Raphanus raphanistrum subsp. maritimus Sea Radish

A coarse, bushy biennial or perennial herb of coastal habitats such as sand dunes, shingle and waste places near the sea. It is bigger than Wild Radish (Raphanus raphanistrum ssp. raphanistrum) with brighter yellow flowers which give rise to larger, beaded fruit capsules. The fruits, which accumulate at the base of the plants at the end of summer, are somewhat corky at maturity and will float in seawater. In autumn they are swept out on the high tides and this allows them to be dispersed around the coast. As a result, its large, leafy rosettes are frequently found growing near the high spring tide line in the strand line or in foredunes. It  is a Mediterranean-Atlantic species which has a maritime distribution in Britain, mostly found along the west coast and it is a common coastal plant in Wales. It has become more common in Glamorgan in the last 50 years where it is now a frequent member of the local sand dune flora. 

Native

Notes: The Sandhill or White Snail (Theba pisana) is a native of the Mediterranean region and was introduced to Britain in the 1700s (see photo). It is largely restricted to frost-free coastal areas in the south-west of the UK, where it is an important herbivore, occasionally attaining very high densities. In some years feeding damage can result in almost complete defoliation of species such as Sea Radish in parts of Swansea Bay.