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Winter Creeper

Euonymus fortunei

Summary 6

Euonymus fortunei (common names spindle or fortune's spindle, winter creeper or wintercreeper) is a species of flowering plant in the family Celastraceae, native to east Asia, including China, Korea, the Philippines and Japan. It is named after the plant explorer Robert Fortune.

Ecological threat in the united states 7

Traits that make climbing euonymus a desirable ornamental plant, such as its rapid growth, evergreen nature and tolerance of harsh conditions, also make euonymus a threat to natural areas. Climbing euonymus can outcompete native vegetation by depleting soil moisture and nutrients, blocking sunlight, and by forming a dense vegetative mat that impedes the growth of seedlings of native species. Vines on trees continue climbing and can eventually overtop them, covering the leaves and preventing photosynthesis.

Distribution 8

More info for the terms: cover, fern, frequency

Wintercreeper is native to China ([76], reviews by [1,62,73]) and was introduced to North America as an ornamental ground cover in 1907 (reviews by [1,29,52,54]). It has escaped cultivation and established in scattered areas in the central and eastern United States (reviews by [1,52,54]). According to distribution maps provided by Plants Database, in Canada wintercreeper occurs only in Ontario, and in the United States it occurs from Maryland to Wisconsin, south to Georgia and Mississippi (with the exception of West Virginia), and west to Missouri and Nebraska. The distribution of E. f. var radicans is identical to that of the species; while E. f. var fortunei occurs only in Maryland and Illinois [69]. Wintercreeper, along with several other horticultural plant species, is susceptible to attack by a fungal parasite that is native to and occurs only in the southwestern United States and adjacent Mexico (Duffield and Jones 1998 as cited by [40]). This fungus, Texas root rot (Phymatotrichum omnivorum), may exert a strong influence on plant invasions in that region [40].

Local floras and other references report varying frequency of escape from cultivation among areas where wintercreeper occurs, suggesting a scattered and disjunct pattern of distribution. Wintercreeper occasionally escapes in the northeastern United States [22,42]. It was observed and described as "naturalized" along the west bank of Rock Run near Plummers Island in Maryland around 2003 [56]. It appeared "sporadically" as escapes in Ohio as of 1961 [3] and "seldom" escaped in Michigan as of 1985 [73]. It was a newly reported component of the flora in Illinois sometime between 1956 and 1978 [27], listed in only 1 county there in 1978 [47], and described as "infrequently escaped from cultivation and scattered" in 1986 [46]. A 1990 review by Hutchison [29] reports that wintercreeper occurred mostly near urban centers in Illinois, with reports from several sites in the East St Louis area. It was common throughout Giant City State Park and Fern Rocks Nature Preserve in Jackson County, Illinois, and near Karnak in Pulaski County [29]. Wintercreeper was not described the flora of the Carolinas (1968), but the flora states that various horticultural species of Euonymus (including wintercreeper) "may persist around old homesites or may rarely escape from cultivation" [50].

Forest Inventory and Analysis (FIA) data from forests in 12 southern states indicate that wintercreeper was detected in only 5 states and was most common in Kentucky and Tennessee [44]: Estimated acres covered by wintercreeper in forests in the southern United States, summed from subplots within each state using the Southern Research Station's Forest Inventory and Analysis database from 15 March 2008 [44] AL AR FL GA KY LA MS NC SC TN TX VA 0 82 0 0 6,644 0 0 164 0 4,328 0 7

Impacts and control 9

More info for the terms: fern, fire management, invasive species, liana, mesic, natural, nonnative species, root collar, swale, swamp, top-kill, tree, vines

