More info for the terms: association, bog, codominant, constancy, cover, fen, fern, forbs, frequency, mesic, muskeg, shrub, succession, xeric
General site characteristics: Green muhly occurs primarily in wetlands and riparian areas, from lowlands to subalpine meadows, but it also occurs in drier upland plant communities and disturbed areas. Green muhly frequents bogs and low grounds throughout its distribution [47] but occurs at elevations up to 11,000 feet (3,400 m) [5]. It occurs on a range of site types, from swamps, wet meadows, streambanks, and moist canyon bottoms [35] to rocky slopes, prairies, sandstone outcrops, and forest ecotones [5]. Throughout most of its range, green muhly is classified as a facultative wetland species: one that usually occurs in wetlands but is occasionally found in nonwetlands [81].
Green muhly seems to be a plant of generally low abundance but with high tolerances. It is frequently described in "waste places" [35,77] and disturbed areas associated with human settlement, including the margins of cultivated fields and along irrigation ditches, railways, and roadsides [5]. It is found in both moist and dry soils in all soil textures [77]. It occurs in both open plant communities (e.g., [71,83]) and in forest or woodland understories (e.g., [59,77,78]).
Site characteristics and plant communities by region: Green muhly seems to be most common in wetlands in the Great Lakes region, and in riparian areas in the Northern Great Plains and Southwest. It is also commonly described as occurring in disturbed areas throughout its range. Green muhly is rarely a dominant species where it occurs, and typically has relatively low cover.
Canada: In Alberta green muhly occurred in a bog dominated by bog birch (Betula glandulosa) near the McLeod River. Green muhly was abundant in depressions in areas where ridges were dominated by shrub vegetation, and saturated or submerged depressions were carpeted with mosses and grasses. Green muhly also occurred in a tamarack (Larix laricina)-bog birch-Cosson’s limprichtia moss (Limprichtia cossonii) moor near Jolicoeur Lake and under tamarack in a calcareous muskeg [54].
Great Lakes: Green muhly occurs primarily in the western portion of the Great Lakes Region, where it is typically found in wet grasslands and peatlands near lakes, and less commonly in drier communities [10]. For example, wet prairies in Wisconsin may be dominated by bluejoint reedgrass (Calamagrostis canadensis), prairie cordgrass (Spartina pectinata), big bluestem (Andropogon gerardii), and green muhly [10]. Green muhly was a characteristic species in western bracken fern (Pteridium aquilinum)-grasslands in northeastern Wisconsin [10,84,85]. In Dane County, Wisconsin, green muhly was a minor component in a reedgrass-sedge (Calamagrostis spp.-Carex spp.) association and in a hay meadow where tamarack had been removed by grubbing. It was more widespread, though still relatively infrequent, in a drained, reedgrass-sedge community succeeding to a big bluestem-dominated community [19]. Green muhly was "especially conspicuous" throughout a sedge mat community dominated by American woollyfruit sedge (Carex lasiocarpa var. americana) surrounding a lake at Itasca State Park, Minnesota, although it had relatively low abundance [57]. Green muhly was abundant in a bog in northern Illinois [18].
Some authors also note green muhly occurrence in disturbed sites and upland communities in the Great Lakes region such as moist, shaded roadsides and other disturbed areas at the Sand Ridge State Forest, Illinois [56]; dry soil along railroads in Michigan [86]; and dry prairies, rocks, and bluffs in Wisconsin [17]. Green muhly occurred in a native oak (Quercus spp.) savanna in eastern Minnesota [3] and was thought to be a component of the groundlayer vegetation in oak savanna in southern Wisconsin [4]. It occurred on limestone prairie in southern Wisconsin, and based on a review of pertinent literature and observations by ecologists in the area, green muhly was thought to prefer mesic, dry-mesic, and dry sites [4]. In Crex Meadows in Wisconsin, green muhly occurred in northern pine-hardwood communities, dominated primarily by jack pine (Pinus banksiana) and northern pin oak (Q. ellipsoidalis) [85]. It was present in both the aboveground vegetation and the seed bank of an old field in southwestern Ohio that was dominated by eastern cottonwood (Populus deltoides), hackberry (Celtis occidentalis), American elm (Ulmus americana), and boxelder (Acer negundo) in the overstory, and by several introduced grasses, including Canada bluegrass (Poa compressa) and Kentucky bluegrass (P. pratensis), in the herb layer [53].
Northern Great Plains: Green muhly is most common in wet meadows, shores, and stream banks in the Northern Plains [50], such as moist meadows and low ground throughout Montana [8]; subirrigated meadows and stream margins in Wyoming [26]; riparian and wet grassland communities and moist microsites in prairies in Nebraska [62,75]; and floodplains along the Little Missouri River and its major tributaries in western North Dakota [29,87]. It is sometimes mentioned on dry sites (e.g., [12,13]) and disturbed areas (e.g., [24,50,75,76]), especially roadsides (e.g., [24,73]).
