Species Overview

Native to: Caribbean, Central and South America

Wright’s nutrush is a non-native sedge that has been increasing in Florida wetlands. It was first recorded for Florida in 1988 in Jane Green Swamp, an herbaceous marsh in the Upper St. Johns River Basin. Introduced populations remained small and localized in Florida until 2001 when hundreds of acres were reported in the Blue Cypress Water Management and Conservation Areas in the Upper Basin of the St. Johns River. During 1999-2002, a period of extended drought, populations expanded dramatically in marshes of the Upper Kissimmee Basin, into wetlands of the Okaloacoochee Slough, and in natural areas in Lee County.

Species Characteristics

Family: Cyperaceae

Habit: Sedge, individual plants typically have one to five lead stems that grow from 75 to 200 cm (29 to 79 in) tall. Stems are strongly three-sided and heftier in girth than other grass-like species occurring in Florida marshes. Each angled side measures 1.5 to 2.5 cm (0.59 to 1 in) across. Vertical streaks of dark red run down the stem base and through the roots.

Leaves: grow up to 60 cm (24 in) long and 2.5 cm (1 in) wide. Linear in shape, they taper broadly to end in a blunt tip, known for their "W-like" pleat and reflective shine. Younger plants hold their leaves tightly upright; but as they grow, the stems elongate, making the leaves droop and become widely spaced. At maturity, plants appear lanky with rarely more than 6 to 8 leaves developing off a single stem.

Flowers: produced on rigid stalks that emerge from the top of stems. These stalks can grow to 30 cm (11.8 in) before they mature.

Seeds: achenes/nutlets are oval to elliptic and softly triangular in outline, especially at the base. At 3.5 mm (1.4 in) long, they are larger than the seeds of native nutrush species. A shining jade-green when fresh, seeds turn mottled tones of olive-grey to white when dry.

Distribution in Florida: South and Central

Impacts

Spreads via abundant and highly viable wind dispersed seeds. It alters the composition and structure of native wetland communities. For many years, Wright's nutrush may be the dominant species and grow to suppress the local plant community; in other years, it may be completely absent. Such sporadic appearances are a direct result of surface water in the environment. Seedling emergence is restricted by continually saturated or flooded substrates. Constant habitats in general, whether wet or terrestrial, are not suitable for Wright's nutrush. Seasonal wetlands however are highly susceptible to invasion.

Thoroughly clean boats, equipment, and gear before leaving infested areas. Seed is primarily transported by airboats. Airboats moving across wetland vegetation will shatter seed heads and become effectively contaminated in the process. A shop vacuum lined with a heavy paper bag is recommended to clean out boats.

Individual plants do not spread or produce runners and are easily pulled from the substrate. Pulling up seedlings and clipping the seed heads is feasible in small, localized populations if return visits are made. Seed heads clipped from mature plants should be dropped directly into heavy bags, sealed, and land-filled. Gloves, long sleeves, and long pants should be worn to protect from the prickles. In areas where water management is possible, a delay in the implementation of draw down in spring will result in a similar delay of seedling emergence. Because plants that emerge weeks to months later than normal have been shown to lag significantly behind in size and in ultimate seed production, draw down delays may be useful as part of a long-term management program.

None known.

Application of a 0.05% solution of herbicide product that contains 2 lb a.i. diquat dibromide (with surfactant) to small seedlings, which should be present in June, can destroy 100% of the plants. Later application in mid-July, when plants are more developed, will require solutions of 0.1% to 0.2%. Due to the dense, over-lapping growth at the later growth stage, a follow-up herbicide treatment should be completed within 14 days of the initial application to ensure that all plants within the treatment area are treated. It is important to consult an expert for assistance in developing the most effective and integrated approach to management.