the Centre for Boreal Research. Americanus (native), of the family Poaceae, the grass family. (Saltonstall, P.M. Peterson, & Soreng) A. Haines When large-scale control is planned, any stands of native phragmites should be protected. Comment (max 1000 characters): Note: Comments or information about plants outside of Minnesota and neighboring states may not be posted because I’d like to keep the focus of this web site centered on Minnesota. State documented: documented Phragmites is also known as common reed, giant reed and canegrass. Phragmites australis subsp. Phragmites australis is a grass reed plant also known as the common reed. Phragmites australis, is commonly considered an invasive species in North America, but there are at least two lineages of the reed, an invasive lineage common to Europe and Asia (Phragmites australis subp. Although non-native Phragmites australis reigns supreme in terms of publicity, it is important remember that we also have stands of native Phragmites throughout the Great Lakes region. The native haplotypes are important components of wetland ecosystems, while a non-native haplotype introduced in the nineteenth century has become an aggressive invader. The invasive subspecies of phragmites (Phragmites australis) looks very similar to a native species (Phragmites americanus), and it is imperative that a stand be identified as invasive before implementing a management plan. A key and distribution maps to the three lineages are included. There’s a native Phragmites americanus that looks very similar, but is less robust and less inclined to spread than Phragmites australis, whose origins are in Europe. Phragmites australis americanus An Ornamental Grass You Won’t Want to Grow Standard. About Common Reed (Phragmites australis) 1 Nurseries Carry This Plant Add to My Plant List; Phragmites australis, the common reed, is a large perennial grass found in wetlands throughout temperate and tropical regions of the world.It is sometimes regarded as the sole species of the genus Phragmites, though some botanists divide Phragmites australis into three or four species and in … RI, No. the state. However, another subspecies of Phragmites – Phragmites australis subsp. Minnesota Environment and Natural Resources Trust Fund, sun; moist to wet soil; marshes, swamps, fens, sedge meadows, shores, swales, wet ditches. australis (non-native) and Phragmites australis subsp. Sida, 21:683-692 americanus. Until recently these two taxa were not distinguished, and efforts to eradicate the common reed may have impacted populations of the less common American reed. Gallic acid released by phragmites is degraded by ultraviolet light to produce mesoxalic acid , effectively hitting susceptible plants and seedlings with two harmful toxins. Trin. It can be difficult to distinguish between the native and invasive haplotypes while in the field, but many resources exist to help people identify which one they are dealing with. Upper stems are green, lower to mid stems are somewhat shiny and maroon to reddish brown, though the color may fade in winter. Invasive vs. American reed is the native close relative to the invasive common reed (Phragmites australis). If the plants are overwhelmingly dominant in an area, some positive benefits can be noted. americanus – the North American genotype has been described as a distinct subspecies, subsp. Phragmites australis is a wetland grass with a feathery plume at the tip of a tall, leafy stem, and is one of the most widely distributed flowering plants in the world. australis (non-native) and Phragmites australis subsp. With invasive Phragmites australis now pervasive throughout the majority of the Great Lakes region, it can be tempting to tackle every stem you encounter. Can you please help us? Native vs. Non-native. ex Steud. It currently has 3 recognized subspecies: one European ( subsp. It is in flower from July to September, and the seeds ripen from August to October. Note: when native and non-native County documented: documented Its scientific name is Phragmites australis subsp. altissimus (Benth.) Phragmites, as P. australis is commonly known, is a perennial grass that grows in wetland areas and can grow up to 15 feet in height. See Terms of Use and Privacy Policy. Go Botany: Native Plant Trust For more than 25 years I have observed Phragmites’effects on important habitats and attempted to control it without causing any harm to the habitats I work in, all of which support species and communities of conservation concern in Massachusetts. Evidence from fossilized dung of the ground sloth, phragmites was present in North America as long as 40,000 years ago and fossil phragmites seeds found in peat samples date back 3,500 years. Non-native Phragmites has been described as perhaps the most widely distributed and abundant grass on earth. Map of native plant purveyors in the upper midwest. americanus to species rank, Phragmites