Green muhly is rarely a dominant or codominant species, with a few exceptions. It was among the dominant understory species on wet floodplains supporting relatively undisturbed, deciduous forests with closed canopies in Iowa [20]. It averaged 3.82% cover and codominated with sedges in at least one stand of wet tallgrass prairie in Iowa and eastern Nebraska. However, it had greater cover in mesic and wet-mesic communities with impeded drainage, where it had an average cover of 7.42% and 7.48%, respectively [91]. The greatest canopy cover reported for green muhly in the available literature, 40% (range 0-40%), was in disturbed and/or early to mid-seral stands of the boxelder/chokecherry (Prunus virginiana) habitat type in central and eastern Montana. This habitat type occupies woody draws that may occasionally be flooded by overland flows on terraces, fans, or floodplains along streams, rivers, lakes, springs, and ponds. Sites range in elevation from 2,100 to 4,000 feet (640-1,219 m) [30].
While green muhly is widespread in riparian communities in the Northern Plains, it typically has low abundance (<10% cover) and is rarely a community dominant. For example, green muhly was widespread in wooded draws studied in southern Saskatchewan, though typically with low canopy cover (<2%). Its highest average canopy cover in the area (7.4%) occurred in balm-of-Gilead (Populus × jackii) communities where wooded draws narrowed. It averaged 2.8% canopy cover in the Bebb willow (Salix bebbiana) community, which was restricted to narrow, gravel stream channels in bottoms where draws widened. It averaged 1.4% canopy cover in the silver buffaloberry (Shepherdia argentea) community and ≤1% canopy cover in boxelder and chokecherry communities [51].
Green muhly occurs in several riparian plant communities dominated by eastern cottonwood, green ash (Fraxinus pennsylvanica), or quaking aspen (Populus tremuloides). In Montana, green muhly was more common in eastern cottonwood community types that represent grazing or browsing disclimaxes, and less common in eastern cottonwood communities that occurred on recent alluvial deposits and were relatively undisturbed by livestock or wildlife [30]. Green muhly was an important species (100% constancy and 8.3% average cover) in the understory of the green ash/western snowberry (Symphoricarpos occidentalis) habitat type in Theodore Roosevelt National Park, North Dakota. It occurred occasionally in the green ash/chokecherry habitat type in Theodore Roosevelt National Park [29] and in central and eastern Montana [30]. Green muhly occurred sporadically in the green ash-American elm community type in western North Dakota [87]. At the Niobrara Valley Preserve, Nebraska, green muhly is a species of wide distribution in the basswood-eastern redcedar-eastern hophornbeam-green ash (Tilia americana-Juniperus virginiana-Ostrya virginiana-Fraxinus pennsylvanica) association in narrow, spring-fed canyons [31]. Green muhly occurred in the quaking aspen/water birch (Betula occidentalis) habitat type on upper slopes at Theodore Roosevelt National Park [29] and the quaking aspen/Oregon-grape (Berberis repens) habitat type in the Custer National Forest in North Dakota [28].
Green muhly sometimes occurs in shrub-dominated communities, such as disturbed and/or early- to midseral stands of the silver sagebrush/western wheatgrass (Artemisia cana/Pascopyrum smithii) habitat type in central and eastern Montana [30] and in Theodore Roosevelt National Park [29]. This type represents one of the driest extremes of the riparian or wetland zone and is a disturbance-caused disclimax where site potential has changed due to heavy prolonged grazing. Sites are located in deep, loamy, alluvial soils or where overland flow and/or fine-textured soils allow for increased moisture availability. Green muhly occasionally occurs in other shrub-dominated community types representing grazing disclimaxes, including the chokecherry, Wood's rose (Rosa woodsii), and western snowberry community types. Kentucky bluegrass dominates the herb layer in these types [30]. In southern Saskatchewan green muhly occurred with ≤1% canopy cover in mixed-shrub and western snowberry communities, but reached 1.4% canopy cover in the silver buffaloberry community on alluvial deposits [51].
