Typha x glauca
(hybrid cattail)

T.latifolia and T. angustifolia hybridize to form T. x glauca, a highly productive emergent wetland macrophyte. This species spreads prolifically by rhizomes (often 4 m/year) after seedlings establish in disturbed vegetation, frequently forming monotypes that reduce wetland plant and animal diversity. T. x glauca thrives under eutrophic conditions and artificially prolonged hydroperiods. In North America, the spread of T. x glauca has closely paralleled the westward advance of T. angustifolia from the east coast. Although T. x glauca is present in both Europe and North America, it appears more invasive in the latter continent. T. x glauca could be economically useful; both parental species were eaten throughout Europe and North America, and leaves were used for weaving. In natural areas, either cutting, burning, or grazing, each followed by flooding, or herbicide, can provide short-term Typha control, but re-growth from rhizomes and a vast soil seed-bank complicate eradication.

Because T. x glauca is often confused with its parents, adequately assessing its distribution is difficult. T. x glauca may be present throughout the entire sympatric range of its parental species, including most of Europe (Smith, 1987), although it is most frequently reported in North America. One parent, T. latifolia, is native to North America, Eurasia, and parts of Africa, and it appears to have been naturalized in Australia, and perhaps in South America (USDA-ARS, 2008). T. angustifolia appears to have a similar but slightly restricted distribution due to climatic constraints.). Smith (1987) reports that many or all South-American collections of T. angustifolia and T. latifolia (e.g. Crespo and Pérez-Moreau, 1967) may in fact represent other species or hybrids. Typha’s center of endemism is Eurasia (Smith, 1967).

T. angustifolia appears to continue to expand in western North America (Galatowitsch et al., 1999), probably abetted by human-caused disturbance, road construction, and the application of deicing salts (Wilcox, 1982; Grace and Harrison, 1986; Smith, 1987). T. x glauca will likely spread concomitantly with T. angustifolia, since T. latifolia is already widespread. Smith (2000) argues that T. x glauca, and perhaps T. angustifolia, should be classified as noxious weeds in North America, but no such designation has been achieved. The potential for T. x glauca to become invasive on other continents (e.g. Europe, where both parental species are widely distributed) is unknown. Taxonomic confusion could lead to an under-representation of T. x glauca’s distribution, especially in places like Northern Africa, where both parental species are reported to be present. Other aggressive Typha species (e.g. T. domingensis) are likely to be more problematic as invaders in tropical and sub-tropical climates.

T. x glauca can invade most wetland community types (including marsh, sedge meadow, shrub- carr, fen, lacustrine and riparian wetlands), as well as anthropogenic habitats where soil is periodically flooded (roadside ditches, irrigation canals, stormwater retention basins). T. latifolia is the only Typha species traditionally associated with undisturbed wetlands of Midwestern North America, while T. angustifolia is more prevalent in disturbed, saline, or artificial wetland habitats (Smith, 1967; Grace and Harrison, 1986). T. angustifolia is more tolerant of deeper water (> 15 cm) and saline soil than is T. latifolia, while T. x glauca tolerates a variety of water depths and salinity levels (McMillan, 1959; Grace and Wetzel, 1982). T. x glauca is most prevalent in areas with disturbed vegetation, bare soil, and altered hydroperiods. Typha spp. show a constitutive tolerance for soil and water contaminated by heavy metals (McNaughton et al., 1974).

T. angustifolia reduced the growth of mature Bulboschoenus fluviatilis (Torrey) Sojak by producing allelopathic chemicals (Jarchow and Cook, 2009). This mechanism, along with increased competition for light and nutrients, could explain a widespread pattern of reduced wetland plant diversity (including Carex spp., Schoenoplectus spp., and forbs) after T. x glauca invasion (Boers et al., 2007; Frieswyk and Zedler, 2007).

Genetics

Reproductive Biology

Physiology and Phenology

Nutrition

Associations

T. latifolia tolerates an extremely broad climatic spectrum, surviving winter minimums of -34°C in central Alaska as well as thriving in the tropics, and ranging in altitude from sea level to 2000 m (Smith, 1967; Grace and Harrison, 1986). T. angustifolia and T. x glauca, in contrast, might be limited where minimum temperatures are less than -13°C, but they can occupy a similar altitudinal range (0-1800 m). T. latifolia and T. angustifolia are more competitive in shallow < 15 cm) and deeper water, respectively (Grace and Wetzel, 1982), while T. x glauca appears to tolerate widely variable hydroperiods (Frieswyk and Zedler, 2007). T. x glauca can produce rhizomes extending 1 - 2 m below the soil surface, a trait that could increase drought tolerance (SG Smith, University of Wisconsin, USA, personal communication). T. x glauca also survives prolonged inundation. In a marsh flooded under 60 cm of water for 5 years, T. x glauca expanded while T. latifolia decreased (Harris and Marshall, 1963). Seedlings can tolerate anaerobic conditions. Mature plants, however, are intolerant of anaerobic conditions created when leaves are severed below water (Sale and Wetzel, 1983).

