Growth Habit: The soft and feathery-looking, aromatic leaves are initially crowded into a loose basal rosette and are alternately arranged along the upright stems. Numerous short-lived upright (i.e. erect or ascending) stems usually growing 10-60 cm tall, but occasionally reaching up to 1 m in height, are produced each year. It has an extensive network of creeping underground stems.
Type of Plant: Yarrow is an erect mat-forming, perennial herb.
Flowers: Five (occasionally 4-7) petalled white or pale pink flowers, 5-7 mm across. The plant has many flowers that are located in attractive tight flat topped or slightly rounded clumps mainly at the top of the plant. The flower clusters are can be up to 15 cm across, but usually 4-10 cm. Yarrow flowers in summer and autumn.
Fruit/Seed: A single plant can produce large quantities of seeds due to the abundant flowers.
Dispersal: Yarrow reproduces by seed and by its underground stems.
Distribution: Yarrow is a common plant in English cottage-style gardens. It has however escaped gardens and now forms significant weedy infestations on roadsides, turf, pasture areas, neglected gardens and wastelands. Yarrow forms significant weedy infestations in Tasmania, but here it is generally seen as a weed of roadsides, turf and pasture areas. It is relatively widespread and common, particularly in agricultural areas the north-east (e.g. in the Tamar Valley) and in settled areas around Hobart in the south-east (e.g. in the bushland areas fringing the Derwent River). However, it is a potential weed of some significant sub-alpine and alpine areas in the western parts of Tasmania.
Status: Undeclared in Tasmania, but has the potential to be a significant environmental weed.
- Yarrow can cause skin irritation if juice is left on the skin and then exposed to the sun.
- Once established in grassed areas, such as home lawns or pasture, it can be difficult to eradicate.
- Is a significant environmental weed in alpine areas in southern Australia, so could be an issue in Tasmania.
- Spreading underground stems can make Yarrow very difficult to remove from gardens and lawns.
- Dairy cattle which eat it are also reported to produce tainted milk.
- Yarrow has also been used medicinally due to it containing ethereal oils and small quantities of furocoumarin.
For further information contact the Department of Primary Industry, Parks, Water and Environment, Tasmania.
- Grubbing (spring and summer). The flower heads should be removed before seeding and destroyed. Manual removal of the plant is effective as long as its creeping root system is also removed. Dispose of the material carefully, as the root system can regrow.
- Herbicide. Spot spray. Herbicides registered in Tasmania include MCPA and glyphosate.
N.B. Always check the herbicide label before use.