Botanical description: This description covers characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (e.g., [29,31,40,59,60,66,77,78,87,97]).
Form and architecture: Creeping jenny is a rhizomatous prostrate perennial forb [25,31,40] with evergreen to semi-evergreen foliage [45,66,78,105]. Its stems are slender, creep along the ground, and root at the nodes [37,45,60,66,78,105]. It is frequently described as a vine [20,36,100]. The stems can grow to 0.7 to 3.3 feet (0.2-1.0 m) long and 2 to 4 inches (5-10 cm) tall. The stems branch frequently and often form mats [28,29,36,40,97,105].
Photo courtesy of John M. Randall, The Nature Conservancy, Bugwood.org.Leaves: Creeping jenny leaves resemble small coins and give the plant its name. They are round to oval, opposite, simple, and 0.25 to 1.5 inches (0.6-3.8 cm) long [105]. They occur on short petioles [29,78]. The upper surfaces of the leaves have widely scattered, glandular, red to black dots [36,78].
Reproductive structures: Creeping jenny flowers are hermaphroditic [23,55]. They are typically solitary in the leaf axil [60,105]. The 5-lobed corolla is yellow with orange to black dots [29,31,36,37,60,105].
Although a fact sheet reported that the seed capsule has 5 cells [36], Uva and others [108] reported that creeping jenny fruit is a 1-celled spherical capsule that splits vertically when mature. Seeds weigh about 0.5 mg each [23,101]. A single seed capsule may contain 1 to 5 seeds [7]. Seeds are elliptic and about 1 mm long [108].
Roots: Creeping jenny roots are slender and fibrous [36,108]. Creeping jenny often forms new roots where leaf nodes come in contact with the soil [36,55,108].
Physiology: Creeping jenny is flood tolerant [112]. For more information, see Site Characteristics.
Creeping jenny is nonnative in North America, where it has a wide but discontinuous distribution. It occurs throughout the eastern United States east of the Mississippi River from Minnesota south to Louisiana, east to Georgia, and north to Maine. It occurs throughout southern Ontario, southern Quebec, and the Canadian Maritime provinces. It is also found in Nebraska, Kansas, and Colorado [105]. It occurs in the Pacific coastal states west of the Cascade Range in Washington and Oregon; in the northern Sierra Nevada in California; and in southwestern British Columbia and Vancouver Island [37,60,77,87]. Creeping jenny is more common in the central and eastern United States than in the West [37]. Plants Database provides a distributional map of creeping jenny.
Creeping jenny is native to Europe and western Asia [23]. See Bittrich [7] for a distributional map of creeping jenny in the species' native range. Creeping jenny was introduced from its native range to the United States for horticulture and as an ornamental ground cover [36,57,105]. It was present in the United States as early as 1739 [115]. It has escaped from cultivation and spread extensively. According to Mack [56,57], creeping jenny seeds were sold in the United States as early as 1833, and it was established outside cultivation in the United States by 1900.
Potential for postfire establishment and spread: As of 2011, there are no studies documenting the establishment and spread of creeping jenny after fire. Creeping jenny possesses some traits that are likely to allow it to survive and/or establish after fire (see Fire adaptations).
Preventing postfire establishment and spread: Because of creeping jenny's potential for long-distance seed dispersal via water, monitoring burned areas downstream of known creeping jenny populations for potential establishment is advised. Creeping jenny's potential short-term seed bank suggests that short-term monitoring may be necessary to limit creeping jenny establishment in burned areas.
Preventing invasive plants from establishing in weed-free burned areas is the most effective and least costly management method. This may be accomplished through early detection and eradication, careful monitoring and follow-up, and limiting dispersal of invasive plant propagules into burned areas. General recommendations for preventing postfire establishment and spread of invasive plants include:
For more detailed information on these topics, see the following publications: [4,9,30,106].
Use of prescribed fire as a control agent: General management guidelines for creeping jenny in the United States suggest that prescribed fire may be an effective method for controlling creeping jenny in fire-adapted plant communities [20,45]. However, fire effects on creeping jenny have not been reported in published literature as of 2011. Two sources recommended burning repeatedly for several years during spring or fall when creeping jenny is green but most native vegetation is dormant [20,45]. Prescribed fire is not likely to be a useful control measure for invasive species like creeping jenny in plant communities where fires are typically rare and native species are not fire-adapted, such as the forested wetlands of the Northeast. In contrast, prescribed fire may be an appropriate tool in herbaceous wetlands that support native species adapted to frequent fire (review by [22]).Fuels: As of this writing (2011) there was no information available regarding the fuel characteristics of creeping jenny.
