Salvinia molesta D.S. Mitchell was discovered growing on OÎahu in Enchanted Lake, Kailua and in Lake Wilson, Wahiawa, in April 1999. The first collection was made on 14 April 1999 at Kailua off Kiukee Place, Kaelepulu Pond, Enchanted Lakes by L. Nakahara, R. Heu & N. Matayoshi (#99-01, BISH). On 15 April 1999 the Honolulu Star-Bulletin reported on planned eradication effors of this noxious, aquatic weedy fern. Salvinia molesta is a free floating fern that is sexually sterile but reproduces by fragmentation and is capable of doubling in volume in 2 to 3 days to form extensive floating mats. The dense mats of S. molesta clog waterways and irrigation canals, block passage, obstruct irrigation pumps, prevent light from reaching aquatic plants, reduce the oxygen content of the water and seriously degrade the quality of the water.
The leaf surface is covered with minute stalks bearing 3 or 4 hairs joined at the tips forming cage-like structures that resemble inverted kitchen whisks. This fern is grown in garden ponds and aquaria and is known to be in cultivation in the Islands. It escapes from cultivation and invades aquatic fresh water bodies where is grows aggressively, rapidly becoming a serious pest. It is listed on the Federal Noxious Weed list. Every effort needs to be made to control the growth and spread of Salvinia molesta.For information about S. molesta in the United States and for general information about the plant, visit the Nonidigenous Aquatic Fern Information page of the Nonindigenous Aquatic Species (NAS) information resource of the United States Geological Survey (USGS) .
