New record of Eichhornia crassipes (Water Hyacinth) from north of Iran

In October 2012, in a survey in order to study the flora of paddy fields and aquatic ecosystems of Gilan province (N Iran), we encountered an unknown species in “Aynak lagoon” in southeast of Rasht, covered surface of about 12 ha pond densely. Comparing the flora of pond with previous years or adjacent ponds showed that, the new weed was dominant in interference with natural flora of aquatic ecosystems in the area and almost all indigenous flora of this pond were disappeared by the introduction of new weed. Studying weed morphology using scientific resources indicated that new plant was Eichhornia crassipes (Mart.) Solms. belonging to Pontederiaceae family (Holm et al. 1977) with common name Water Hyacinth. Some features makes it unique and easy to identify E. crassipes including: glossy green oval-shaped leaves have a waxy round 10–20 cm across, 50 to more than 100 cm height, floating above the water surface, bulbous spongy and inflated stalks, the feathery freely hanging roots and purple-black, erect stalk supports a single spike of 8–15 conspicuously attractive flowers, mostly lavender to pink in color with six petals. Water Hyacinth panicle is up to 30 cm long. The flowers have six stamens and fruit capsule containing the seeds are chambered (Langeland & Burks 1998).