FIRE REGIMES: In North America, creeping jenny occurs in a wide variety of plant communities that are characterized by a range of presettlement FIRE REGIMES. Creeping jenny is common in wetland and riparian floodplain areas, and FIRE REGIMES in these communities vary widely across the United States. For example, fire is unusual in northeastern riparian communities and may only occur in times of severe drought or wetland drainage. Riparian plants in these systems may not be fire-adapted. Long fire-return intervals are typical in wetlands of the Northeast (review by [22]). In contrast, fires are common in southeastern wetlands, which support large quantities of flammable, herbaceous vegetation that is well-adapted to frequent fires. Stand-replacement fires may occur in coastal wetlands at 1- to 10-year fire-return intervals (review by [96]). As of 2011, there was insufficient information to predict how creeping jenny might respond to these FIRE REGIMES. It is also unclear if or how creeping jenny may influence FIRE REGIMES.
See the Fire Regime Table for information on FIRE REGIMES of vegetation communities in which creeping jenny may occur. Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Creeping jenny establishes on lowland sites with a range of soil and climatic conditions. Creeping jenny occurs in full sun to full shade (see Shade tolerance) [36,113]. It commonly establishes on disturbed sites, though it may occur in relatively undisturbed native plant communities. A fact sheet reported that sites most vulnerable to creeping jenny establishment included floodplain forests and wetlands [20,61]. See Habitat Types and Plant Communities for detailed descriptions of some plant communities where creeping jenny occurs.
Soils: Creeping jenny grows best in moderately acidic to neutral [110], poorly drained soils [36,45,55,105].
Texture: Creeping jenny occurs in clays [16,55,93], silts [79,114], silt loams [44], sandy loams [2,41,42,44,93], loams, loamy sands [2], and sands [2,76,93]. Creeping jenny may also occur in areas dominated by boulders, stones, cobbles, or gravels [75,76,93].
Photo courtesy of Chris Evans, River to River CWMA, Bugwood.org.pH: Creeping jenny occurs in soils with pH ranging from 4.0 to 7.2 [2,41,44,110] but grows best in moderately acidic to neutral soils [110]. Along ditch banks in peat areas in its native range in the western Netherlands, creeping jenny cover and frequency were greater in moderately acidic to neutral (5.6-7.2 pH) soils (0.65% cover; 63% frequency) than in extremely acidic to strongly acidic (4.0-5.5 pH) soils (0.25% cover; 28% frequency) [110].
Soil fertility: Nitrogen and phosphorus are essential for plant growth. Since fire may result in substantial short- and long-term changes in availability of these nutrients (see [48] for a review), knowledge of creeping jenny's nitrogen and phosphorus requirements may yield important information regarding its potential for postfire establishment and spread. According to reviews, creeping jenny grows better in fertile soils [23,36]. In eastern cottonwood/black willow floodplain forests in Wisconsin, creeping jenny occurred in soils with a wide range of total nitrogen, phosphorus, and potassium, but it was most frequent in soils with the highest levels of these nutrients [2]. In contrast, in 28 restored and created wetlands throughout Illinois, creeping jenny decreased with increased nitrogen availability and also with wetland size (R²adj=0.21) [62]. Along ditch banks in peat areas in its native range in the western Netherlands, creeping jenny cover was greater in soils with low levels of applied nitrogen (0-250 kg/ha/year) (0.50% cover; 52% frequency) than in those with high levels of applied nitrogen (250-500 kg/ha/year) (0.33% cover; 26% frequency) [110]. In a peat moor in Somerset, England, creeping jenny showed a negative linear trend with increased nitrogen availability (P<0.05). Creeping jenny may have declined with increased nitrogen because of shading by tall grasses. The authors stated that creeping jenny is usually absent from areas with high nitrogen availability [67]. Creeping jenny is endomycorrhizal, and symbiotic arbuscular mycorrhizae increased resource uptake, growth, and flowering in creeping jenny in greenhouse experiments [35].
Moisture: Creeping jenny is most common on poorly drained, intermittently flooded soils (e.g., [41,42]). It also grows in shallow water and wet soil (e.g., [5,36,97]) and in dry soil (e.g., [97]). Along New River Gorge National River, creeping jenny occurred in wetlands, in areas frequently flooded during high water, in areas flooded occasionally, and in xeric communities [97]. Creeping jenny was considered an obligate wetland species in California and the Northeast and Central Plains regions of the United States and a facultative wetland species in the Southeast, North-central, and Northwest regions. Obligate species were those that occurred in wetlands >99% of the time, and facultative species were those that usually occurred in wetlands (67-99% of the time) but occasionally occurred in nonwetland habitats [82].
