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Royal fern

Botanical Name Osmunda regalis
Family Osmundaceae
Origin Europe, West Asia, Africa, India, North and South America

Identification

Royal fern is a deciduous fern whose rhizomes form a short woody trunk, bearing large fronds of over 2m long and 750mm wide. The yellow-green fronds are feather-like, being subdivided twice. Fertile fronds are produced separately from the centre of the fern. The tips of these fronds form a mass of sporangia which is green, turning red, then rusty brown after the spores are released. From a distance, this looks like a flower spike, explaining it old name of ‘flowering fern’. Plants die back to the woody trunk in winter.

Habitats

Prefers acidic swampy soil and full sun to partial shade. Grows well under a light canopy of willows or manuka.

Impact to Biota and Ecosystems

Forms dense stands, excluding lower growing species and preventing native regeneration.

Dispersal Routes, Vectors, Infestation Sources

Wind born spores.

Management

Management 

Physical Control

Removing the top of the plant to below the white living stem tissue appears to be successful.

Disposal

Ensure all large cut portions of truck containing living stem tissue are not in contact with damp or boggy soils as they will re-grow.

Chemical Control

Glyphosate 100ml/10L water plus 20ml organo-silicone penetrant.

Asulam (Asulox) can be successful if applied in late November. Later spraying with Asulam when the fronds have hardened is not effective

Biological Control

Recommended Approach  

Further Comment

This plant is prohibited from propagation, sale and distribution within New Zealand!