Trichomanes reniforme

Trichomanes reniforme is a fern distinctive for its undivided kidney shaped fronds which are its most recognisable feature and what give the plant its English common name, the kidney fern. The fronds, or laminae, are 3–10 cm by 4–13 cm and are a shiny, translucent green. The translucent nature of the kidney fern’s fronds is due to them being very thin, only one cell thick as a sporeling, which increases to 3-4 cells when the plant reaches maturity. The fronds are supported on brittle stipes 5–25 cm in length. Mature plants have a row of sori (a collection of sporangia) crowning the upper margin of their frond, where they resemble a row of small brown pegs. A unique feature of Trichomanes reniforme is its ability to curl up tightly during dry conditions in order to avoid moisture loss, an ability that gives rise to one of its Māori common names, kopakopa (to wrap or clasp). After rain or when conditions improve it unfurls and recovers completely.