Creeping jenny appears to prefer intermittently flooded areas. In its native range in northeastern France, creeping jenny was found in periodically flooded (<1 month/year), occasionally flooded (1-3 months/year), and frequently flooded (>4 months/year) alluvial meadows, but was most frequent in occasionally flooded meadows [112]. In a sugar maple floodplain forest in Illinois, most creeping jenny plants occurred within 1.0 foot (0.3 m) of a streambank where flooding occurred frequently (flooded during 20% of observations), but plants also occurred as far away as 3.9 feet (1.2 m) from the streambank, where flooding occurred infrequently (5% of observations). Creeping jenny was absent from areas at greater distances from the streambank that rarely flooded (≤3% of observations) [6]. Along Little Otter Creek in Vermont, creeping jenny grew in poorly drained soils that were flooded each spring but did not grow in soils flooded for longer periods. Creeping jenny was absent from a narrow-leaved cattail (Typha angustifolia) marsh 16 feet (5 m) from the creek bank where soils were flooded or saturated in all but 1 to 2 months each year. At 33 feet (10 m) from the creek bank, the marsh abruptly transitioned into an open-canopy silver maple-swamp white oak (Quercus bicolor)-green ash forest with a shrubby understory. At greater distances from the creek bank, the tree canopy became more closed, the overstory trees became more diverse, flooding only occurred in spring, and creeping jenny became more common. It occurred with a density of 1,000 stems/ha at 49 feet (15 m) from the creek bank but 47,000 stems/ha at 164 feet (50 m) from the creek bank. At about 230 feet (70 m) from the creek bank, the forest transitioned to a closed-canopy yellow birch-sugar maple-American beech forest, and at 330 feet (100 m) from the creek bank creeping jenny density declined to 40,000 stems/ha [42]. In Stewart County, Tennessee, creeping jenny occurred in bottomland hardwood forests with soils that were generally saturated with water from winter to early summer [13].
Creeping jenny infrequently occurs in dry soils. In the Willamette Valley near west Eugene, Oregon, creeping jenny occurred in a seasonally flooded wetland prairie where standing water often occurred from November to April due to a shallow clay layer that impeded drainage. In the summer, soils dried out and became hard and deeply cracked, but creeping jenny survived to the end of the 3-year study [16]. Along the New River Gorge National River, creeping jenny occurred in Virginia pine-eastern redcedar-post oak woodland, a xeric community with exposed sandstone bedrock and an open canopy [97]. In Guthrie County, Iowa, creeping jenny occurred in dry and wet closed-canopy hardwood floodplain forests [27].
Climate: Creeping jenny occurs in temperate climates. As of this writing (2011), little is known about how climate affects creeping jenny distribution.
Average maximum and minimum temperatures and average annual precipitation of some sites with creeping jenny in North America Location Average annual temperatures (°C) Average annual precipitation (mm) Minimum Maximum Alexander County, Illinois 10.1 19.4 1,197 [5] Washington, DC 3.4 31.2 988 [24] Prince Georges and Charles counties, Maryland 5.9 19.6 1,144 [94] Stewart County, Tennessee 2.6 25.4 1,268 [13]In its native range in northeastern France, average annual rainfall was 36 inches (904 mm) and average annual temperature was 48.4 °F (9.1 °C) [112].
Elevation: In North America, creeping jenny occurs from sea level to at least 5,400 feet (1,600 m) [13,46,65,81]. Creeping jenny occurs from sea level to 597 feet (182 m) in its native range in the British Isles [23].
Topography: Creeping jenny generally occurs on level to gently sloping topography (e.g., [13,94,115]).
Impacts: A variety of fact sheets, government publications, and weed management guides suggest that creeping jenny populations form dense mats that may exclude other plants, including native species [28,29,36,40,97,105]. Creeping jenny's ability to dominate an area is attributed to its fast vegetative spread [28,36,61]. In floodplain forest of the lower Wisconsin River, creeping jenny was absent from a silver maple-green ash-elm (Ulmus spp.) floodplain forest in the 1950s but was one of the most frequent groundlayer species (second only to reed canarygrass (Phalaris arundinacea)) about 50 years later. The forest had become wetter over the 50 years, and there was an apparent loss of 2 native species possibly as a result of creeping jenny and reed canarygrass spread [32].
Although creeping jenny can occasionally become dominant in plant communities (e.g., [46,97]), it typically does not substantially modify natural habitats over large areas [68]. Most fact sheets, government publications, and weed management guides indicated that creeping jenny had no more than a moderate impact on native vegetation [20,68,83,104,117]. In a western Massachusetts silver maple-pin oak-green ash/buttonbush floodplain swamp forest, creeping jenny changed little in frequency and cover over approximately 27 years (1969: <0.5% cover, 2% frequency; 1996: 1% cover, 9% frequency) [39].