Impacts: As of this writing (2009), no studies were found in the available literature on the impacts of wintercreeper invasion; however, several reviews [12,29,35,52,54,62,64,67] and personal communications [9,38,63] indicate that wintercreeper is persistent,competitive, and difficult to control in some areas. A review by Remaley [52] suggests that the traits that make it a desirable ornamental plant, such as rapid growth, evergreen nature, and tolerance of variable site conditions, also make it a threat to natural areas. Reviews suggest that wintercreeper outcompetes and displaces native groundlayer plants (e.g., [12,52,62]) and may form single-species stands (review by [54]). Decreased native plant diversity may negatively impact native fauna (e.g., butterflies) [54]. Based on observations in Illinois, Hutchison [29] states that wintercreeper is a serious potential threat because it spreads rapidly and replaces spring ephemerals. In mesic and dry-mesic woods at Fern Rocks Nature Preserve, wintercreeper covered the ground and eliminated native groundcover species in many places [29]. Reviews suggest that wintercreeper may overtop and block sunlight to trees [12,52], possibly smothering and killing them [54], especially smaller trees (up to about 20 feet (6 m) tall) (personal communication [63]). Wintercreeper liana in an ice-felled black cherry (Prunus serotina), approximately 40 feet (12 m) from the root collar. Photos, courtesy of David Taylor, taken 6 March 2009.

Rankings by the USDA, Forest Service [66,67], local exotic pest plant councils [21,35,45,57,64], and the Virginia Department of Conservation and Recreation [72] suggest that as of 2009, wintercreeper may be most invasive and have the greatest impact in the Southern Region, especially in Kentucky, Tennessee, and Missouri: Invasiveness rankings by state and region in order of threat level Area Rank Rank definition States Kentucky Severe threat Nonnative plant species that possess characteristics of invasive species and spread easily into native plant communities and displace native vegetation. Includes species which are or could become widespread in Kentucky [35] Tennessee Rank 1, severe threat Nonnative plant species that possess characteristics of invasive species and spread easily into native plant communities and displace native vegetation [64]. Missouri Category A-2 Plant species that are invading and disrupting native plant communities in more than 10 counties in Missouri  [45] Virginia Moderately invasive Nonnative plants that may have minor influence on ecosystem processes, alter plant community composition, and affect community structure in at least one layer. They may become dominant in the understory layer without threatening all species found in the community. Usually require a minor disturbance to establish [72] South Carolina Watch A Nonnative plants found in South Carolina in limited infestations that are a potential threat to natural areas. They exhibit invasive characteristics such as high reproductive rate, high growth rate, and independent establishment of new populations [57]. Georgia Category 3 Plants that are a minor problem in Georgia, or not yet known to be a problem in Georgia, but known to be a problem in adjacent states [21]. Regions Forest Service, Southern Region Category 1 Nonnative plant species that are prohibited and must be controlled. These species are known to be invasive and persistent throughout all or most of their range within the Southern Region. They can spread into and persist in native plant communities and displace native plant species and therefore pose a demonstrable threat to the integrity of the natural plant communities in the region. Their use is prohibited on National Forest lands. Efforts to control these species are encouraged [67]. Forest Service, Eastern Region Category 2 These plants are less invasive than those in Category 1. If these species are significantly replacing native species, they are doing so only in local areas [66].

Control: Probably the most effective way to control wintercreeper is to prevent its establishment by minimizing its use as a landscape plant and preventing further seed dispersal (see Prevention). Once established, control of wintercreeper requires complete removal of plants and roots, because it can spread vegetatively (see Vegetative regeneration). According to Hutchison [30], the most effective management of wintercreeper is to totally eradicate it from natural areas and the surrounding vicinity by pulling and removing individuals as soon as possible after recognition.

Fire: For information on the use of prescribed fire to control this species see Fire Management Considerations.

Prevention: 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 [41,55] and by conducting monitoring several times each year [31]. Managing to maintain the integrity of the native plant community and to mitigate the factors enhancing ecosystem invasibility is likely to be more effective than managing solely to control the invader [28].

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 [68]. See the Guide to noxious weed prevention practices for specific guidelines in preventing the spread of weed seeds and propagules under different management conditions.

