The red berries and young shoots, as in the previous species are said to be medicinal (Dymock, Pharm. Ind. Reprint ed. 2:301. 1972).
This description provides characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (e.g., [60,64,78,112,122,181].
Above ground: Climbing nightshade is a perennial, rhizomatous [60,64,78,101,131] vine or scrambling shrub. Its base is woody, and the aboveground branches are herbaceous and die back each year. Aboveground stems are typically about 10 feet (~3 m) long [60,78,174], sometimes growing as long as 23 feet (~7 m) (review by [53]). Climbing nightshade's stems can twine over other plants, trail along the ground, or grow erect (reviews by [126,164]). Its leaves vary from about 2 to almost 5 inches (5-12 cm) long. Its inflorescence is a drooping cyme [64,112,174] or panicle [64,134], typically having 7 or more flowers, sometimes as many as 30 [60,64,134]. Its fruit is a berry, 2 to 8 mm in diameter ([64,112,174], reviews by [66,182]). Climbing nightshade seeds are 2 to 3 mm x 1.7 to 2.5 mm and are strongly flattened (reviews by [66,164,183]).
Below ground: Climbing nightshade spreads by rhizomes [60,64,78,101,131]. The main root grows horizontally just below the soil surface, sprouts frequently (review by [53]), and can branch 3 to 5 times [18]. Roots of climbing nightshade have secondary growth and an epidermis that is protected by a layer of suberin at the root cap. Feeder roots are 100 to 500 µ in diameter and sprout root hairs that grow up to 400 µ [18].
Brundrett and Kendrick [18] determined that the roots of climbing nightshade can be colonized by mycorrhizal fungi, albeit poorly, and classified climbing nightshade as facultatively mycorrhizal. Species classified as facultatively mycorrhizal may benefit from a mycorrhizal association but are not dependent on it (Janos 1980, cited in [18]).
Population structure: Plants grow singly or in dense patches, often taking advantage of structural support (i.e., trees, shrubs, fences) to reach more light (reviews by [93,164]). Climbing nightshade may be a dominant species on some sites ([22,46,137,166], review by [125]), form small, near monocultures (review by [125]), or be locally abundant (review by [126]) in riparian areas and other moist habitats, especially in New England [22,166], the mid-Atlantic states (review by [126]), the Great Lakes states (reviews by [125,126]), and the Pacific Northwest ([46,47], reviews by [125,137,166]).
Allelopathy: Water extract from the foliage of bittersweet nightshade significantly inhibited some aspects of growth in red pine (Pinus resinosa) seedlings, suggesting allelopathic properties. Red pine seedlings treated with the extract exhibited a decrease in the production of secondary needle fascicles and a significant decrease in shoot weight (P<0.05) and radicle elongation (P<0.001) [128]. As of this writing (2009), however, allelopathy in climbing nightshade has not been studied in the field.
Climbing nightshade is a nonnative species in North America that has been introduced throughout many parts of Canada and the United States. According to Plants Database, it occurs in all conterminous states except Arizona, Texas, Arkansas, Louisiana, Mississippi, Alabama, and South Carolina [163]. A single specimen was observed at a residence in Arizona in 1989 [145]. In Canada, climbing nightshade occurs in all provinces except Alberta and Manitoba and has not been reported in the northern territories [163]; its northern limit in North America was reported to be near 46°N [152]. In the United States, climbing nightshade is reported to be most common in the eastern and north-central United States (review by [164]), and widespread in the upper Great Lakes states (review by [28]) and the Pacific Northwest (reviews by [93,125,126]). Plants Database provides a distributional map of climbing nightshade and its varieties in the United States and Canada.
Climbing nightshade is native to Europe from central Norway, south to northern Africa, and east and central Asia ([57,74], reviews by [53,183]). As a result of its introduced range, climbing nightshade is considered to have a circumpolar distribution [84]. Climbing nightshade has also been introduced to Peru [13], New Zealand, and Australia ([87], review by [126]).