While green muhly is typically found in lowland sites in the Northern Plains, it also occurs in relatively drier upland communities. In the loessial region of northwestern Kansas and southwestern Nebraska, for example, green muhly was most common in lowland sites (32.5% absolute frequency), but it also occurred on level uplands, gentle upper slopes, and gentle lower slopes with <1% absolute frequency. It did not occur on steep slopes. It was most common on mesic sites (6.92% of the community composition and 0.33% basal cover), rarely occurred on dry-mesic sites (0.18% composition, 0.01% basal cover), and did not occur on dry or very dry sites [40]. It was recorded in tallgrass prairie sites in western Nebraska [39] and South Dakota [33]. At the Loess Hills Wildlife Area, Iowa, green muhly occurred in the aboveground vegetation and the soil seed bank in deciduous woodland and shrubland communities dominated by roughleaf dogwood (Cornus drummondii) and elms (Ulmus spp.). It also occurred in the soil seed bank in both native tallgrass (dominated by big bluestem and indiangrass (Sorghastrum nutans)) and midgrass (dominated by little bluestem (Schizachyrium scoparium) and sideoats grama (Bouteloua curtipendula)) grasslands and nonnative grasslands (dominated by Kentucky bluegrass and smooth brome (Bromus inermis)) in the area. It was either rare, absent, or not sampled in aboveground vegetation in these grassland communities [67]. Green muhly occurred sporadically in the bur oak (Quercus macrocarpa) community type in western North Dakota [87]. It occurred in one stand of the needle-and-thread grass/sedge (Hesperostipa comata-Carex) habitat type in southwestern North Dakota on gently rolling slopes of sandy uplands [34]. Green muhly was found in the soil seed bank in grasslands dominated by blue grama (Bouteloua gracilis), green needlegrass (Nassella viridula), needle-and-thread grass, prairie sandreed (Calamovilfa longifolia), and western wheatgrass at Theodore Roosevelt National Park [80].
Northern and Central Rockies: According to Rydberg [68], green muhly occurs in wet meadows in the subalpine and montane zones throughout the Rocky Mountains. However, publications describing habitats or site conditions for green muhly in the Northern and Central Rocky Mountains are lacking. One study noted green muhly among the pioneer vegetation 5 years after a severe fire in a subalpine fir/grouse whortleberry (Abies lasiocarpa/Vaccinium scoparium) habitat type in Yellowstone National Park [1]. Green muhly occurred in disturbed and/or early- to midseral stands of the silver sagebrush/western wheatgrass habitat type, which occurs at 5,600 feet (1,697 m) throughout central and eastern Idaho. Site conditions in this habitat type (e.g., deep, fine-textured soils, and/or periods of overland flow) increase moisture availability and sometimes result in a perched water table [25]. According to a flora of the Intermountain West, green muhly is infrequent in the area and occurs on dry ground such as drying meadows, rocky slopes, and in disturbed sites such as irrigation ditches and cultivated areas [9]. In riparian communities along the lower Yellowstone River, Montana, green muhly occurred at all stages of succession described as seedling, thicket, young cottonwood, mature cottonwood, shrub, and grassland stages. It also occurred in willow (Salix spp.)-shrub and green ash communities [6]. Green muhly occurred in ponderosa pine (Pinus ponderosa) forest on the Custer National Forest in southeastern Montana [42].
Southwest: Green muhly may occur in dry microsites in the Southwest but is most often described in moist microsites and riparian communities. For example, Colorado floras describe green muhly sites as rocky places in the sagebrush (Artemisia spp.) and quaking aspen zones [88] or rocky slopes, foothills, plains, gulches, and the bases of cliffs [89]. One study notes that green muhly occurred only on cliffs in their study area in the Colorado Front Range [23]. Another study in the foothills of the Colorado Front Range recorded green muhly in a mesophytic grassland association where it was commonly scattered along the moist soil of stream margins in open situations [83]. Green muhly is considered a wetland indicator species in New Mexico [60].
A study from the Black Canyon of the Gunnison National Monument along the Gunnison River in Colorado demonstrates green muhly's wide tolerance for soil moisture conditions. Green muhly was a dominant species in the cover type with intermediate soil moisture conditions. On flat areas of alluvial sediment along the river, 3 cover types were identified on the basis of species-occurrence data. These cover types differed in both inundation duration and soil particle size (P<0.0001). Green muhly was a codominant species in the scouringrush horsetail (Equisetum hyemale) cover type, which consisted of mesic to xeric herbs and grasses dominated by scouringrush horsetail, Canada bluegrass, creeping bentgrass (Agrostis stolonifera), green muhly, and western goldentop (Euthamia occidentalis). The substrate was primarily organic matter and sands; however, some plots were dominated by boulders. This cover type was typically found on middle and upper elevation gravel and cobble bars and was a relatively dry and infrequently inundated cover type. Green muhly also occurred in 57% of the plots in the common spikerush (Eleocharis palustris) cover type. This was the wettest cover type and was found from the channel edge up to low and middle elevation gravel bars and was frequently inundated. The substrate was variable and consisted primarily of cobbles and boulders with large fractions of silt, sand, and organic matter. Green muhly occurred in only 7% of the plots in the hairy false goldenaster (Heterotheca villosa) cover type, which consisted of largely of upland species and xeric grasses and was dominated by cheatgrass (Bromus tectorum), hairy false goldenaster, and sand dropseed (Sporobolus cryptandrus). This was the driest, least frequently inundated cover type, and had a substrate that was primarily sands, cobbles, and boulders. Green muhly was classified as a facultative upland species (1-33% occurrence in wetlands) [2], which is more consistent with its classification in the Intermountain Region, but not the Southwest [81].