The simplest way to prevent wintercreeper establishment is to not plant it. Wintercreeper is commonly sold as a groundcover for landscaping [12]. Native creeping or climbing vines that may make good alternatives to wintercreeper in the eastern United States include trumpet creeper (Campsis radicans), Dutchman's pipe (Aristolochia macrophylla), crossvine (Bignonia capreolata), trumpet honeysuckle (Lonicera sempervirens), American bittersweet (Celastrus scandens), and American wisteria (Wisteria frutescens) [52,62]. If bittersweet and wisteria are used, make sure they are native species, as nonnative species in these genera (C. orbiculatus, W. floribunda, and W. sinensis) are also invasive.

Prevention of fruiting is critical to prevent further spread of wintercreeper once it is established. This is accomplished by cutting climbing stems to prevent flowering and fruiting (see Flowering and seed production), and repeating cutting to keep stems from climbing again (personal communication [63]).

Cultural control: According to Hutchison [29], no native species are known that can compete with wintercreeper in Illinois. However, planting competitive, desirable native species may help suppress wintercreeper as part of an integrated management plan (personal communication [38]).

Physical or mechanical control: Hand-pulling or grubbing using a pulaski or similar digging tool may control small populations of wintercreeper (reviews by [1,52]). In order to be effective, the entire plant, including the roots, stem fragments, and fruits, must be bagged and removed from the site to prevent reestablishment. Any portion of the remaining root system may sprout (reviews by [1,30,52,54]). Young plants with small root systems are likely easiest to control in this manner. Hand-pulling is easiest when soils are moist (reviews by [1,52]). Hand-pulling may be impractical for large infestations (review by [29]).

Cutting is not recommended as a control method except to prevent fruiting (personal communication [63], reviews by [43,54]) or in combination with herbicide application (see Chemical control). Cutting alone may lead to sprouting from roots, root crowns, and cut stems (personal communications [38,63], review by [52]). Mowing is similarly ineffective without chemical treatment and not practical in natural areas (review by [29]).

In an area of Kentucky where wintercreeper grew in monoculture (no native plants were visible), it was effectively suppressed when light was excluded by covering the population with 6 mil black plastic for an entire growing season (personal communication [38]); however, wintercreeper may require 2 years of covering to die (personal communication [9]).

Biological control: Biological control of invasive species has a long history that indicates many factors must be considered before using biological controls. Refer to these sources: [71,75] and the Weed control methods handbook [65] for background information and important considerations for developing and implementing biological control programs.

As of this writing (2009), no effective biological controls were known for wintercreeper. However, wintercreeper is one of the top 10 invasive plants of Asian origin in the United States that is being studied for future biological control opportunities, and scientists are looking for host-specific natural enemies in China [16]. Dirr [17] lists several diseases and insects that impact wintercreeper in North America. It is especially susceptible to damage and mortality from the Asian euonymus scale (Unaspis euonymi), which is not native to but does occur in North America [70]. The euonymus scale has been lethal to wintercreeper on many plantings, especially those containing the cultivars 'Vegetus', 'Coloratus', and Euonymus tree species such as European spindletree (E. europaeus), winterberry euonymus (E. bungeanus), and Hamilton's spindletree (E. hamiltonianus subsp. sieboldianus) (review by [17]). This same scale is also showing up on native Euonymus species, burningbush (E. atropurpurea) and bursting-heart (E. americanus), and it is causing mortality in populations of Canby's mountain-lover (Paxistima canbyi), a rare subshrub, in Kentucky (personal communication [63]). At least 5 organisms (2 insect predators and 3 aphelinid parasitoids) have been collected in Asia and released in southern New England as biological control agents against the euonymus scale. Releases were made in Massachusetts, Connecticut, and Rhode Island on wintercreeper and European spindletree plants infested with medium to large populations of euonymus scale in urban and suburban locations from 1991 to 1995 [70].