Probable causes of climbing nightshade introduction to North America are cultivation by early settlers (reviews by [53,117,183]) and agricultural and shipping activities in the Pacific Northwest [51,52]. The earliest reports of climbing nightshade's establishment outside of cultivation in North America are from the Great Lakes region, where it occurred by the mid-1800s ([169], Wisconsin State Herbarium 2006 as cited in [126]). Floras and surveys indicate that climbing nightshade spread to parts of the eastern and western United States by the early 1900s [73,109,144,175].
Potential for postfire establishment and spread: As of this writing (2009), climbing nightshade had not been studied from a fire management perspective. Fire may hinder its ability to regenerate vegetatively, but its ability to establish on open, disturbed sites (see Successional status) from off-site seed sources suggests that fire could create favorable conditions for climbing nightshade establishment. However, frugivorous birds typically prefer woody vegetation for perching [98,150], so for sites where trees and other woody vegetation have been severely damaged by fire, mammals may be the main vector for climbing nightshade seed dispersal [96].
Use of prescribed fire as a control agent: Information pertaining to the use of fire as a control for climbing nightshade is limited. One study suggested that increased fire frequency might help to control nonnative species on a site where climbing nightshade occurred [12]. Thirty years of fire exclusion in a remnant oak savanna in Illinois had altered community structure from an open-canopy savanna with few canopy trees, toward a closed-canopy forest with few gaps. Climbing nightshade occurred in the savanna, primarily under canopy trees (see Successional status), and was one of a few dominant nonnative species on this site. Based on the negative relationship observed between increases in light and nonnative species richness, the authors suggested that restoring light levels to the site by increasing fire frequency may reduce nonnative species richness on this site. The authors cautioned, however, that prescribed fire alone may not permanently reduce nonnative species because some may sprout after fire or respond favorably to increased light; subsequent herbicide applications may be necessary (see Impacts and control). The authors also indicated that more information on the ground-layer vegetation and its response to light gradients was needed before prescribed fire could be considered as a management option in the savanna [12].
Another study from east-central Minnesota used prescribed fire over a 20-year period in an attempt to restore oak savanna on a site that had transitioned to oak forest as a result of fire exclusion [160]. Fire was reintroduced to 9 sites at varying return intervals ranging from about once a year to once every 10 years. Climbing nightshade was one of 113 plant species that occurred in the study area 20 years after prescribed fire was introduced, suggesting fire may not prevent its occurrence. However, information pertaining to its prefire occurrence and its postfire abundance is lacking, making it difficult to determine its relationship to fire. Additionally, it is unclear if climbing nightshade occurred on sites burned frequently, on sites burned every 10 years, or in unburned sites used as a control [160], making it difficult to infer how fire-return interval might influence its populations.
Fire suppression and disturbance: Fire prevention and suppression techniques often disturb soil and vegetation on unburned sites and could provide opportunity for climbing nightshade establishment. In California, a small amount of climbing nightshade established in one plot (n>1000) on areas cleared for a fuel break [118].
For general recommendations on preventing establishment and spread of invasive plants during fire suppression activities or after wild or prescribed fire, see the following publications: [6,15,62,162].
Bittersweet nightshade's shade tolerance and preference for moist habitats suggest that it may persist in habitats associated with long fire-return intervals. Available literature suggests that in North America, climbing nightshade is most common in riparian areas in the eastern, Great Lakes, mid-Atlantic and northwest regions of the United States (see Habitat types and plant communities). Few studies have investigated the behavior, properties, and influence of wildfire in riparian areas. However, riparian forests generally have more available moisture and may differ in understory vegetation, fuel loads, and fuel moisture from adjacent uplands. In these communities, fire typically has longer return intervals and is less severe than in adjacent uplands, especially in the moist forest types [36] where climbing nightshade typically occurs.
Climbing nightshade is commonly found in moist deciduous forests in the eastern, mid-Atlantic, and Great Lakes regions of the United States. Although stand-replacing disturbances are more often caused by other natural events (e.g., hurricanes, ice storms) than fire in these areas, fire has likely played a role in shaping the structure and composition of the vegetation [185]. Deciduous forests in these regions typically have long fire-return intervals, estimated at several hundred to greater than 1,000 years for mixed-severity or stand-replacement fires and somewhat more frequent for low-severity or surface fires (see the Fire Regime Table).
