distinguished from Nettle-leaved Goosefoot by its lighter colour and by the leaves which are longer, narrower, and usually less lobed.
Fat Hen differs from Small Crumbweed (Dysphania rhadinostachya) in its erect habit and its larger more angular leaves with minute mealy-white hairs.
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