Intense seasonal browsing with domestic goats and/or sheep is being investigated as a potential control for wintercreeper in Kentucky. This approach shows some promise because wintercreeper is reportedly a frequent favorite for most livestock under the right conditions, and it is much browsed by white-tailed deer in the winter (personal communication [9]).

Chemical control: On wintercreeper populations that are too large to control by hand-pulling or digging, foliar or cut-stem applications of herbicides may be effective (reviews by [1,12,30,52,54]). Cut stem application of herbicides is effective in areas where lianas are well established on or around nontarget plants or where they have grown into tree canopies or other vertical surfaces. Subsequent foliar application of herbicides will likely be required for adequate control [1,52]. Foliar applications of herbicide may be used to control large populations of wintercreeper. It may be necessary to precede foliar sprays with cut stem treatments to reduce the risk of damage to nontarget plants [1,52]. Whichever method is used, multiple herbicide treatments are needed to control wintercreeper (personal communications [38,63]) because it sprouts following top-kill.

Recommended timing of herbicide treatment for wintercreeper is late fall, when most native vegetation is dormant, or in spring prior to emergence of spring ephemerals (reviews by [12,30]). Herbicide use is not recommended during the growing season, when native species are likely to be impacted. Care should be taken to avoid contacting nontarget species with herbicide (review by [30]).

Herbicides may be 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 [8]. See the Weed control methods handbook [65] for considerations on the use of herbicides in natural areas and detailed information on specific chemicals. See these sources: [1,43,52] for details on specific chemicals, timing, rates, and methods used for controlling wintercreeper. Integrated management: Intensive management of wintercreeper monocultures, integrating burning with a propane torch and/or spot spraying with glyphosate followed by planting of desirable species, may effectively suppress wintercreeper and promote desirable plant communities. Monocultures in Kentucky were sprayed with glyphosate in spring, when there were about 6 newly-formed leaves without a thick cuticle. Leaves turned red and dropped off in the fall. Any new wintercreeper sprouts that emerged the following spring were spot sprayed with glyphosate, and where the native seed bank was slow to respond, wild rye (Elymus villosus and E. macgregori) was seeded. Areas with dense wild rye stands had no rebound of wintercreeper populations (personal communication [38]). An intensively managed swale that was once 100% wintercreeper. Treatments were: burning with propane torch, followed by spot spraying of glyphosate and hand pulling of sprouts the 1st year; and planting swamp milkweed (Asclepias incarnata), wild rye and fowl manna grass (Glyceria striata) plugs the 2nd year. Photo taken in year 3 (personal communication [38]).
Photo courtesy of Jim Lempke, University of Kentucky Arboretum

Habitat in the united states 10

Climbing euonymus tolerates a variety of environmental conditions, including poor soils, full sun to dense shade, and a wide pH range. It does not do well in heavy wet soils. Natural forest openings resulting from wind throw, insect defoliation or fire are vulnerable to invasion and provide conditions for satellite populations of climbing euonymus to get started.

Habitat characteristics 11

More info for the terms: association, cover, mesic, natural

Much of the information regarding site tolerances of wintercreeper comes from reviews [1,12,17,30,52,54,62] in which the source of the original information is not given or not clear, and it appears that they mostly cite one another. Very little primary information from field observations was found in the available literature as of 2009. No information was found describing invasive populations: on sites where wintercreeper occurred it was typically described as occasional or rare. Thus the following description does not necessarily describe sites where wintercreeper is most likely to be invasive.

Disturbance: As a popular ornamental plant, wintercreeper is usually associated with human habitation and disturbance. Wintercreeper was scarce and occurred only in disturbed areas including park facilities, clearings, and old homesteads at Fall Creek Falls State Park in Tennessee [19]. It occurred in an urban woodland surveyed in 1987 at the Wave Hill Natural Area in Bronx, New York [77], and in disturbed woodlots in Indianapolis that had evidence of extensive human impact and supported several other nonnative and invasive plant species [53]. One of two collections of wintercreeper in Michigan was from a gravel pit on dumped roadside debris in Benzie County, in 1982 [73]. From home sites where it was planted, wintercreeper sometimes escapes cultivation and establishes, persists, and spreads in surrounding forests, woodlands [1,29,30], riparian communities [1,26,39], and other natural areas (see Habitat Types and Plant Communities). In central Kentucky, wintercreeper is most abundant in older neighborhoods and along country roads, where it frequently covers the trunk and lower third of the crown of old roadside trees (personal communication [63]).