Although climbing nightshade often occurs in vegetation communities associated with relatively long fire-return intervals, it can occur in communities characterized by frequent fire-return intervals, such as oak savanna. Return intervals for stand-replacement fires in oak savannas in the Great Lakes region range from about 50 to 500 years, and return-intervals for surface or low-severity fires range from about 1 to 20 years with an average return interval of 5 years (see the Fire Regime Table).
Climbing nightshade occurs in various types of wetlands, most commonly marshes. Fire is important to the maintenance and development of some wetland communities [56,132,173], and fire-return intervals may be relatively short for marshes. FIRE REGIMES for marshes in the Northeast, Southeast, and Northwest may be characterized by high-severity, stand-replacement fires at intervals of 10 years or less (Fire Regime Table).
The Fire Regime Table summarizes characteristics of fire regimes for vegetation communities in which climbing nightshade 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".
Although climbing nightshade has not been studied for its potential to alter FIRE REGIMES, it is conceivable that climbing nightshade could alter fuel characteristics and impact FIRE REGIMES especially in riparian areas where it forms near-monocultures.
As of this writing (2009), information pertaining to climbing nightshade's fuel characteristics is limited. In the laboratory, climbing nightshade was one of numerous native and nonnative species collected from eastern and mid-Atlantic states that were tested for their combustibility in a cone calorimeter. Based on mean average effective heat of combustion (AEHOC) and mean total heat released (THR), climbing nightshade was slightly less combustible than other species tested and did not have any notable combustion characteristics with one exception: peak heat release rate (PHRR) in climbing nightshade appeared to increase with the thickness of the material being burned, suggesting that dense patches of bittersweet nightshade might combust more rapidly than small patches or individual plants.
A comparison of combustion properties of select noninvasive and invasive species from eastern and mid-Atlantic states with that of climbing nightshade [31] Average effective heat of combustion (MJ/kg) Mean total heat released (MJ/kg) Noninvasive species overall 13.49 12.2 Invasive species overall 13.01 11.72 Climbing nightshade 12.29 10.57The authors speculated that climbing vines like climbing nightshade could potentially alter fire behavior by forming ladder fuels [31]. Annual stem growth that dies back each year contributes to the fuel load, and on sites where climbing nightshade is abundant or has formed near-monocultures (see Population structure), this contribution may be substantial.
General Climate: Climbing nightshade occurs in areas with a mean July temperature of about 72 °F (22 °C) [3,23,85], but it and can also establish in areas with warmer subtropical climates like Florida [181] that experience average July temperatures around 81°F (27 °C) [179]. Climbing nightshade tolerates dormant-season temperatures below freezing ([3,23,85], review by [53]). It commonly occurs in regions of North America that receive moderate annual precipitation from about 32 to 45 inches (810-1,140 mm) [34,85] but also occurs in subtropical climates and in maritime-influenced regions of the Pacific Northwest, where annual precipitation is greater [179]. Climbing nightshade also occurs in semi-arid climates of the Pacific Northwest [23,137], where annual precipitation can be as low as 9.6 inches (244 mm) [23].
Habitat and moisture: Bittersweet nightshade commonly occurs in habitats associated with water, such as riparian areas [23,32,46,71,79,113,121], marshes [30,89,112,122,148,169], wetlands [4,41,63,67,83,123,166], lake shores ([112], review by [53]), forested freshwater dune barriers [10], pond edges [45,169], and canal banks [174]. Climbing nightshade also occurs in moist thickets [64,78,122,169,178], mesic deciduous woods [45,85,99,169], and clearings [60,78,91,169]. In eastern and Great Lakes states, sparse amounts of climbing nightshade occasionally occur in open habitats such as remnant prairie and grasslands [7,167], moist savanna [12,122], and mesic tussock meadow [26].