americanus, already accepted in some circles. Phragmites er ættkvísl fjögurra tegunda fjölærra grasa sem vaxa í votlendi í tempruð- og hitabeltis- svæðum um heiminn. Leaves drop off at the ligule at maturity (lower leaves in particular), leaving the sheath, which dries to tan and becomes loose around the stem, often falling off altogether at the node. Phragmites australis (Cav.) in part by the National Science Foundation. – heimsútbreiðsla; Phragmites japonicus Steud. americanus, native to fens, bogs and river shores within its North American range (Catling 2005) and more widespread in BC. americanus (Poaceae: Arundinoideae) in North America: Evidence from morphological and genetic analyses November 2003 SIDA 21(2):683-692 Phragmites australis in Northern Michigan Abstract Phragmites australis, or common reed, is represented by several subspecies (haplotypes) in North America. To reuse an Its scientific name is Phragmites australis subsp. Recognition of Phragmites australis subsp. Surrounding a floret is a pair of bracts (lemma and palea), the lemma narrowly lance-linear with a long taper to a pointed tip but not awned, 8 to 13.5mm long, the edges rolled in (involute), 3 to 7 veined; the palea is pale, half or less as long as the lemma and blunt at the tip. a sighting. americanus is … but this is a synonym. All rights reserved. berlandieri, and the nonnative common reed haplotype are distinguished morphologically by the Flora of North America and Blossey . ssp. australis ) and two North American (subsps. 2020 Do you know how aggressive the native subspecies can be? Web design and content copyright © 2006-2020 MinnesotaWildflowers.info. grown in the greenhouse at . This initiative is aimed at reducing the current threats posed by this aggressive invasive plant to biodiversity and Species at Risk (SAR) through habitat protection and restoration. 21, no. Native Plant Trust or respective copyright holders. Phragmites ” previously posted on the Weeds Gone Wild website. It most often forms either loose or localized colonies, which allow for the co-occurrence other species. Note: All comments are moderated before posting to keep the riff-raff out. Spikelets are purplish when young, somewhat flattened, with 3 to 11 florets. americanus. Brackish or salt marshes and flats, fens, fresh tidal marshes or flats, shores of rivers or lakes. americanus is a … Phragmites australis subsp. It is considered an invasive plant that causes problems for wetland communities by creating a monoculture which outcompetes the native vegetation for space. This field guide presents the most current information available on the origin, distribution, taxonomy, genetics and morphological differentiation of native and introduced forms of Phragmites australis. Americanus (native), of the family Poaceae, the grass family. Extent of range: According to the Great Lakes Phragmites Collaborative , invasive phragmitis is now found in the contiguous United States (all 48 states) and all of the Canadian provinces. All images and text © However, through periodic management, it is possible to maintain phragmites infesta-tions at levels that allow for regeneration of native wetland plant communities and protection of fish and wildlife habitat. In Montana, Phragmites australis ssp. berlandieri, and the nonnative common reed haplotype are distinguished morphologically by the Flora of North America and Blossey . The stalk between florets (rachilla) is densely covered in silky white hairs up to 1cm long. It currently has 3 recognized subspecies: one European (subsp. Phragmites australis americanus) Figure 2. Its inflorescence is usually sparser than non-native Phragmites, as are most patches where it grows. (Saltonstall, P.M. Peterson, & Soreng) A. Haines, Show Phragmites (Phragmites australis) Phragmites are an invasive species to the United States and the origin of their arrival is unknown, however, their rapid spread throughout North America has affected ecosystems and property values alike. Phragmites, as P. australis is commonly known, is a perennial grass that grows in wetland areas and can grow up to 15 feet in height. You can’t drive along a highway in many parts of North America without seeing mile after mile of a very attractive grass. Tidal river shores, fens, lake shores. berlandieri is found in the southern US from California to Florida and into Mexico. you. americanus has co-evolved with other native flora and fauna, has existed in Wisconsin for thousands of years, and does not typically reduce biodiversity or cause ecological disruption where it occurs. The European subspecies was probably introduced by accident in the 18th or 19th century; it is quite invasive and has spread across the continent. The Go Botany project is supported Trin. Figure 1. Phragmites is also known as common reed, giant reed and canegrass. & Schult. • 2 As new information is available, discriminating morphological characteristics