Landforms and climate: As of 2009, no information describing landform preferences or climate tolerances was found in the available literature. According to Schwegman [54] wintercreeper has spread into forests and rocky bluffs in the eastern and central parts of the United States from Chicago southward, although it also occurs in Michigan [73]. Detrended correspondence analysis suggests an association of wintercreeper with floodplains in the eastern United States [39]. Wintercreeper is listed as occurring in coastal plain habitats on hydric and mesic sites in Virginia [72]. In a field study of old-growth forests in central Indiana, wintercreeper occurred on 2 of 14 edges surveyed and was somewhat more common on warm (south- or west-facing) edges than on cool (north or east-facing) edges [7]. Wintercreeper is occasional in deciduous forest and edge habitat in Rock Creek Park in Washington, DC, where the climate is continental, with warm, humid summers and mild to cold winters. The lowest average monthly temperature is 43.5 °F (6.4 °C) in January, and the highest average monthly temperature is 88.2 °F (31.2 °C) in July [20]. Dirr [17] indicates that wintercreeper can grow in USDA Hardiness Zone 4, where the average minimum temperature reaches -30 to -20 °F (-34 to -29 °C), but it is not "happy" there unless provided snow cover or winter shade. It better fits USDA Hardiness Zone 5 (average annual minimum teperature of -20 to -10 °F (-29 to -23 °C)) to Zone 8 or 9 (average annual minimum teperature of 20 to 30 °F (-7 to -1 °C)) [17].

No information on wintercreeper's elevational range in North America was found in the available literature as of 2009. In its native China, wintercreeper occurs from near sea level to 11,155 feet (3,400 m) [76].

Soils: According to reviews, wintercreeper is a popular landscape plant due to its rapid growth [1,17] and its ability to tolerate a variety of environmental conditions including heavy shade [1,12,17,30,52], poor soils, and variable pH [1,12,17,52,62]; it apparently does not do well in extremely wet conditions [12,17,30,52]. At Stones River National Battlefield, wintercreeper occurs on flat to gently sloping, rocky upland woods on soils derived from limestones or other basic substrates [49]. In Rock Creek Park in Washington, DC, wintercreeper occurs on low-fertility, fine-textured soils with pH ranging from 3.6 to 5.5 [20]. Wintercreeper occurred on sandy beach berms on the Potomac River lowland that were "occasionally overwhelmed by high tide" [59].

Sources and Credits

  1. (c) anneheathen, some rights reserved (CC BY-NC-ND), https://www.flickr.com/photos/annethelibrarian/5554386416/
  2. (c) NatureServe, some rights reserved (CC BY), https://www.flickr.com/photos/natureserve/16186260123/
  3. (c) Anne McCormack, some rights reserved (CC BY-NC), https://www.flickr.com/photos/mccormacka/5858501056/
  4. (c) Klasse im Garten, some rights reserved (CC BY-NC-ND), https://www.flickr.com/photos/klasseimgarten/1350075918/
  5. (c) Leonora Enking, some rights reserved (CC BY-SA), https://www.flickr.com/photos/33037982@N04/4532854770/
  6. Adapted by Kate Wagner from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Euonymus_fortunei
  7. (c) Unknown, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/22948617
  8. Public Domain, http://eol.org/data_objects/24636020
  9. Public Domain, http://eol.org/data_objects/24636030
  10. (c) Unknown, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/22948619
  11. Public Domain, http://eol.org/data_objects/24636025

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