Climbing nightshade appears to be most abundant in riparian habitats. In western New York, climbing nightshade was a subdominant species in swampy woodland and its edges [166]. Along the Snake River in Idaho, climbing nightshade was present in 60% of sampled sites (n=40) [32]. Climbing nightshade occurred in 82% of the 28 black cottonwood (Populus balsamifera var. trichocarpa)-dominated riparian forests sampled along the Willamette River in Oregon [46]. In western Montana, climbing nightshade was one of the most abundant plants (0.1-2.0% average cover) observed along a portion of Rattlesnake Creek that had been invaded by Norway maple. It was more abundant on sites where Norway maple cover was relatively low and species diversity was greater [137].
Available literature from North America indicates that climbing nightshade can tolerate some flooding and sites inundated with water [3,45,63,71]. The national wetland indicator status for climbing nightshade in most regions where it occurs in the United States is "Facultative", indicating that it has an estimated 34% to 66% probability of occurring in a wetland, and is just as likely to occur in a wetland as a non-wetland. In north-central states such as North Dakota, South Dakota, and eastern Montana, climbing nightshade usually occurs in non-wetland sites and only has a 1% to 33% chance of occurring in a wetland [163]. In Pennsylvania, climbing nightshade occurred in 2.1% of plots that were infrequently flooded but did not occur in plots with frequent to moderate flooding [71]. In another study in Pennsylvania, climbing nightshade was strongly associated with the presence of seasonal surface water in relatively undisturbed wetlands [63]. Climbing nightshade occurred in and near a series of ponds located in 2 lowland deciduous forest woodlots in Ontario, Canada. It commonly occurred in continually flooded areas and the surrounding forest and was considered to be a wet-mesic species in temporarily flooded areas [45]. In Massachusetts, climbing nightshade was found growing in over 1.5 feet (0.5 m) of standing water in a shrub swamp associated with a small stream [3]. One floristic survey from Fire Island Seashore National Park in New York described bittersweet nightshade as favoring dry disturbed sites [34], suggesting that climbing nightshade may also tolerate dry conditions.
In its native range, climbing nightshade is associated with a wide range of habitats [14,57]; however, it maintains a strong affiliation with wet and waterlogged habitats such as seashores, river banks, floodplains, swamps, canals, ditches, mires, damp woods ([43,131], review by [55]), and marshes [14,57,58]. In Europe it is considered a species characteristic of alder fens that occupy "extremely wet ground" where most deciduous woodland plants cannot survive [43], and it is an indicator species of moist to waterlogged habitats that may be inundated throughout the year ([43], Ellenberg 1979 as cited in [131]). It occurs in coastal dunes [9,57], thickets, forest edges, forest clearings, hedgerows, and "waste ground" [131]. It can also occur on dry sites within portions of its native range [58,86]. In central Germany, climbing nightshade occurred on open, fully exposed locations in low-growing, xerophytic shrublands [58]. A small amount of climbing nightshade was also found growing on a sparsely vegetated magnesium limestone cliff face in Sheffield, England [86].
Disturbance: In North America, climbing nightshade appears to prefer sites where the natural vegetation has been altered, such as human developments, roadsides, fence rows, gardens, airstrips, and around buildings [7,34,91,112,130,134,155,167,169,174,181]. Undeveloped sites are also susceptible to invasion by climbing nightshade, but its occurrence on these sites is typically associated with disturbance ([130], reviews by [28,117,126]). In southern Manitoba, climbing nightshade was considered an indicator of disturbance (e.g., social trails, garbage) in an urban riparian forest along the Assiniboine River [120,121]. Its occurrence in wetlands is often associated with some type of disturbance or water level change such as a dike [77], an abandoned limestone quarry [4], or an abandoned municipal dump [140]. Ongoing or previous grazing has also been associated with climbing nightshade occurrence [23,32,105].