are updated at www.invasiveplants.net [ 26 ]. The table below will indicate the characteristic differences between the two. Phragmites australis (Cav.) americanus australis (non-native) and Phragmites australis subsp. Americanus (native), of the family Poaceae, the grass family. Both sub-species can be found in Nebraska. The head persists into winter. state. Similar species: Native Phragmites (Phragmites australis ssp. Subsp. ), please check the links and invasive species pages for additional resources. G Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. americanus has high genetic diversity, and both cpDNA and nuclear DNA reflect genetic structuring among Atlantic Coast, Midwest, and West populations (Saltonstall 2003a, b).It has higher cpDNA haplotype diversity than other lineages in North America or those in European populations. Its scientific name is Phragmites australis subsp. It usually gets about 6.5 feet high, though it can be taller in rich soils. Phragmites australis is a wetland grass with a feathery plume at the tip of a tall, leafy stem, and is one of the most widely distributed flowering plants in the world. P. australis americanus. Trin. Phragmites is also known as common reed, giant reed, or canegrass. Americanus (native), of the family Poaceae, the grass family. Thanks for your understanding. Arundo occidentalis Sieber ex Schult.. Arundo palustris Salisb.. Arundo phragmites L.. Arundo pseudophragmites Lej.. Arundo pumila (Willk.) ex Steud. Invasive phragmities (Phragmites australis australis), a European common reed, is a tall, perennial grass that is invading wetlands, roadside ditches and agricultural lands across Oxford County. those considered historical (not seen in 20 years). : SIDA Contributions to Botany, vol. subspecies (americanus) from the invasive subspecies (australis). Have you seen this plant in Minnesota, or have any other comments about it? The World Checklist of Selected Plant Families, viðhaldið af Kew Garden í London, viðurkennir eftirfarandi fjórar tegundir:. Native vs. Non-native. Help support this site ~ Information for sponsor opportunities. When large-scale control is planned any stands of native Phragmites … Leaves are alternate, 8 to 24 inches long, 1/3 to 1½ inches (8 to 40mm) wide, green to yellowish-green, flat, hairless and mostly smooth on both surfaces, with a long taper to a pointed tip. Phragmites australis, known as common reed, is a broadly distributed wetland grass growing nearly 20 ft (6 m) tall.. Taxonomy. Its scientific name is Phragmites australis subsp. Non-native: introduced Its scientific name is Phragmites australis subsp. americanus, P. a. var. All Characteristics, the inflorescence axis is arched or curved outward, the panicle is somewhat to very congested (crowded), and the branches may not be clearly seen without close inspection, the panicle is somewhat to very spread out, with clearly-evident branches. Native Phragmites australis ssp. Pick an image for a larger view. ex Steud. Florets dry to tan and drop away when mature, leaving the glumes behind persisting on the stalk with the lowest part of the hairy rachilla, giving the remaining seed head a feathery look. americanus. Phragmites americanus It is sometimes regarded as the sole species of the genus Phragmites, though some botanists divide Phragmites australis into three or four species and in particular the South Asian Khagra Reed (P. karka) is often treated as distinct. We depend on The Ontario Phragmites Working Group (OPWG) is composed of dedicated people with an interest in working together to facilitate effective management of invasive Phragmites in Ontario. americanus, and; Phragmites australis – the Eurasian genotype is sometimes referred to as subsp. Native common reed – americanus: Leaf sheaths not or loosely attached to … post Subsp. The American Common Reed, Phragmites australis americanus, is a native plant to almost all of North America, except Alaska, the Yukon, and much of the Northwest Territory. australis (non-native) or Phragmites australis subsp. in 20 years). australis. Phragmites australis( , ) also known as common reed, ... Before attempting to control Phragmites, it is important to be able to distinguish the native Phragmites . At the base of a spikelet is a pair of bracts (glumes) that are narrowly lance-shaped with a long taper to a pointed tip, 1-veined, the lower glume 3 to 7mm long (typically more than 4), the upper 5.5 to 11mm (typically more than 6). It is not an invasive plant. Grains (seeds) are 2 to 3 mm long but rarely mature. 