NCSO invasive plants Aquatic Species Questions with 100% Correct Answers

Alligator weed (Alternanthera philoxeroides) Correct Answer Scientific name: Alternanthera philoxeroides (Mart.) Griseb. (ITIS) Synonym: Achyranthes philoxeroides (ITIS) Common names: Alligatorweed, alligator weed, pig weed Native To: South America (Spencer and Coulson 1976) Date of U.S. Introduction: First reported in Alabama in 1897 (Masterson 2007) Means of Introduction: Probablyintroduced through ballast water (Masterson 2007) Impact: Forms dense mats that crowd out native species and impede recreational activities such as boating, swimming, and fishing (Texas Invasives 2007) Current U.S. Distribution: Southeastern U.S., California Brazilian Waterweed (Egeria densa) Correct Answer Threats to Native Habitats Brazilian waterweed forms dense monotypic stands that crowd out native aquatic plants and degrade wildlife habitat. The dense growth that is typical of this plant can limit surface water use for activities such as fishing, swimming and boating. It can also cause increased sedimentation and can affect water quality. Its dense growth retards water flow, which may interfere with irrigation projects and hydroelectric utilities. It easily spreads by fragments and can colonize large areas in a relatively short period of time. Because it is a popular aquarium plant, this ability to invade new areas via the dispersal of stem fragments makes the dumping of aquariums into aquatic natural areas a particular concern. It is a considered a noxious weed in some states. Description Brazilian waterweed is a submerged aquatic perennial plant with a trailing growth habit. At first glance it looks like an enlarged version of our native waterweeds (Elodea canadensis and E. nuttallii). The basic structure of the plant is a stem with whorls of four to six small leaves. Leaves vary from one-half to one-and-a half inches in length and are sessile (lacking a stem). Brazilian waterweed leaves are noticeably longer and wider than our native waterweeds. Unlike our native waterweeds, which have a smooth leaf margin, Brazilian waterweed has tiny fine teeth along its leaf margins. Plants produce three-quarter-inch wide white flowers that are elevated about an inch above the water. All North American populations of Brazilian waterweed reproduce vegetatively as no seeds and/or female flowers have ever been observed on populations found here. Vegetative reproduction is achieved by lateral buds arising from numerous specialized nodal regions on the stems. Only fragments containing specialized nodes can develop into new plants. Curly Pondweed (Potamogenton crispus) Correct Answer Scientific name: Potamogeton crispus L. (ITIS) Common names: Curly pondweed, Curly-leaf pondweed Native To: Eurasia, Africa, Australia (Catling and Dobson 1985) Date of U.S. Introduction: Mid-1800s (Catling and Dobson 1985)