Climbing nightshade may occasionally establish in undeveloped, relatively undisturbed native plant communities ([35,130,136,157], reviews by [28,93,126]). A review by NatureServe [126] suggests that riparian areas, wetlands, deciduous forests, and grasslands may be at risk from invasion by climbing nightshade. Invasive plant surveys from Wisconsin indicated that, although climbing nightshade may be more commonly associated with disturbance, it occasionally occurs in wetlands, forests, and grasslands on sites where the ground has not been recently disturbed [136]. Field observation in Illinois occassionally found climbing nightshade in native plant communities with relatively little disturbance [157]. In Washington, climbing nightshade can occur in relatively undisturbed riparian areas and wetlands (review by [93]). An analysis by Parks and others [130] indicated that most vegetation cover types common to the mountain ecoregions of the northwestern United States are susceptible to invasion by bittersweet nightshade when the vegetation is disturbed, but climbing nightshade may invade riparian areas in the absence of disturbance.
Elevation: Information pertaining to bittersweet nightshade's elevational range is patchy. Information from a few regional floras and publications suggests it occurs in a wide range of elevations, from near sea-level along the coasts to over 7,000 feet (2,134 m) in the western United States ([7,16,71,85,91,130,145,174], review by [133]). Available information suggests that climbing nightshade occurs at higher elevations in its native range [2,74,84,180].Substrate: Climbing nightshade occurs in a variety of soil types and textures [26,27,30,41,45,105,121,137,150]. Climbing nightshade commonly occurred on Penobscot Bay in Maine, in shallow soils consisting mostly of humus [22]. In New Jersey, climbing nightshade was more likely to occur on sites with higher percentages of sand [41]. In Montana, climbing nightshade commonly occurred in a riparian deciduous forest characterized by deep, well drained, gravelly loam (Anonymous 1995, cited in [137]). A review [55] indicated that in Europe, climbing nightshade occurs in rich loam and clay.
Climbing nightshade occurs on sites with a range of soil pH. Studies from Illinois [4], Wisconsin [26], Manitoba [121], and Idaho [32] report the occurrence of climbing nightshade on soils with pH ranging from 7.2 to 8.29. In a riparian area along the Snake River in Idaho, climbing nightshade was a dominant species and was most common near seeps with average pH of 8.27 [32]. Additional information suggests that climbing nightshade can tolerate lower pH. In New York [83] and Ontario [30,45], climbing nightshade occurred on sites with soil pH ranging from 5.2 to 7.2. A review grouped climbing nightshade with plants considered "alka-tolerant". Species in this group required pH ranges above 4.8 to 5.2 and were tolerant of pH levels as high as 7.9 to 9 [149].
Climbing nightshade may prefer soils rich in nitrogen. On the Snake River in Idaho, bittersweet nightshade was most dominant on sites associated with relatively high average nitrate levels (39.54 ± 8.32 ppm) [32]. One study from Massachusetts found bittersweet nightshade to be an indicator of low carbon to nitrogen ratios in the soil following high intensity tree harvesting [115]. In Europe, climbing nightshade is typically found in basic soils on sites rich in nitrates such as floodplains and thickets [43]. In the Netherlands, climbing nightshade is found in a range of substrates, from mineral soils to organic soils (peat) rich in nitrogen (Ellenberg 1979 cited in [131]).Impacts: A review indicated that climbing nightshade was typically not abundant or aggressive enough to require control [53]. The Nature Conservancy has given climbing nightshade a national ranking of "low" based on its overall low ecological impacts, but they are moderately concerned about its widespread distribution and abundance [126].
Climbing nightshade likely poses the greatest threat in portions of North America where it is most common (see General distribution), especially in riparian communities where it is most likely to be abundant (see Population structure and Site characteristics) ([46], reviews by [93,125,126]). On sites where it is abundant, climbing nightshade's ability to grow over trees and shrubs may cause changes in community structure (reviews by [93,117,126]) and, to a lesser extent, composition (review by [126]). In Oregon, Fierke and others [46] suggested that dense homogenous patches of climbing nightshade may inhibit germination and establishment of native plants. They further speculated that invasive species such as climbing nightshade may be a threat to successional development in cottonwood riparian forests.