Green muhly occurs in riparian forests throughout the Southwest, including both narrowleaf cottonwood (Populus angustifolia) and boxelder community types in southern Colorado, New Mexico, and Arizona. The narrowleaf cottonwood community type occurs at elevations ranging from 5,439 to 9,199 feet (1,658-2,804 m), and the boxelder community type occurs at elevations ranging from 4,879 to 7,119 feet (1,487-2,170 m) [78]. In northern New Mexico and southern Colorado, green muhly can occur in riparian forests in the narrowleaf cottonwood-Rocky Mountain juniper/sand dropseed (Juniperus scopulorum/Sporobolus cryptandrus) community type, which is characterized by mature, moderately open stands (40-60% cover). This community type occupies some of the driest sites in the floodplain, occurring mostly on sandy alluvial sediments; however, wetland indicator species such as green muhly, common rush (Juncus effusus), and fowl mannagrass (Glyceria striata) can occur [60].
Green muhly has been reported in a variety of other riparian types in the Southwest. For example, green muhly occurs in the narrowleaf willow/false quackgrass (Salix exigua/Elymus × pseudorepens) community type, which is associated with low-gradient rivers at elevations around 6,000 feet (1,825 m) in the upper Rio Grande watershed in New Mexico. This shrub community is dominated by moderate to dense canopies of narrowleaf willow with abundant false quackgrass in the understory. The nonnative saltcedar (Tamarix ramosissima) may be well represented but is not dominant. Soils are loamy or sandy-skeletal and are normally wet within 1.6 feet (0.5 m) of the surface [60]. Green muhly occurs with <1% cover and 25% constancy in the semiriparian ponderosa pine/Arizona walnut (Juglans major) habitat type, which occurs sporadically on alluvial terraces along perennial streams or large washes south of the Mogollon Rim in Arizona at elevations between 5,500 and 6,400 (1,680 and 1,950 m) [59]. At Wide Rock Butte in Canyon de Chelly National Monument, Arizona, green muhly occurred only in the one developed drainage. This area had deep soil (>3.3 feet (1m)) and dense vegetation consisting of prairie sage (Artemisia ludoviciana) and other forbs and grasses. The surrounding vegetation is a pinyon-juniper (Pinus-Juniperus) type [69].
Great Basin: Green muhly is rare in the Great Basin, apparently occurring in both dry and wet habitats. According to Kartesz [45], green muhly occurs in moist areas in canyons and meadows along streams and ditches at 3,500 to 5,500 feet (1,100-1,700 m). However, it is rare in Nevada and known only from the Ruby Mountains [45]. A habitat type publication from Nevada identifies green muhly as a component of the Wood's rose shrubland, which is said to occur in the foothills and plains of Montana, Idaho, Nevada, and eastern California, although no plots of this community type have been identified in Nevada [63]. The Utah flora indicates that green muhly occurs on dry to moist sites on open slopes, in hanging gardens, mountain brush, aspen, ponderosa pine, and meadow communities at 4,000 to 10,000 feet (1,220-3,050 m). It is also a weed of gardens [90]. A flora from the Uinta Basin, Utah, identifies 2 records of green muhly from dry, rocky slopes at 7,160 to 7,500 feet (2,180-2,280 m) [22].
Northwest: Green muhly's occurrence in the Northwest is confusing. One publication notes its occurrence in marl fen at the extreme northern part of Pend Oreille County, Washington [52]. However, floras from the Pacific Northwest suggest that while green muhly may occur on moist streambanks, irrigation ditches, and lake margins, it mainly occurs in dry, often rocky areas [37]. In fact, they distinguish green muhly from spiked muhly based on habitat: green muhly occurs on dry upland and disturbed sites, and spiked muhly occurs in moist areas [36].
Northeast: Information on green muhly site preferences in the Northeast comes exclusively from regional floras. Green muhly is said to occur on dry soil in New England [72], and is reported to occur in drier habitats than spiked muhly. Potential habitats include prairies, rock outcrops, open upland woods [21], meadows, rocky slopes, river shores, and occasionally wet meadows [55]. It may also occur along roads or in other disturbed sites [21] or "waste places" [55].