Also known as
Monkey flower, Mimulus guttatus
What does it look like?
Erect perennial bog herb (<60 cm tall) with rhizome root system, stiff, thick and occasionally branched stems. Oval bright green leaves (<12 x 8 cm) are usually hairless with serrated edges. Yellow flowers (3cm diameter) with red spots on the bearded lower lip appear from Nov-March, followed by 2-valved seed capsule (1 cm long) containing many patterned seeds.
Are there any similar species?
Mimulus moschatus is smaller, sticky-hairy perennial, flowers (2cm diameter) with no red blotches, common. M. luteus is similar, in cultivation.
Why is it weedy?
Tolerant of cold to hot, wind, semi-shade, most soils. Fast growing, has creeping rhizomes root system, and seeds and fragments of root system are widely dispersed.
How does it spread?
Seeds and fragments of rhizome roots in water, dumped soil, vegetation, and drain and pond contents.
What damage does it do?
Invades freshwater margins, replacing native species.
Which habitats is it likely to invade?
Swamps, lakes, streams, wet places throughout NZ.
What can I do to get rid of it?
1. Dig out small patches (all year round): dispose of at refuse transfer station, burn or bury.
2. Overall spray (all year round): glyphosate (100ml/10L + penetrant).
What can I do to stop it coming back?
Plant tall species to create shade. Begin control at top of catchment.