In Oregon, climbing nightshade is ranked as "moderately invasive" in wetlands and riparian areas. Weeds with this ranking moderately impact native habitats but likely do not cause native plant or invertebrate extirpations [125]. An analysis of invasive plant survey data from the upper Great Lakes states ranked invasive species on their ability to invade natural plant communities. Climbing nightshade was given a 3.3 ranking on a scale of 0 to 10 (0 = little or no ecological impact, 10 = invades and replaces native plant communities) [136]. Field records from New England indicate that climbing nightshade typically occurs as a single plant or in small patches (1 to 20 plants) that comprise 5% or less of the overall vegetation cover. Larger populations (20-99 plants) of climbing nightshade occasionally occur, and on one site climbing nightshade cover was greater than 25% [117].
Climbing nightshade occurs in non-riparian sites; however, information pertaining to its invasiveness in these communities is limited. Although it occurs in non-riparian deciduous forest communities in eastern North America, available literature suggests that its abundance may decline or remain steady over time [79,85]. In the Great Lakes region, climbing nightshade is considered a "lesser invader" of forests and wetlands (review by [28]). Smith [150] speculated that climbing nightshade may not persist on dry sites over time, suggesting that its impacts in non-riparian areas may not be long-lasting (see Successional status).
Information pertaining to climbing nightshade's invasiveness in portions of North America where it is less common is limited and may indicate that its impacts are less severe in these areas. In Utah and the Great Plains, climbing nightshade is "rarely encountered" [64,174], in Colorado it was collected in only 1 drainage [172], and in North Carolina, bittersweet nightshade is rare and typically occurs in the mountains [134]. Although some of these reports are dated, a national invasive species database [126] indicates that climbing nightshade has not become more of a threat in these areas in recent times. Its ability to grow in warm climates suggests that it may continue to spread to other areas in the south (e.g. into Arkansas) (review by [126]).
In the Netherlands, climbing nightshade may be an alternative host for late blight (Phytophthora infestans), a pathogen that negatively impacts agricultural crops in the Solanaceae family. Infection in climbing nightshade, however, appears to be uncommon [49].
Control: Control of invasive plant species is most effective when it employs a long-term, ecosystem-wide strategy rather than a tactical approach focused on battling individual invaders [110]. Numerous methods have been suggested to control the spread of climbing nightshade, but information pertaining to their effectiveness in wildlands is limited. Regardless of the control method employed, removal of moderate to large infestations of climbing nightshade should be followed by replanting with desirable species to minimize reinvasion by climbing nightshade or other weeds. All treatments should be followed by monitoring for several years to help identify further infestations and determine survival of planted material (review by [93]). Prevention: Early detection followed by immediate eradication helps to prevent the spread of many invasive plant species. Small infestations of climbing nightshade are easy to identify from mid-May to late fall, when it is flowering or fruiting. Manual control of new infestations and subsequent site monitoring may help prevent initial infestations from spreading (review by [93]).Occasionally, climbing nightshade is still cultivated (review by [126]). Discouraging its commercial distribution and deliberate planting may help to prevent accidental introduction into native habitats.
Integrated management: Integrated management focuses not only on eradicating the target plant but also on establishing desirable species and maintaining weed-free systems over the long term. The King County Noxious Weed Control Program in Washington (review by [93]) recommends integrated management to maximize control of climbing nightshade and minimize negative impacts to the site. For large infestations, climbing nightshade can be cut with loppers or brushed mowed, followed by digging up roots or spot-spraying any remaining growth with an appropriate herbicide. As an alternative to herbicide, remaining growth can be covered with a heavy duty fabric to suppress further growth (review by [93]).
Physical or mechanical control: Climbing nightshade may be controlled manually by pulling or digging up the roots, which is easier when the ground is wet or loose (reviews by [28,53,59,93]). This method is most effective with young plants or new infestations (review by [93]). Care must be taken not to break the rhizomes or roots because fragments may regenerate vegetatively ([58,89], reviews by [93,183]).
Other physical or mechanical methods of control include repeat cutting or covering plants with a weed barrier (review by [93]). In a field in New York, however, repeat mowing failed to eliminate woody plant species including climbing nightshade [167].
Fire: See Fire Management Considerations.
Biological control: There are currently no biological control agents available for climbing nightshade (review by [93]).
