Maidenhair Spleenwort

Description

Asplenium trichomanes, the maidenhair spleenwort, is a small fern in the spleenwort genus Asplenium. It is a widespread and common species, occurring almost worldwide in a variety of rocky habitats. It is a variable fern with several subspecies. The specific epithet trichomanes refers to a Greek word for fern. Asplenium trichomanes grows 10 to 30 cm tall forming tufts arising from a short, scaly rhizome. The scales are dark. The evergreen fronds are long and narrow, gradually tapering towards the tip. They are simply divided into small, yellow-green to dark-green, roundish pinnae. The stipe and rachis of the frond are dark all along their length. The fronds can reach 40 cm in length but are more commonly 8–20 cm. The indusia are linear to oval, straight, and attached to the upper-side of the fertile vein. There are (2) 4 to 8 sori per pinna and each are 1 to 3.5 mm long. Diploid (2n) chromosome count is 72. It is widespread in temperate and subarctic areas and also occurs in mountainous regions in the tropics. Its range includes most of Europe and much of Asia south to Turkey, Iran and the Himalayas with a population in Yemen. It occurs in northern, southern and parts of eastern Africa and also in eastern Indonesia, south-east Australia, Tasmania, New Zealand and Hawaii. It is found in North America and Central America and Cuba, and the northern and western regions of South America such as Chile. Even though its range is wide spread, it is often rare, and populations are widely spread out from each other based on the available of suitable habitat. It grows in rocky habitats such as cliffs, scree slopes, walls and mine waste, the type of rock used as a substrate depending on the subspecies. It grows from sea-level up to 3000 metres in North America while in the British Isles it reaches 870 metres. In the US state of Minnesota A. trichomanes is listed as a threatened species. It occurs on ledges and in crevices on moist, east-facing cliffs and occasionally on talus with similar conditions. The Minnesota populations are Asplenium trichomanes subsp. trichomanes.