Least adder's-tongue

Appearance

''Ophioglossum lusitanicum'' is a small winter annual fern, and consists of a simple sterile blade attached to a spike-like fertile blade with between three and eight sunken sporangia on either side. The whole plant rarely exceeds a height of 2 cm.

This species has a chromosome number of 2''n'' = 250–260.

Distribution

''Ophioglossum lusitanicum'' is native to: Africa and India. It is also found on the western seaboard of Europe ; the Atlantic Islands ; the Middle East ;) South America ; and Australasia .

The distribution in Britain is restricted to one small area of coastal heath on St Agnes, Isles of Scilly where it was discovered by John Raven in 1950. It grows in short turf on Wingletang Down where some of the colonies are suffering from an increase of competitive grasses, gorse and bramble . ''Ophioglossum lusitanicum'' is listed on Schedule 8 of the Wildlife and Countryside Act 1981, and is within a Site of Special Scientific Interest .

In Australasia and South America, this species is represented by a subspecies, ''Ophioglossum lusitanicum'' subsp. ''coriaceum'' R.T. Clausen

Habitat

As this species is a winter annual, it requires a warm winter environment. In its British populations, it favours thin, unshaded, peaty soils in south-facing localities.

''Ophioglossum lusitanicum'' subsp. ''coriaceum'' has a much broader ecological range in southern Australia, where habitats include damp open sites; from coast meadows to alpine grassland. It is found in New South Wales, Tasmania, Queensland, and other states.