Chemical control: Climbing nightshade may be controlled with selective broadleaf or broad-spectrum herbicides (reviews by [53,93]) but to what extent is uncertain. Following herbicide treatment, climbing nightshade should not be cut back until foliage turns brown or is dead (review by [93]). Several applications in the same year or consecutive years may be necessary for adequate control ([40], review by [93]). A few publications provide information on potential chemical treatments ([38,39,40], review by [93]). See The Nature Conservancy's Weed Control Method Handbook [161] for information on specific chemicals and how to correctly use herbicide in wildlands. Only herbicides approved for use in and near water can be used to control climbing nightshade infestations in riparian areas and other habitats adjacent to water. To prevent damage to desirable species, herbicide application should be done before other plants emerge or after they have gone dormant (review by [93]). For most weeds, 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 [20].
A 1919 review suggests that pouring hot brine or caustic soda around the roots will control bittersweet nightshade [59].
Cultural control: No information is available on this topic.
Although climbing nightshade is nonnative in North America, reviews indicate that it has food and cover value for wildlife [53,111,182,183], but it has not been reported as a major food source for any species with the exception of bumblebees. In Ontario, Canada, larval colonies of 2 species of bumblebees contained 64% to 71% bittersweet nightshade pollen [108].
Birds typically digest the fleshy portion of climbing nightshade's fruit and expel the seed (see Seed dispersal). Birds adapted to foraging in vegetation, which can reach fruit while perched on a branch and are not restrained by a small gape, are more likely to eat climbing nightshade fruit than birds lacking these characteristics [9]. Frugivorous birds such as crows [75], eastern kingbirds [106], mimic-thrushes, thrushes, white-crowned sparrow, and waxwings [8,154] eat the fruits of climbing nightshade. Numerous other songbirds and upland gamebirds throughout the United States also eat bittersweet nightshade fruit, especially in the Northeast and Southwest (review by [111]). Ring-necked pheasants eat the fruit of climbing nightshade [29,95], especially as an emergency food source during ice storms [29]. In the United Kingdom, climbing nightshade fruit is the primary food for blackcaps ([9], review by [151]) and is also used by blackbirds, song thrush, robin, starling, and spotted flycatcher. Bullfinches are the only known bird that regularly eats climbing nightshade fruit for its seed rather than its flesh (review by [151]).
Mammals that occasionally eat climbing nightshade fruit include black bear in Oregon [19], Virginia opossum in New York [70], eastern cottontail rabbits in Massachusetts [156], and white-tailed deer in the eastern United States [124]. A review indicated that common muskrats graze on the stems of climbing nightshade [53]. Herbivory by invertebrates on climbing nightshade has been reported in North America [168].
Palatability/nutritional value: The fruit of climbing nightshade is about 85% water [42,151,176] and may have low to moderate nutritional value. Herrera [76] calculated the relative yield (i.e., the dry, nutritive matter as a percent of total fruit mass) from available literature, for fruits of 15 tropical and 69 temperate bird-dispersed plants. Based on these calculations, the fruit of bittersweet nightshade had greater nutritional value than that of many plants with tropical origins, but less than that of many species of nontropical origins. A review by Snow and Snow [151] reported that the relative yield (i.e., the dry, nutritive matter as a percent of total fruit mass) for climbing nightshade fruit is low (12.5%) because the pulp is watery. When compared to fruits of other temperate region plants, climbing nightshade fruits contained near average percent nitrogen (1.15%) and carbohydrates (29.60%) but below average percent fat (1.00%) [8]. Together, the fruit and seed of climbing nightshade had a relatively high crude fat content (28%) [154], while the fruit pulp alone was low in lipids and calorie content [176]. An analysis of fruiting plants introduced to New Jersey found that the dry pulp of bittersweet nightshade fruit provided greater energy (18.63 kj/g) and contained more protein (6.2%) than that of most other introduced plants tested, but was low in fat ( 0.5% lipid) [176].