Control: Creeping jenny control may be complicated by its ability to sprout from stems and possibly roots following control treatments [20,45,105]. A fact sheet suggested that control efforts should focus on cessation of planting, management of existing infestations, and minimization of disturbance to forests, wetlands, and other natural communities [105]. Control effectiveness may depend on a program that integrates multiple management procedures such as herbicides, prescribed fire, seeding, and other techniques that decrease creeping jenny spread and favor desired species [45,105].
In all cases where invasive species are targeted for control, no matter what method is employed, the potential for other invasive species to fill their void must be considered [10]. Control of biotic invasions is most effective when it employs a long-term, ecosystem-wide strategy rather than a tactical approach focused on battling individual invaders [58].
Prevention: A fact sheet suggests that creeping jenny establishment may be prevented by minimizing soil disturbance [105]. Consumers should also avoid purchasing and planting creeping jenny [20,105].
It is commonly argued that the most cost-efficient and effective method of managing invasive species is to prevent their establishment and spread by maintaining "healthy" natural communities [58,89] (e.g., avoid road building in wildlands [103]) and by monitoring several times each year [43]. Managing to maintain the integrity of the native plant community and mitigate the factors enhancing ecosystem invasibility is likely to be more effective than managing solely to control the invader [38].
Weed prevention and control can be incorporated into many types of management plans, including those for logging and site preparation, grazing allotments, recreation management, research projects, road building and maintenance, and fire management [106]. See the Guide to noxious weed prevention practices [106] for specific guidelines in preventing the spread of weed seeds and propagules under different management conditions.
Fire: For information on the use of prescribed fire to control this species, see Fire Management Considerations.
Cultural control: Some sources indicate that creeping jenny may be controlled by establishing native grasses that shade out creeping jenny [45,105]. However, a fact sheet noted that creeping jenny can tolerate shading by taller grasses and forbs [36]. For more information on this topic, see Shade tolerance.
Physical or mechanical control: Activities that disturb creeping jenny plants, such as hand-pulling, may stimulate growth of new plants from fragmented stems and possibly roots or rhizomes. Management guidelines suggest that small infestations of creeping jenny may be eradicated by carefully digging out plants; however, all stems and roots must be removed for this technique to be effective [20,45,105]. In a seasonally flooded wetland prairie in the Willamette Valley, Oregon, creeping jenny cover declined 1 and 3 years after hand removal compared to pretreatment levels, but the difference was not significant. Creeping jenny cover also declined in control plots during the study [16].
Two sources reported that mowing does not control creeping jenny because the plants are typically too low to the ground to be impacted by mowing blades [45,105]. Moreover, physical disturbance by machinery may spread creeping jenny across fields. Fleming and Kanal [24] speculated mowing equipment may have spread creeping jenny from a lawn in Washington, DC, into nearby meadows and roadsides. In the Montezuma National Wildlife Refuge in central New York, creeping jenny was not present in grasslands succeeded to gray dogwood (Cornus racemosa), common buckthorn (Rhamnus cathartica), and multiflora rose (Rosa multiflora) prior to mowing, but creeping jenny cover ranged from 0.6% to 0.9% 3 years after mowing. Creeping jenny was not present in control plots [84]. Several researchers reported creeping jenny in areas mowed annually or more frequently (e.g., [13,34,92]). In a seasonally flooded tall oatgrass (Arrhenatherum elatius) grassland in the Netherlands, mowing in June and again in September increased creeping jenny frequency during 8 years. The authors suggested that repeated reduction of grasses increased the frequency of creeping jenny and other low-lying plants. Creeping jenny frequency decreased or remained unchanged in areas mowed annually. creeping jenny was absent in unmowed areas [70].
Some publications reported that creeping jenny may be killed by prolonged submergence in water [45,105]. However, a study in East Bohemia reported that creeping jenny survived flooding that covered the entire plant and that creeping jenny seed production was perhaps favored by the flooding [49]. For more information on this study, see Seed production. For more information on creeping jenny's soil moisture tolerance, see Site Characteristics.
Biological control: No biological controls of creeping jenny are known [45]. In the northern Front Range of Colorado, Al-Doghairi and Cranshaw [1] observed little to no visitation of creeping jenny by native arthropods typically used in biological control of pest plants (e.g., lady beetles (Coccinellidae), green lacewings (Chrysopidae), syrphid flies (Syrphidae), parasitic wasps (Braconidae), predatory wasps (Sphecidae), and techinid flies (Tachinidaea)).
Biological control of invasive species has a long history that indicates many factors must be considered before using biological controls. Refer to these sources: [109,118] and the Weed control methods handbook [102] for background information and important considerations for developing and implementing biological control programs.