2) the native Phragmites australis subsp. An email address is required, but will not be posted—it will only be used for information exchange between the 2 of us (if needed) and will never be given to a 3rd party without your express permission. Phragmites / Common Reed. unintentionally); has become naturalized. North American reed grass (P. australis americanus). Arundo aggerum Kit.. Arundo australis Cav.. Arundo barbata Burch.. Arundo donax Forssk.. Arundo egmontiana Roem. Phragmites australis subsp. Both sub-species can be found in Nebraska. During the growing season it can reach over 15 feet tall, and has dark green leaves with a large purple-brown flower head. Phragmites australis subsp. It is in the family Poaceae (Grass family). Branching clusters, taller than wide, 6 to 14 inches long, lance-oval in outline, the main branches spreading to arching, sometimes nodding over to one side of the stem particularly as they dry. American reed. americanus) has smooth, flexible stems, often with shiny, round, black spots (a fungus). but this is a synonym. grown in the greenhouse at . americanus - native Family: Poaceae (Grass family) Native vs. Non-native. Native vs. Non-native. RESUMEN Se describe una nueva subespecie nativa Phragmites australis subsp. ex Steud. Briana, while the native reed can form fairly large colonies, it plays with its neighbors much better than the invasive non-native. americanus (native). Similar species: native Phragmites (Phragmites australis subsp. Phragmites australis: middle and upper internodes of stem dull and tan during the growing season and ligules mostly 0.4-0.9 mm long (vs. P. americanus, with the middle and upper internodes of stem shiny and red-brown to dark red-brown during the growing season and ligules 1-1.7 mm long). Phragmites australis (Cav.) Leaves are blue-green, 15 to 20 inches long, and one to one and a half inches wide. Both sub-species can be found in Nebraska. Both sub-species can be found in Nebraska. australis) and a non-invasive native lineage in North America (Phragmites australis subp. Funding provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources. With a little training this native subspecies can be differentiated from the exotic subspecies, australis.Populations form small, somewhat dense, and almost monotypic stands. Phragmites australis ssp. Additional work is needed to morphologically distinguish the introduced from Gulf Coast lineages. Reed grass (Phragmites australis) is a 1.5 to 5 m tall perennial grass commonly found in riparian areas and along the edges of wetlands. americanus Saltonstall, Peterson & Soreng; the Gulf Coast native strain became P. australis ssp. The two subspecies differ in growth form; the native subsp. Your email address: (required) The two subspecies are separated on the basis of glume length, culm/stem colour, leaf colour, and habitat. CT, MA, ME, The two subspecies are separated on the basis of glume length, culm/stem colour, leaf colour, and habitat. In Montana, Phragmites australis ssp. populations both exist in a county, only native status Where in Minnesota? americanus. Phragmites australis is a PERENNIAL growing to 3.6 m (11ft) by 3 m (9ft) at a fast rate. australis is causing serious problems for many other North American hydrophyte wetland plants, including the native Phragmites australis subsp. australis generally forms very dense stands, choking out most other species. americanus is native and scattered across many western, central, and northeastern counties. FIELD OBSERVATIONS Over several years the writer has maintained close familiarity americanus (Poaceae: Arundinoideae) in North America: evidence from morphological and genetic analyses. named Phragmites australis ssp. INTRODUCTION. ssp. Found this plant? Arundo naga J.König ex Steud.. Arundo nigricans Mérat. the Centre for Boreal Research. A second genetic type designated as the ‘Gulf’ type is native to Mexico and Central America and cryptogenic to the southern U.S., but it is clearly spreading along the southern tier of states. americanus (Poaceae: Arundinoideae) in North America: evidence from morphological and genetic analyses Journal/Book Name, Vol. VT. americanus Saltonst., P.M. Peterson & Soreng Show All Show Tabs American common reed Saltonstall & Hauber; and the non-native strain remained P. australis ssp. americanus is a beneficial wetland species. Phragmites, pronounced with a short ӑ, long ī and a long ē, is derived fr… donations to help keep this site free and up to date for Its inflorescence is usually sparser than non-native Phragmites, as are most patches where it grows. evidence (herbarium specimen, photograph). Native Phragmites The invasive subspecies (australis) of Phragmites is similar to a native species (subspecies americanus), and it is imperative that a stand be identified before implementing a management plan. Both sub-species can be found in Nebraska. Native Phragmites australis subsp. Stems are smooth, unbranched, mostly erect, and typically form small, loose colonies from long rhizomes, though denser colonies may occur. A second genetic type designated as the ‘Gulf’ type is native to Mexico and Central America and cryptogenic to the southern U.S., but it is clearly spreading along the southern tier of states. americanus) has smooth, flexible stems, often with shiny, round, black spots (a fungus). Also covers those considered historical (not seen Similar species: native Phragmites (Phragmites australis subsp. I believe we have a pretty large stand of it on a new property on Lake Virginia in Excelsior, and would like to select adjacent plants accordingly. It is hardy to zone (UK) 5 and is not frost tender. Arundo filiformis Hassk.. Arundo flexuosa Brongn.. Arundo graeca Link. 1.  