Scentless Mayweed
Matricaria perforata
Washington State Classification
Class C — Widespread, County-Selected Control
It is able to invade cultivated fields and prevent the harvest of small grains.
Quick Reference
Identification
Growth Habit
Scentless mayweed is an annual to short-lived perennial with upright stems reaching 6 inches to 3.25 feet tall. Its leaves are dissected with narrow segments and daisy-like flowers bloom generally summer through early fall.
Leaves
Leaves are alternately arranged and dissected into narrow, thread-like segments. They are essentially odorless when crushed.
Flowers
Flowerheads are solitary at stem ends, have overlapping rows of bracts at their base and have two types of flowers: ray flowers which are white and look like a daisy petal and disk flowers which are yellow and compact, forming the ‘daisy center’.
Fruit & Seeds
Seeds are dark brown and have 3 ridges on one side.
Impact
It is able to invade cultivated fields and prevent the harvest of small grains. Its spread can go unnoticed due to its similarity to Anthemis arvensis (corn chamomile, dog fennel or mayweed) another common weed. It may also spread as a seed contaminant.
Ecology & Spread
Habitat
It grows along roadsides, fence lines, waste areas, in perennial forage crops, cultivated fields and particularly on heavy soils. Please click here to see a county level distribution map of scentless mayweed in Washington.
Spread Mechanisms
Reproduction
Scentless mayweed reproduces by seed. Each plant can produce up to 300,000 seeds.
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Control Methods
Mechanical
- Plants may be mowed to slow flower production, but plants may still grow and form more flowers below the cut height. Small infestations can be hand pulled.