Chemical control: Herbicides may control creeping jenny, although little information regarding the effectiveness of herbicides on creeping jenny was available as of this writing (2011) [45,105]. Herbicides are effective in gaining initial control of a new invasion or a severe infestation, but they are rarely a complete or long-term solution to weed management [11]. See the Weed control methods handbook [102] for considerations on the use of herbicides in natural areas and detailed information on specific chemicals.
Integrated management: Integrated management includes considerations of not only killing the target plant but also of establishing desirable species and maintaining weed-free systems over the long term. Integrated management techniques may be more effective than individual methods at controlling creeping jenny, but as of this writing (2011) no information was available on this topic.Palatability and/or nutritional value: Creeping jenny foliage was consumed by woodland jumping mice near Ithaca, New York [116] and by white-tailed deer in east-central Illinois [69]. According to a fact sheet, rabbits and groundhogs may occasionally eat creeping jenny. Plant secondary compounds apparently make creeping jenny foliage bitter and unpalatable to many mammalian herbivores [36].
Creeping jenny flowers are visited by a variety of invertebrates, particularly bees (see Pollination and breeding system). On the British Isles, aphids (Pemphigidae) feed on the stems and roots of creeping jenny [23].
Cover value: No information is available on this topic.
Plant community associations of nonnative species are often difficult to describe accurately because detailed survey information is lacking, there are gaps in understanding of nonnative species'
ecological characteristics, and nonnative species may still be expanding their North American range. Therefore, creeping jenny may occur in plant communities other than those discussed here and listed in
the Fire Regime Table.
Creeping jenny occurs in a variety of habitats and plant communities throughout the United States that
are similar to those of its native range (see Site Characteristics). It occurs primarily in floodplain forests and woodlands; along riverbanks and shorelines of lakes
and ponds; in wet meadows and mesic grasslands; and in seeps, fens, bogs,
marshes, and swamps. It also occurs in anthropogenically disturbed areas such as cultivated, fallow,
and successional fields, lawns, railroad rights-of-way, roadsides, and ditches
(e.g., [5,29,36,45,55,60,78,85,87,105]).
Riparian floodplain and bottomland forest
communities: In the northern and north-central United States, creeping jenny commonly
occurs in forested swamps and in mixed-hardwood riparian floodplain and bottomland forest communities. Along Little Otter Creek, Vermont, creeping jenny was the 2nd densest forb in a closed-canopy yellow birch-sugar maple-American beech (Betula alleghaniensis-Acer saccharum-Fagus grandifolia) floodplain forest [42]. In the upper Passaic River basin of northern New Jersey, it was the most common nonnative species in pin oak-silver maple (Quercus palustris-Acer saccharinum) floodplain forests [3]. In northwestern Pennsylvania, it was the 4th most common forb in a riparian silver maple-sycamore (Platanus occidentalis) forest community [114].
In south-central Pennsylvania, creeping jenny was one of the most abundant forbs in the pin oak-red maple/gray's sedge-white avens (Acer rubrum/Carex grayi-Geum canadense)
association in bottomland mixed-hardwood forests [74]. Throughout Massachusetts, creeping jenny occurred in the silver maple-green ash (Fraxinus pennsylvanica)-pin oak forest association in small river floodplain forests [44]. It occurred in a mid-successional Freeman maple (Acer rubrum × A. saccharinum) bottomland swamp in western New York [8]. At Delaware Water Gap National Recreation Area, creeping jenny occurred in the black cherry (Prunus serotina)-yellow-poplar (Liriodendron tulipifera)-red maple-white ash (Fraxinus americana) bottomland mixed-hardwood forest association and in the sycamore-green ash floodplain forest association [73]. At Valley Forge National Historical Park in southeastern Pennsylvania, it occurred in the sycamore-green ash association in early-successional riverine floodplain forests [76]. In Evansburg State Park, southeastern Pennsylvania, it occurred in red maple-mixed shrub palustrine woodlands and in sycamore-boxelder (Acer negundo) floodplain forests [46]. In Vermillion County, Illinois, creeping jenny occurred in silver maple floodplain forests and in silver maple/buttonbush (Cephalanthus occidentalis) swamps [52].
In the Southeast, creeping jenny commonly occurs in mixed-hardwood riparian floodplain and bottomland forest communities. On Plummers Island, Maryland, it occurred in a rocky channel in a floodplain dominated by hackberry (Celtis occidentalis), slippery elm (Ulmus rubra), black willow (Salix nigra), eastern cottonwood (Populus deltoides), river birch (Betula nigra), boxelder, and pawpaw (Asimina triloba) [90]. In Stewart County, Tennessee, it occurred in bottomland hardwood forests dominated by boxelder, silver maple, river birch, bitternut hickory (Carya cordiformis), and green ash [13]. Along the New River Gorge National River in West Virginia, creeping jenny occurred in sycamore-river birch forest and black willow-river birch streambeds that were often flooded during high water [97]. In Fairfax County, Virginia, it occurred in the sycamore-silver maple-river birch-green ash/smallspike false nettle-Emory's sedge (Boehmeria cylindrica-Carex emoryi) bedrock floodplain woodland community; the sycamore-river birch-willow (black and coastal plain (Salix caroliniana) willow) woodland community on coarse-textured depositional bars flooded multiple times each year; and the yellow-poplar-red maple-boxelder-sycamore/American hornbeam-jumpseed (Carpinus caroliniana-Polygonum virginianum) small-stream floodplain forest community [93].
