Knobweed

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Hyptis capitata

Description

This is an erect, aromatic, robust perennial herb.

Stems it has several quadrangular branching stems that grow between 1 and 2.5 metres high.

Leaves are bright green with irregularly toothed edges. They are arranged opposite each other and are widely spaced on the stems. The leaves grow up to 12 centimetres long and 5 centimetres wide, tapering at both ends.

Flowers are small and white in compact globular heads about 1.5 centimetres wide on stalks to 5 centimetres long in leaf axils. It flowers during autumn.

Fruit is a four-lobed capsule dividing into 4 seed-like nutlets which, when ripe, rattle if the plant is shaken.

Habitat knobweed grows in disturbed areas in full sunlight on heavy soils. It retains above average moisture levels. It usually occurs on roadsides, creek banks, cultivated headlands and run-down pastures.

Weed characteristics invasive in a large number of environments.

Dispersal seeds are spread by water and by adhering to animals, people and vehicles.

Declaration Details

This species is not a declared plant under Queensland legislation but is considered a high priority in adjacent regions and its control is recommended.

How to act

Slashing and spraying of this weed are effective treatments. The spraying should be conducted at separate times but used in conjunction with slashing. Slashing on its own will not remove this weed. Correct grazing practices can also help to control this weed.

Refer to Weed Control Methods.

References

Related information

Knobweed © NQ Dry Tropics 2011
Knobweed © NQ Dry Tropics 2011

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