Wingletang Down is a Site of Special Scientific Interest (SSSI) on the southern side of the island of St Agnes in the Isles of Scilly, England, UK, which is noted for its biological characteristics. The site is managed by the Isles of Scilly Wildlife Trust and is within the Isles of Scilly Heritage Coast and the Isles of Scilly Area of Outstanding Natural Beauty. It is the only site in Great Britain and Ireland for the small fern, least adder's–tongue (Ophioglossum lusitanicum). As of 11 September 2009 the SSSI was considered to be in ″unconditional recovering″ condition because European gorse (Ulex europaeus) and bramble (Rubus fruticosus) are at unacceptable levels.