Other forest communities: In Evansburg State Park, Pennsylvania, creeping jenny was dominant in the understory of ash (Fraxinus spp.), eastern white pine (Pinus strobus), and Norway spruce (Picea abies) plantation forests and occurred in eastern redcedar (Juniperus virginiana) woodlands [46].
At the Waterloo Wildlife Research Station, Ohio, creeping jenny occurred in 7- to 9-year-old clearcuts dominated by pin oak, red maple, yellow-poplar, and bigtooth aspen (Populus grandidentata)
with an understory of sassafras (Sassafras albidum), common greenbriar
(Smilax rotundifolia), and blackberry (Rubus spp.) [92].
Along the New River Gorge National River, creeping jenny occurred in Virginia pine
(Pinus virginiana)-eastern redcedar-post oak (Quercus stellata) woodland, a xeric community with exposed sandstone bedrock and an open canopy [97].
Wetland and shoreline herbaceous communities: In south-central Pennsylvania, creeping jenny occurred in the bluejoint reedgrass-bullrush-threeway
sedge (Calamagrostis canadensis-Scirpus spp.-Dulichium arundinaceum) association in wet meadows where the soil was saturated and under standing water for at least part of the growing season [74]. In central Pennsylvania, it occurred in the fringed
loosestrife-Indianhemp (Lysimachia ciliata-Apocynum cannabinum) association on
low terraces and gravel bars [75]. Around freshwater springs in southern Illinois, creeping jenny was common in the fowl mannagrass/Indian woodoats (Glyceria striata/Chasmanthium latifolium) community along riverbanks and in a gravelly bar [71]. Along the New River Gorge National River, creeping jenny occurred in fringed sedge (Carex crinita) wetlands and in American eelgrass-pondweed (Vallisneria americana-Potamogeton spp.) wetlands [97]. In Great Falls Park, Virginia, it occurred in the lateflowering thoroughwort (Eupatorium serotinum)-knotweed
(Polgonum spp.) community on sandy bars and on riverbanks [93].
A vegetation classification from Illinois described 2 plant communities in which creeping jenny is a dominant species:
Creeping jenny is insect pollinated [23,55]. Melittid bees pollinate other yellow loosestrife species and possibly pollinate creeping jenny [36]. A fact sheet speculated that creeping jenny often fails to form seed capsules because melittid bees are uncommon in North America (see Seed production) [36]. However, Cane and others [12] noted that Macropis nuda visited native fringed loosestrife but did not visit creeping jenny despite the fact that creeping jenny grew within 10 feet (3 m) of a Macropis nuda nest site. Vogel (1986 cited in [7]) noted that, despite the presence of suitable pollinators in central and northern Europe, insects, including melittid bees, rarely visited creeping jenny flowers. In a pollinator preference study in a common garden experiment in Delaware, nonnative European honey bees (Apis mellifera) tended to visit creeping jenny more often than native fringed loosestrife. Conversely, native pollinators tended to visit fringed loosestrife more often than creeping jenny. The authors reported that the following native invertebrate species visited creeping jenny during 2 summers: carpenter bees and bumble bees (Apidae), sweat bees (Halictidae), butterflies (Lepidoptera), flies (Diptera), wasps (Hymenoptera), and beetles (Coleoptera) [14].
According to fact sheets, creeping jenny flowers infrequently [36,105]. Creeping jenny flowers are hermaphroditic [23,55] and typically self-incompatible [7,26]. In creeping jenny's native range, self-compatability appeared more common in eastern and southeastern European populations than in central and northern European populations [7].
