Pteris ensiformis
Common name
slender bracken
Family
Pteridaceae
Flora category
Vascular – Exotic
Structural class
Ferns
Conservation status
Not applicable
Distribution
Exotic. New Zealand: North Island (sparingly naturalised in Auckland and Hamilton). Widespread throughout the tropics—apparently only indigenous to India, Sri Lanka, Australia (north-eastern Queensland), South East Asia and Polynesia (as far east as Samoa).
Habitat
Stone, brick and block retaining walls and wasteland in urban areas
Detailed description
Short slender (gracile) terrestrial and/or lithophytic ferns. Rhizome short creeping to suberect, scaly; scales narrowly triangular, brown. Fronds ± dimorphic. Stipe to 200 mm long, pale green; base scaly. Lamina 1-pinnate, with pinnae (apart from apical pinna) increasing in length from apex to base. Sterile lamina c. 200 mm long; lower pinnae pinnate to pinnatifid, to 160 mm long; ultimate segments c. 8–10 mm wide, oblong to ovate, irregularly serrate. Fertile lamina to 300 mm long, narrower than sterile; pinnae forked near their base; ultimate segments linear to narrowly oblong, serrate only at their apices. Veins free, oblique, 1–2-forked. Sori continuous from near base to near apices of fertile pinnae or pinnules; paraphyses scarce.
Similar taxa
Distinguished from the other indigenous and naturalised species of Pteris in New Zealand by the smaller stature, strongly dimorphic, variegated, 1-pinnate (lowermost pinnae 1-pinnate-pinnatifid) oblong to ovate fronds up to 500 mm long, with free veins and stalked undivided pinnae and pinnae segments (sometimes more broadly attached but never decurrent on rachis or costae). Pteris ensiformis is, in New Zealand anyway, a rather delicate little fern.
Propagation technique
Easily grown from spores and inclined to be weedy but cold sensitive which appears to restrict its ability to spread.
Year naturalised
2009
Origin
Presumably naturalised via the horticultural trade as this species was once a popular pot plant sold widely throughout New Zealand during the 1970s.
Control techniques
Not very invasive although it can be weedy in suitable habitats. Being cold sensitive it is virtually confined to crevices in stone, brick and concrete block walls where it can be a minor problem.
Etymology
pteris: A fern known to the ancient Greeks; from the Greek pteris
Notes
New Zealand collections are all represented by a variegated form (P. ensiformis cv. Victoriae) which was widely sold in nurseries during the 1970s. In this form the inner portions of the pinnae are coloured milky white to yellow and the outer dark green to yellow-green.
Attribution
Fact Sheet Prepared for NZPCN by: P.J. de Lange (18 January 2012). Description adapted from Kramer & McCarthy (1998).
References and further reading
Kramer KU, McCarthy PM. 1998. Pteridaceae. Flora of Australia 48, Ferns Gymnosperms and allied groups: 241–248. ABRS/CSIRO Victoria, Australia.