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   Andropogon virginicus (sedge)     
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      Andropogon virginicus (Photo: Clifford W. Smith, University of Hawaii Botany Department, - Click for full size   Andropogon virginicus (Photo: Clifford W. Smith, University of Hawaii Botany Department, - Click for full size   Andropogon virginicus (Photo: Clifford W. Smith, University of Hawaii Botany Department, - Click for full size
    Taxonomic name: Andropogon virginicus L.
    Synonyms: Anatherum virginicum (L.) Spreng., Anatherum virginicum (L.) Spreng. subvar. tetrastachyum (Elliott) Roberty, Andropogon curtisianus Steud., Andropogon dissitiflorus Michx., Andropogon eriophorus Scheele, Andropogon tetrastachyus Elliott, Andropogon vaginatus Elliott, Andropogon virginicus L. subsp. genuinus Hack., Andropogon virginicus L. subvar. genuinus Hack., Andropogon virginicus L. subvar. typicus Hack., Andropogon virginicus L. var. genuinus Fernald & Griscom, Andropogon virginicus L. var. tetrastachyus (Elliott) Hack., Andropogon virginicus L. var. vaginatus (Elliott) A.W.Wood, Andropogon virginicus L. var. viridis Hack., Cinna lateralis Walter, Sorghum virginicum (L.) Kuntze
    Common names: broomsedge (English), broomsedge bluestem (English), whisky grass (English), yellow bluestem (English), yellowsedge bluestem (English)
    Organism type: sedge
    The perennial bunchgrass (Andropogon virginicus) commonly known as broomsedge sometimes forms continuous cover in boggy, open mesic or dry habitats. It releases highly persistent allelopathic substances which inhibit competition. The dead material provides an excellent fuel for fires, and further it is fire-stimulated, increasing cover dramatically with each fire.
    "Perennial tall bunchgrass with tufted stems, 50-100cm tall, branches 1-3 at node. Leaves: Leaf-sheaths more or less tuberculate-hirsute on the margins with long usually lax hairs; ligule yellow-brown, membranous, truncate, white-fringed at edge; blades 40cm long or less, 2-5mm wide, rough or roughish, hirsute on the upper surface near the base; spathes 3-5cm long, extending beyond the racemes. Racemes: 2 (-3-4), 2-3cm long. Spikelets: Sessile spikelet 3-4mm long, twice to half again as long as the internode, the awn straight, 10-15mm long; pedicellate spikelet wanting or rarely present as a minute scale, pedicel exceeding the sessile spikelet. Flowers: Either sessile and hermaphrodite, or stalked and staminate, sterile or not developed." (Cronk and Fuller, 1995. In PIER, 2003)
    Similar Species
    Themeda australis, Themeda triandra

    Occurs in:
    natural forests, range/grasslands, ruderal/disturbed, scrub/shrublands, wetlands
    Habitat description
    Subhumid to humid subtropical areas on a wide range of soils, (PIER, 2003). From sea level to 1,600m in Hawaii, (Smith). Dried material contributes to fire hazard, and reproduction is encouraged by fire, (PIER, 2003). On infertile soils (low in nitrogen or phosphorous), A. Virginicus acts as a long-lived competitor, (Uchytil, 1992). Work in Tennesse showed broomsedge to have an average lifespan of 3-5 years and that all plants died within 7 years.
    General impacts
    This perennial bunchgrass sometimes forms continuous cover in boggy, open mesic and dry habitats. It releases highly persistent allelopathic substances (Rice 1972, In Smith). The dead material provides an excellent fuel for fires. It is fire-stimulated; its cover increases dramatically with each fire (Smith, Parman, and Wampler, 1980, in Smith). In areas where it occurs, both fire intensities and acreage burnt have increased, (Smith). Work in Oklahoma in the US showed no change with a single spring burn, an increase with two spring burns, and that it was drastically reduced with a summer or fall burn when soil conditions were dry. Andropogon virginicus invades forest and other native vegetation, along tracks, (ESC, undated). Nearly pure stands can persist as a result of competition and allelopathy, (Uchytil, 1992).
    A serious problem in Hawai‘i - major infestations occur on the windward plain and Pupukea areas of O'ahu, overgrazed ridges in east Moloka'i, and the Puna and Ka'u regions, (PIER, 2003). On French Polynesia exclusion list, (PIER, 2003). Because it retains the phenology of its native habitat, the southeastern United States, its growth is out of synchrony with Hawaii's climatic pattern. It is dormant during the rainy season, which leads to increased erosion in some areas (Mueller-Dombois, 1973 in Smith).
    Geographical range
    Native range: North America, Central America, West Indies.
    Known introduced range: Hawai‘i, Australia, New Zealand, Midway Atoll and French Polynesia.
    Local dispersal methods
    Hikers' clothes/boots: The seed is well adapted to catch in clothing, (PIER, 2003).
    On animals: The seed is well adapted to catch in wool (PIER, 2003).
    Translocation of machinery/equipment (local): May also be spread on mud on machinery. (PIER, 2003)
    Management information
    Preventative measures: A Risk assessment of Andropogon virginicus for Australia was prepared by Pacific Island Ecosystems at Risk (PIER) using the Australian risk assessment system (Pheloung, 1995). The result is a score of 13 and a recommendation of: reject the plant for import (Australia) or species likely to be a pest (Pacific).
    Broomsedge tolerates low fertile soils with low soil ph and P and K (Peters and Lowance, 1974) Note: Broomsedge does not tolerate close continuous grazing. Neel (1936), Klingman (1971), and Butler (2000) reported cattle grazed broomsedge readily when fertilised and mowed
    The seed is well adapted to catch in wool and fur as well as in clothing (PIER, 2003). May also be spread on mud on machinery, (PIER, 2003). Seeds are also dispersed by wind and readily establish on exposed soil, (Uchytil, 1992). Each flowering culm may have as many as 50 racemes, and each raceme 8 to 12 spikelets. Germination is relatively high after cold stratification. (Uchytil, 1992)
    Lifecycle stages
    Flowering begins when plants are 2 or 3 years old, and continues thereafter (Uchytil, 1992).
    Reviewed by: Dr. Twain Butler, Extension Agronomist Texas A&M AREC. USA
    Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG)
    Last Modified: Tuesday, 29 August 2006

ISSG Landcare Research NBII IUCN University of Auckland