About Sticherus cunninghamii (Heward ex Hook.) Ching
Sticherus cunninghamii, commonly called umbrella fern, is a fern species endemic to New Zealand. The species is named for Allan Cunningham, an English botanist and explorer. Its Māori names are rarauheriki, waekura, and tapuwae-kōtuku. This fern is characterized by drooping fronds that take an umbrella-like shape, which distinguishes it from its relative S. flabellatus that has fan-shaped fronds. The angle between the first branches on a frond is narrow, measuring approximately 44°. Fronds are 15 to 30 cm long, with an erect stipe that is typically 20 to 50 cm high, and may occasionally reach 1 m in height. The final, longest leaf segment on the frond grows up to 18 mm long, and unlike the equivalent segment on S. flabellatus, it is not serrated. Leaves are split into two halves that fan out, with a dormant bud located between the halves. This dormant bud sometimes grows into additional pinnae, a pattern seen most often in plants that grow along the ground rather than on banks. The underside of leaf segments is white or glaucous, and covered with broad scales that are brown at the center and fade to a pale color at the margins. Sori are arranged in one row on each side of the midrib; each sorus contains around five sporangia, and spores measure 29–31 μm by 14–15 μm. This fern grows in patches from a long, much-branched creeping rhizome covered in dark brown scales. Its fronds characteristically grow into two or three separate tiers of umbrella-shaped structures. S. cunninghamii is endemic to New Zealand; it is common across the North Island, especially in the central volcanic area, and is rarer in the eastern and southern parts of the South Island, as well as on Stewart Island and the Auckland Islands. It grows from lowland to montane forest, most often along shaded stream banks and road cuttings, where it can become the dominant ground cover. It is used in traditional Māori rongoā herbal medicine. One specimen collected in 1888 for King Tāwhiao is annotated that the sap of this fern is a powerful narcotic. This plant is very difficult to transplant and cultivate.