Invasive phragmities (Phragmites australis australis), a European common reed, is a tall, perennial grass that is invading wetlands, roadside ditches and agricultural lands across Elgin County. Invasive vs. native. An aggressive, nonnative variety of phragmites (Phragmites australis), Sheaths are smooth, the edges overlapping near the tip or not, and sometimes have short hairs along the edge. to exist in the county by americanus - native Family: Poaceae (Grass family) Native vs. Non-native. For details, please check with your state. Phragmites is also known as common reed, giant reed and canegrass. Reed grass (Phragmites australis) is a 1.5 to 5 m tall perennial grass commonly found in riparian areas and along the edges of wetlands. Recognition of Phragmites australis subsp. You can’t drive along a highway in many parts of North America without seeing mile after mile of a very attractive grass. americanus, and; Phragmites australis – the Eurasian genotype is sometimes referred to as subsp. Take a photo and Native Phragmites The invasive subspecies (australis) of Phragmites is similar to a native species (subspecies americanus), and it is imperative that a stand be identified before implementing a management plan. However, they are relatively easy to distinguish, and genetic studies confirm these morphological differences. Phragmites australis Conservation status Least Concern Scientific classification Kingdom: Plantae Clade: Tracheophytes Clade: Angiosperms Clade: Monocots Clade: Commelinids Order: Poales Family: Poaceae Genus: Phragmites Species: P. australis Binomial name Phragmites australis Trin. americanus) Origin: The invasive plant was introduced to the east coast in the 1800s and has been expanding westward. Copyright: various copyright holders. australis page for more images and additional information on this invasive pest. The most apparent distinguishing field character is that the middle and upper stem internodes of American reed are smooth, shiny and red-brown to dark red-brown during the growing season. Invasive vs. native. Phragmites australis subsp. Most of the records in the Bell Herbarium have no subspecies designation but are assumed to be the native, the older records in particular. Phragmites are a clonal grass species with woody, hollow centers that are difficult to fully tear apart. americanus is native and scattered across many western, central, and northeastern counties. americanus is widespread in North America, but its national distribution is not altogether clear since the separation of subspecies is more or less a recent thing. See the glossary for icon descriptions. Phragmites australis americanus An Ornamental Grass You Won’t Want to Grow Standard. In either case, Phragmites australis is not likely to be confused with other grasses in Minnesota—it is the tallest grass in the state, though there are other tall grasses with feathery plumes in the nursery trade, such as Pampas Grass and Giant Miscanthus, but have not naturalized here. Older references do not distinguish them, but there are a number of key differences now known between subsp. Recognition of Phragmites australis subsp. americanus – the North American genotype has been described as a distinct subspecies, subsp. North American reed grass (P. australis americanus). americanus Saltonstall, 
P.M. Peterson, & Soreng altissimus (Benth.) australis is a cosmopolitan wetland grass that is invasive in many regions of the world, including North America, where it co-occurs with the closely related Phragmites australis subsp. NC. For example, the Muskrat, Mallard, Wood Duck, Canadian Goose, and Differential Grasshopper all consume Phragmites as a food source. australis (non-native) and Phragmites australis subsp. The following table can be used to help established phragmites, complete eradi-cation may not be achievable. Recent studies have characterized morphological distinctions between the introduced and native stands of Phragmites australis in North America. Phragmites australis, the common reed, is a large perennial grass found in wetlands throughout temperate and tropical regions of the world. Phragmites australis in Northern Michigan Abstract Phragmites australis, or common reed, is represented by several subspecies (haplotypes) in North America. Phragmites is also known as common reed, giant reed and canegrass. Photos by K. Chayka taken in Anoka, Chisago, Mahnomen and Polk counties and in North Dakota. Also covers americanus. The introduced