Woodsia ilvensis, commonly known as Oblong Woodsia, is a fern found in North America and northern Eurasia. Also known as Rusty Woodsia or Rusty Cliff Fern, it is typically found on sunny, exposed cliffs and rocky slopes and on thin, dry, acidic soils.
Its distribution is circumpolar and is most abundant in Scandinavia
, the Ural
mountains and the eastern United States
. It is also found in Japan
, coastal Greenland
and various European locations including the Alps
It is considered "Threatened" or "Endangered" in the states of Illinois, Iowa, and Maryland and "Presumed Extirpated" in Ohio. Also found in West Virginia and North Carolina, it is the most common Woodsia species in the US.
Its UK distribution is confined to Angus and the Moffatt Hills in Scotland, north Wales and Teesdale and the Lake District in England. There are fewer than 90 wild clumps in the whole of the UK, where is on the edge of its natural range and is considered to be "Endangered".
Discovery and identification
The plant was first identified as a separate species from specimens collected in Scotland in James Bolton's 1785 publication Filices Brittanica
. Bolton distinguished between Acrostichum ilvense
and Acrostichum alpina
, now Woodsia ilvensis
and Woodsia alpina
respectively, which had previously been conflated. The genus Woodsia
was established in 1810 by Robert Brown
, who named it named after the English botanist Joseph Woods
" is the Latin
name for the island of Elba
The leaves are typically 6 inches long and 1 inch wide, with stiff, erected pointed tips and cut into 12 nearly opposite stemless leaflets. The underside of the leaves are covered in white woolly fibres, which later turn rusty brown.
Victorian collectors and modern conservation
Oblong Woodsia came under severe threat from Victorian
fern collectors in the mid 19th century in Scotland, especially in the Moffat
Hills. These hills once had the most extensive UK populations of the species but there now remain only a few small colonies whose future is under threat. This period of collecting became known as Pteridomania
(or "fern-fever"). The Royal Botanic Garden Edinburgh
plan to use cultivated specimens and a spore bank to restore depleted wild populations.