Animal feed, fodder, forage

• Fodder/animal feed
• Forage

Environmental

• Ornamental

General

• Sociocultural value

Human food and beverage

• Emergency (famine) food
• Flour/starch
• Food additive
• Seeds
• Vegetable

Materials

• Alcohol
• Baskets
• Fibre

T. domingensis is often sympatric with the parental species T. latifolia and T. angustifolia, and shares many characters with T. angustifolia (short, stiff compound pedicels, linear stigmas, presence of pistillate bracteoles, monad pollen). See Description section for characteristics of parent and hybrid. T. domingensis is distinguished by: light brown pistillate bracteoles similar in length to pistil hairs; normally colourless pistil hair apices; light-brown to cinnamon-coloured pistillate spike at anthesis, darkening slightly at maturity; leaf sheathes and adjacent blades with mucilage glands on the adaxial surface. Leaves are 7-18 mm wide, mature pistillate spikes are 13-26 mm wide, and the pistillate and staminate spikes are separated by 0-8 cm.

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Prevention is difficult given Typha’s prolific seed production. Reducing anthropogenic disturbance of soil and vegetation could reduce establishment, but disturbance by animals can still create germination sites, even in protected wetlands. Maintaining natural hydrology and reducing nutrient loads could reduce the density and spread of T. x glauca after its establishment (Boers, 2006). Maintaining consistently high water levels (> 1.2 m) in managed wetlands could prevent establishment from seed (Ivens, 1967). 

Most management of T. x glauca has focused on periodic density reductions to benefit waterfowl, rather than on permanent eradication (Apfelbaum, 1985). Seed banks often contain hundreds of viable seeds/m² (van der Valk and Davis, 1978b). Eradication would require yearly surveillance to kill new clones as they establish. Targeting T. angustfolia would reduce the spread of T. x glauca, but T. latifolia is normally a desirable component of North American wetlands. 

Burning, cutting, and grazing often reduce Typha spp. when followed by flooding. These methods remove leaf tissue that Typha requires to transport oxygen to underwater rhizomes. Deprived of oxygen, Typha respires anaerobically and accumulates ethanol as a toxic byproduct, causing mortality (Sale and Wetzel, 1983). High water levels are necessary to maintain Typha in an anaerobic environment after it re-sprouts. Water depths sufficient for complete mortality of Typha spp. after cutting have ranged from 26-80 cm, and experiments where water levels varied spatially showed increased re-growth in shallow water relative to deeper water (Shekhov, 1974; Beule and Hine, 1979; Murkin and Ward, 1980; Mallik and Wein, 1985; Ball, 1990). Cutting Typha while ramets are flowering and rhizome carbohydrate reserves are low reduces re-growth (Linde et al., 1976; Singh et al., 1976). Fires in flooded wetlands do not normally reduce Typha, probably because underwater leaf tissue is not damaged (Mallik and Wein, 1985; Grieco et al., 2005; Lee et al., 2005). In drained wetlands, fire can sometimes reduce Typha by damaging rhizomes directly (Mallik and Wein, 1985). Soil-burning fires can benefit Typha by increasing nutrient availability (Newman et al., 1998; Smith and Newman, 2001), but post-fire nutrient pulses might only increase growth temporarily (Ponzio et al., 2004). Successive water-level drawdowns could favour sedges (e.g. Eleocharis spp.) over Typha, as occurred in a T. domingensis marsh in Brazil (Palma-Silva et al., 2005). Draining and bulldozing provides destructive but effective control (Parsons and Cuthbertson, 1992). Sheep grazing decreased T. domingensis density in the soil seed bank (Nicol et al. 2007). 

Muskrats can decimate Typha (Kadlec et al., 2007), and herbivory by waterfowl and muskrats appears to increase following fire (Smith and Kadlec, 1985b). 

Many herbicides reduce Typha in the short-term, including glyphosate, amitrole-T, amino-triazole, or MCPA (Annen, 2007). These are effectively applied during flowering or when leaves begin to senesce (Beule and Hine 1979; Apfelbaum, 1985).

Harvesting Typha leaves can reduce re-growth, if followed by flooding. 

Dense Typha monotypes are visible on aerial photos and their expansion can be tracked over time (Boers, 2006; Frieswyk and Zedler, 2007; Hall, 2008).

Restoring natural hydrology, preventing prolonged flooding, and reducing nutrient loads should minimize Typha’s spread and ameliorate effects on diversity. In low-nutrient fens fed by groundwater, T. x glauca does not dominate or reduce plant diversity (Q Carpenter, University of Wisconsin, USA, personal communication, 2008).

The relative invasiveness of T. latifolia, T. angustifolia, and T. x glauca are often debated. Some argue that both parental species are invasive (Shih and Finkelstein, 2008). Other research suggests that T. latifolia is benign, and that T. x glauca is replacing its parental genotypes as well as other wetland species (Smith, 1987; Frieswyk and Zedler, 2007; Marburger et al., 2007). Mis-identifications could contribute to the debate over the relative invasiveness of T. latifolia versus T. x glauca. To what extent nitrogen and phosphorus limit growth is still unclear. Also, it is unclear what factors constrain the restoration of diverse wetland communities from T. x glauca monotypes (Boers et al., 2007; Hall, 2008).

30/04/08 Original text by:

Steven Hall, Nelson Institute for Environmental Studies, University of Wisconsin-Madison, USA