species, Phragmites australis subspecies Australis is the species that grows rapidly. In contrast, native Phragmites australis ssp. Phragmites australis subsp. Eurasian common reed in late summer. Phragmites, though invasive, actually coexist with numerous species. Spikelets (flower clusters) are single at the ends of slender stalks that are appressed to slightly spreading from the branch. The genus Phragmites of family Poaceae comprises of the most common perennial, rhizomatous, stoloniferous and tall (2.0–6.0 m) grasses, viz., Phragmitesaustralis, P. karka, P. communis, P. longivalvis, P. maxima and P. prostrata (Poonawala et al. Phragmites australis subsp. The native haplotypes are important components of wetland ecosystems, while a non-native haplotype introduced in the nineteenth century has become an aggressive invader. August 30, 2018 – Etienne Herrick, USGS Great Lakes Science Center. Phragmites australis subsp. P. australis americanus. Saltonstall K, Peterson PM, Soreng RJ, 2004. Phragmites australis subsp. is shown on the map. Journal of the Botanical Research Institute of Texas, 1(1):385-388. Invasive vs. Invasive phragmites (pronounced “frag-my-teez”) differs from its native counterpart (Phragmites australis americanus) by growing in extremely dense stands crowding out other species. Phragmites australis americanus) Figure 2. ex Steud. australis and americanus: See photos below for comparisons of most of these traits, and the subsp. americanus Saltonstall, P.M. Peterson & Soreng. When large-scale control is planned any stands of native Phragmites … Discover thousands of New England plants. The table below will indicate the characteristic differences between the two. The ligule (membrane where the leaf joins the sheath) is .4 to 1mm long with a fringe of hairs along the top edge, the hairs occasionally long but usually short; ligules are somewhat fragile and often shred before long. to exist in the state, but not documented to a county within Photos courtesy Peter M. Dziuk taken at various locations across Minnesota and in North Dakota. It is considered an invasive plant that causes problems for wetland communities by creating a monoculture which outcompetes the native vegetation for space. 2) the native Phragmites australis subsp. .) Both sub-species can be found in Nebraska. Exact status definitions can vary from state to berlan-dieri (Fourn.) Phragmites australis is a grass reed plant also known as the common reed. As new information is available, discriminating morphological characteristics are updated at www.invasiveplants.net [ 26 ]. americanus (Poaceae: Arundinoideae) in North America: Evidence from morphological and genetic analyses November 2003 SIDA 21(2):683-692 The North American native type of Phragmites australis has been designated as a separate subspecies: Phragmites australis subsp. In Canada and the U.S. the Phragmites australis subspecies Americanus species is native. In common reed by contrast, the middle to upper stem internodes are dull, ridged, and tan-colored during the growing season. Phragmites australis, known as common reed, is a broadly distributed wetland grass growing nearly 20 ft tall. image, please click it to see who you will need to contact. ssp. Phragmites australis subsp. The invasive subspecies of phragmites (Phragmites australis) looks very similar to a native species (Phragmites americanus), and it is imperative that a stand be identified as invasive before implementing a management plan. Notes on Phragmites australis (Poaceae: Arundinoideae) in North America. Its scientific name is Phragmites australis subsp. Similar species: Native Phragmites (Phragmites australis ssp. Americanus (native), of the family Poaceae, the grass family. Native Phragmites australis subsp. australis. Native vs. Non-native. INTRODUCTION. The species is hermaphrodite (has both male and female organs) and is pollinated by Wind. With a little training this native subspecies can be differentiated from the exotic subspecies, australis.Populations form small, somewhat dense, and almost monotypic stands. Figure 1. Nodes are green to purplish, smooth or with a few fine hairs along the upper edge. The North American native type of Phragmites australis has been designated as a separate subspecies: Phragmites australis subsp. americanus and berlandieri), though there is talk of raising subsp. americanus, native to fens, bogs and river shores within its North American range (Catling 2005) and more widespread in BC. americanus, P. a. var. Phragmites americanus: middle and upper internodes of stem shiny and red-brown to dark red-brown during the growing season and ligules 1-1.7 mm long (vs. P. australis, with the middle and upper internodes of stem dull and tan during the growing season and ligules mostly 0.4-0.9 mm long). Non-native Phragmites, also known as common reed, is an extremely tall wetland grass.
2020 phragmites australis vs americanus