Researchers have reported creeping jenny in seed banks (e.g., [8,23,42]). In a Freeman maple bottomland swamp in western New York where mean creeping jenny cover was 0.2%, and creeping jenny seedlings were the 3rd most dense seedlings observed (x=1.32 seedlings/120 cm²), seedling emergence tests indicated a mean density of 1.01 seeds/120 cm² in the upper 2 inches (5 cm) of soil in April [8]. Along Little Otter Creek, Vermont, seed density was measured in October in flood debris and in the upper 2.6 inches (6.5 cm) of soil at 16, 82, and 164 feet (5, 25, and 50 m) from the creek bank. Five creeping jenny seeds germinated from flood debris collected at 16 and 82 feet, but no creeping jenny seeds germinated from soil samples collected at these distances. Eleven creeping jenny seeds germinated from flood debris and 5 creeping jenny seeds germinated from soil samples collected at 164 feet from the creek bank. creeping jenny density in the standing vegetation increased at greater distances from the creek bank, with no creeping jenny plants present at 16 feet, 11,000 creeping jenny stems/ha at 82 feet, and 47,000 stems/ha at 164 feet from the creek bank [42]. According to a review, studies in northwestern Europe reported creeping jenny seed densities in the seed bank ranging from 48 to 240 seeds/m² [23].
In contrast, other researchers reported that creeping jenny was sparse or absent from the seed bank despite abundance in the standing vegetation (e.g., [53,54,63,112]). Creeping jenny was "abundant" in a wet meadow in northeastern France but no creeping jenny seeds germinated from soil samples taken from the upper 4 inches (10 cm) of soil in April [112]. In a Dutch mixed-hardwood forest, creeping jenny was present in the herb layer, but only 1 creeping jenny seed germinated from 28 soil samples taken from the upper 4 inches of soil in late March and early April [47]. In a foxtail-official burnet (Alopecurus pratensis-Sanguisorba officinalis) flood-meadow community near Oxford, England, creeping jenny occurred in 49% of plots, but no creeping jenny seeds germinated from soil samples taken from the upper 4 inches of soil in November [63].
McDonald and others [63] classified creeping jenny seeds as transient or short-term persistent in the seed bank. Transient seeds were those that were viable in the soil for <1 year and short-term persistent seeds were those that were viable 1 to 5 years. Creeping jenny seed-bank classification was determined via a combination of creeping jenny's presence in the standing vegetation, the absence of creeping jenny seeds in the soil seed bank, and a review of published literature as of 1996 [63].
Seed production by creeping jenny is rare in the United States [36,81] and in its native range [7]. When seeds are produced, they are often inviable [26,36]. Ray [81] found no viable seeds in North American populations of creeping jenny in 1956. Despite low viable seed production in many populations, some researchers reported viable creeping jenny seeds in seed banks (e.g., [8,23,47]).
Seed production may be favored by intermittent flooding and an open canopy. In its native range in East Bohemia, creeping jenny appeared along a shoreline after flooding. After the area was flooded again 3 years later, creeping jenny flowered and produced seeds [49], suggesting that seed production was favored by flooding and that creeping jenny plants were sexually mature when 3 years old. Conversely, in a greenhouse experiment in France, "extreme dryness" favored fruiting and viable seed production in creeping jenny (Gagnepain 1927 cited in [81]). In its native range in Great Britain, creeping jenny spread "almost exclusively by its runners and only produced any appreciable amount of seed in hot summers where the shade was slight" [86].
Creeping jenny is apparently able to establish and survive in communities of varied age and disturbance regimes. It is present in early-seral [72,76,92], mid-seral [8], and late-seral [21,41] habitats. Creeping jenny grows in full sun to full shade.
Shade tolerance: Creeping jenny can grow in sites with full sun, partial shade, or full shade (e.g., [19,97,113]). Some publications reported that creeping jenny prefers shady sites [105,108], whereas others reported that creeping jenny prefers full or partial sun [23,55]. According to a fact sheet, creeping jenny can tolerate the shade of taller grasses and forbs [36], and it commonly occurs in closed-canopy forests (e.g., [15,27,42]). Conversely, limited evidence suggested that tall grasses may shade out creeping jenny [67], and creeping jenny commonly occurs in habitats with an open canopy (e.g., [71,74,75,93,97]). In eastern cottonwood/black willow floodplain forests in Wisconsin, creeping jenny occurred less often in plots with a shrub overstory than in plots without a shrub overstory (P=0.05). The authors concluded that creeping jenny was either a "light specialist" that was inhibited by reduced light under woody understory vegetation or that creeping jenny did not compete well for available water or nutrients with woody plants [2]. Nonetheless, creeping jenny can apparently establish on sites with a wide range of overstory and understory conditions. In pin oak-silver maple floodplain forests in the upper Passaic River basin of northern New Jersey, creeping jenny frequency ranged from 10% to 83% at sites with 100 to 620 trees/ha in the canopy and 20 to 580 stems/ha in the subcanopy [3].
