First records of Barringtonia asiatica (Lecythidaceae) from UK waters and a review of north-western European records

Abstract

The tree that produces the Box Fruit is known as the Fish Poison or Sea Poison Tree, Barringtonia asiatica (L.) Kurz, which is native to mangrove habitats on tropical coasts and islands in the Indian and western Pacific Oceans from Zanzibar east to Taiwan, Philippines, Fiji, New Caledonia, Solomon Islands, Cook Islands, Wallis and Futuna Islands, and French Polynesia. B. asiatica was one of the first successful colonists of Krakatau Island (Indonesia) after most of its vegetation was destroyed by volcanic eruptions during 1883. Although the species is not native to the western tropical Atlantic, it has been widely planted in this region and elsewhere and now has a pantropical distribution. It is a bushy tree that grows up to 20 m in height and has spoon-shaped leaves with prominent veins. The tree produces spectacular flowers which only open for one night; the 4–5 white petals and pink stamens fall away by dawn. When intact, the outside casing (exocarp) of the Box Fruit is thin and papery, while the underlying mesocarp is thick and fibrous. Each fruit contains a solitary seed in the centre. Due to their high-level of buoyancy, Box Fruits have been used by traditional fishermen as floats for their nets. The seed, measuring 40–50 mm in diameter, contains a saponin toxin which is used to make fish poison (Gunn & Dennis, 1976; Nelson, 2000; Perry & Dennis, 2010). On 21 January 2012, PAG found a specimen of the Box Fruit stranded on Crantock Beach (50.407232uN, 5.118219uW), near Newquay, Cornwall. The well-worn specimen, which measured c. 75 mm at its base, was virtually devoid of its exocarp, but exhibited fully its very fibrous interior (mesocarp) (Fig. 1). There were no overt signs of any colonising macro-epibionts on the surface of the specimen. This specimen represents the first known record of B. asiatica from UK waters. On the 16 February 2014, and following a prolonged period of severe storms during the first half of February, AD found a specimen of the Box Fruit stranded on the wrack line of the highest storm ridge between Camber Sands and Dungeness on the East Sussex and Kent border (50.923839uN, 0.85432708uE). The square-shaped dark-brown smooth outer exocarp, measuring c. 90 mm in height, c. 90 mm in width, and c. 110 mm from corner to corner at its base, was extensively eroded, exposing the underlying straw coloured fibrous mesocarp (Fig. 2). There were no overt signs of any colonising macro-epibionts on the surface of the specimen. This specimen represents the second known record of B. asiatica from UK waters. There are only two previous records of B. asiatica from European waters. The first specimen, which was extensively eroded, was found stranded during January 1985 on Inishskea Island, Co. Mayo, western Ireland (Viney, 1985, 2000). Nelson (2000) was convinced that the latter specimen was a genuine peregrine drifter. On 12 January 2012, the second specimen, which was reported to have been very fresh, was found stranded on the Dutch North Sea *Corresponding author: declanquigley@eircom.net Figure 1 Box Fruit, Barringtonia asiatica, found stranded on Crantock Beach, near Newquay, Cornwall, on 21 January 2012 (Paul Gainey).