Osmunda regalis
NPPA pest plant
Common names
royal fern
Family
Osmundaceae
Flora category
Vascular – Exotic
Structural class
Ferns
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
OSMREG
Conservation status
Not applicable
Simplified description
Tall deciduous fern, up to 2 m tall, occasionally with a trunk, fronds of two types, mostly large, up to 3 m long and 75 cm across divided into small flat leaflets up to 7 cm long by 1.8 cm across, with upper fronds sometimes made up of small rounded segments, like a bunch of grapes, turning from green to reddish brown in summer.
Distribution
Scattered from Northland to Wellington, locally abundant in Waikato.
Habitat
Fens often under open mānuka and grey willow (Salix cinerea), other wet peaty habitats including roadside drains, occasionally on exposed clay banks adjacent to water bodies.
Wetland plant indicator status rating
Information derived from the revised national wetland plant list prepared to assist councils in delineating and monitoring wetlands (Clarkson et al., 2021 Manaaki Whenua – Landcare Research Contract Report LC3975 for Hawke’s Bay Regional Council). The national plant list categorises plants by the extent to which they are found in wetlands and not ‘drylands’. The indicator status ratings are OBL (obligate wetland), FACW (facultative wetland), FAC (facultative), FACU (facultative upland), and UPL (obligate upland). If you have suggestions for the Wetland Indicator Status Rating, please contact: [Enable JavaScript to view protected content]
OBL: Obligate Wetland
Almost always is a hydrophyte, rarely in uplands (non-wetlands).
Detailed description
Rhizomes forming thick erect trunks to 150 cm tall. Fronds 30–300 × 20–75 cm, ovate, 2-pinnate, glabrous except when very young, dimorphic with the outer ones sterile and inner fertile. Fertile fronds bearing sterile pinnae at base and much reduced fertile pinnae at apex. Sterile secondary pinnae in up to 15 pairs, 2–7 × 0.8–1.8 cm, narrowly oblong, obtuse, ± truncate at base, often with a rounded lobe on one side. Fertile secondary pinnae to 3 × 0.4 cm, densely covered with clusters of sporangia.
Similar taxa
No other fern has the combination of deciduous dimorphic fronds.
Flowering
Late spring to autumn
Flower colours
No flowers
Fruiting
Late spring to autumn
Life cycle
Perennial. Wind dispersed spores.
Year naturalised
1890
Origin
Almost cosmopolitan apart from Australasia
Reason for introduction
Ornamental plant or as fibre-bearing plant for orchid cultivation.
Control techniques
Can be controlled manually, mechanically or herbicidally depending on situation.
Tolerances
Tolerates frost, wet, moderate shade, poor and acidic soils.
National Pest Plant Accord species
This plant is listed in the 2020 National Pest Plant Accord. The National Pest Plant Accord (NPPA) is an agreement to prevent the sale and/or distribution of specified pest plants where either formal or casual horticultural trade is the most significant way of spreading the plant in New Zealand. For up to date information and an electronic copy of the 2020 Pest Plant Accord manual (including plant information and images) visit the MPI website.
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA). Features description from Webb et al. (1988).
Some of this factsheet information is derived from Flora of New Zealand Online and is used under a Creative Commons Attribution 3.0 New Zealand licence.
References and further reading
Webb CJ, Sykes WR, Garnock-Jones PJ. 1988. Flora of New Zealand, Volume IV. Naturalised Pteridophytes, Gymnosperms, Dicotyledons. Botany Division, Department of Scientific and Industrial Research, Christchurch, NZ. 1365 p.
Popay I, Champion P, James T. 2010. An illustrated guide to common weeds of New Zealand, 3rd edition. NZ Plant Protection Society Inc, Christchurch, NZ. 416 p.