Response to disturbance: Creeping jenny commonly occurs in areas frequently disturbed by flooding (e.g., [2,75,93]). In central Pennsylvania at the Johnstown Flood National Memorial, creeping jenny occurred in the fringed loosestrife-Indian hemp association on low terraces and gravel bars in the flood scour zone of the Little Conemaugh River. This association had abundant bare soil because the river periodically scoured the soil and exposed new substrate [75]. In Wisconsin, creeping jenny occurred in eastern cottonwood/black willow floodplain forests where regular, moderate levels of disturbance occurred annually [2]. In Great Falls Park, Fairfax County, Virginia, creeping jenny occurred in sycamore-river birch-willow woodland on coarse-textured depositional bars that were flooded multiple times each year [93]. In northeastern Virginia, creeping jenny occurred in shrubby, early-successional, "highly disturbed" forests dominated by hackberry, eastern redcedar, and sweetgum (Liquidambar styraciflua) that were fringing rivers, ponds, and marshes [72].
Creeping jenny also occurs in anthropogenically disturbed areas. In Indiana, creeping jenny occurred in a 10-year-old abandoned corn (Zea mays) field dominated by common evening primrose (Oenothera biennis) [41]. In Athens County, Ohio, creeping jenny occurred in 7- to 9-year old clearcuts [92].
Occurrence in mid- to late succession: Creeping jenny is often found in mid- to late-seral communities. According to expert opinion, creeping jenny in Wisconsin had a high probability of being found in sites that had not been disturbed within the past 10 years [83]. In southwestern Illinois, creeping jenny was the only nonnative species present in an old-growth floodplain forest dominated by silver maple, boxelder, shellbark hickory (Carya laciniosa), slippery elm, and bur oak (Quercus macrocarpa) [100]. In the Black Mountains of North Carolina, creeping jenny occurred in the "climax" cove hardwood forest association. The most frequent tree species were American chestnut (Castanea dentata), yellow-poplar, eastern hemlock (Tsuga canadensis), northern red oak (Quercus rubra), and red maple [21]. In the floodplain of the Millstone River, New Jersey, creeping jenny occurred in old fields with apple (Pyrus malus) and hawthorn (Crataegus spp.) that had succeeded to shaded, moist woodlands of slippery elm, American elm (U. americana), shagbark hickory (Carya ovata), swamp white oak, black cherry, American hornbeam, and osage orange (Maclura pomifera). It was also common in "old" white ash-silver maple-pin oak/northern spicebush (Lindera benzoin) floodplain forests [111]. In Allegany County, New York, creeping jenny was recorded in a 70-year-old abandoned farm field dominated by American beech, eastern hophornbeam (Ostrya virginiana) and black cherry during 1 year of the study, but was not observed during the 4 subsequent years. This suggested that creeping jenny established in the old field but did not persist [18].Creeping jenny appears to reproduce primarily vegetatively [45,105,108] and often forms vegetative colonies [2,36]. While some floras indicate that creeping jenny is rhizomatous [25,31,40], most descriptions of creeping jenny indicate that it reproduces by stems that creep along the ground and root at leaf nodes [36,45,105]. According to Taft [100], creeping jenny was not known to set fruit in Illinois, and it apparently reproduced entirely vegetatively. In central and northern Europe, Bittrich and Kadereit [7] observed that creeping jenny was self-incompatible (see Pollination and breeding system) and speculated that most central and northern European populations were probably vegetative clones.
Vegetative regeneration may be important to creeping jenny's spread because it may be able to sprout from stem fragments [20,45,105].
Lysimachia nummularia is a species of flowering plant in the primrose family Primulaceae. Its common names include moneywort, creeping jenny, herb twopence and twopenny grass.[2]
It is a vigorous, prostrate, evergreen perennial growing to 5 cm (2 in) in height and spreading rapidly and indefinitely by stem-rooting. It has rounded leaves arranged in opposite pairs, and cup-shaped yellow flowers 2 cm in diameter, in summer. It is particularly associated with damp or even wet areas, though in cultivation it will tolerate drier conditions.[3] It is hardy, surviving lows of −15 °C (5 °F) (RHS H5).[2]
It is native to Europe, but has been introduced to North America, where it is considered an invasive species in some areas. It aggressively spreads in favorable conditions, such as low wet ground or near ponds. It is moderately difficult to remove by hand pulling. Any tiny piece left behind will regrow.
The Latin specific epithet nummularia means "like a coin",[4] referring to the shape of the leaves; hence the common names, such as "moneywort", which also references coins.
The cultivar 'Aurea' (golden creeping Jenny) It is cultivated as an ornamental plant, for groundcover where the range of its growth can be limited. It is also suitable as a bog garden or aquatic marginal plant.[5] has yellow leaves, and is somewhat less aggressive than the species. It has gained the Royal Horticultural Society's Award of Garden Merit.[6]
The plant contains a number of phenolic acids.[7]
Lysimachia nummularia is a species of flowering plant in the primrose family Primulaceae. Its common names include moneywort, creeping jenny, herb twopence and twopenny grass.