Climbing nightshade contains solanine (glycoalkaloid and alkamines collectively), a mildly toxic substance known to be poisonous ([42,81,88,159,178], review by [55]) to humans, livestock, mice, dogs and rabbits ([48,81], reviews by [53,55,104]). Unripe berries have the highest concentration of toxins, followed by vegetative tissue, and then ripe berries [55]. While some describe the amount of toxin in climbing nightshade as not "dangerously poisonous" (review by [59]), others report that children may be especially sensitive to it (review by [164]). A handbook on poisonous plants indicated that climbing nightshade is only likely to cause symptoms in humans who have eaten 10 or more unripe berries; a fatal dose would require about 200 unripe berries [55]. In large doses, solanine will slow the heart, reduce body temperature, cause vertigo, delirium, convulsions and possibly death (review by [104]). If ingested by horses, climbing nightshade can cause labored breathing, nausea, weakness, trembling, constipation, diarrhea, and possibly death [48]. Laboratory mice that ingested climbing nightshade fruit of various degrees of ripeness experienced gastrointestinal problems or behavioral changes [81].
Ripe climbing nightshade berries are also poisonous, which may reduce their palatability for some wildlife [8]. Evidence indicates that climbing nightshade is not toxic to birds ([8,9], reviews by [59,151]) but may be toxic to some mammals, which likely makes the fruit unpalatable. In a controlled experiment, climbing nightshade was found to be highly palatable to cedar waxwings, moderately palatable to American robins and white-crowned sparrows, and not palatable to yellow-pine chipmunks. A taste test determined that climbing nightshade fruit was not palatable to humans [8].
Cover value: While not preferred, climbing nightshade is occasionally used for nesting. Gray catbirds in the central portions of North America and Ontario, Canada, occasionally (< 1% of their nests) built nests in climbing nightshade [127]. American eiders nesting along Maine's Penobscot Bay occasionally used climbing nightshade; however, nesting success (i.e., percent hatched) was lower in nests constructed in climbing nightshade than in nests constructed in most native vegetation [22].
Although climbing nightshade has not been studied in North America for its associated
plant communities, a sufficient amount of incidental information is available to provide
a broad description of its typical associates in North America. Throughout its introduced
range, climbing nightshade most frequently occurs in riparian areas, wetlands, and
deciduous forests, but occasionally occurs in open habitats such as grasslands and meadows
in the Great Lakes region. It typically occurs as a minor component in most plant communities
but may be relatively abundant in riparian areas. Climbing nightshade's occurrence is
often associated with previous or ongoing anthropogenic disturbance.
Eastern North America and Great Lakes region:
In eastern North America and the Great Lakes region, including southern Ontario, bittersweet
nightshade is often associated with riparian and deciduous forests. Riparian communities in
these areas are often characterized by maple (Acer spp.) overstories with a mix of
other deciduous trees such as pin oak (Quercus palustris), ash (Fraxinus spp.),
cherry (Prunus spp.), basswood (Tilia americana), or American elm
(Ulmus americana) [3,27,45,71,79,83,116,121,157,166]. Climbing nightshade also
occurs on sites dominated by eastern cottonwood (Populus deltoides) [116]
that may contain a mix of sycamore (Platanus occidentalis) and American elm [83].
Climbing nightshade occurs in upland mesic deciduous forests with a similar composition of
overstory species and with other deciduous trees that may be more characteristic of mesic sites
such as American beech (Fagus grandifolia), northern red oak (Quercus rubra),
and slippery elm (Ulmus rubra) [10,11,27,35,45,85].
In one study, climbing nightshade commonly occurred in an eastern hemlock- (Tsuga canadensis)
dominated forest [83], and it may occur in coniferous forests dominated by northern whitecedar
(Thuja occidentalis) in Canada [11,35].
Climbing nightshade also occurs in open plant communities in eastern North America and the
Great Lakes region. It occurs in a variety of wetland plant communities often dominated by cattail
(Typha spp.) [3,4,67,77,157,165],
sedge (Carex spp.) [26,157,165],
Olney threesquare (Scirpus americanus) [30], or alder (Alnus spp.) [3,83].
It occurs in wetlands with other nonnative or invasive species such as purple loosestrife
(Lythrum salicaria) [3,30,67,77,129]
and reed canarygrass (Phalaris arundinacea) [3,77,148].
In the Great Lakes region, climbing nightshade occurs in a number of characteristically open
plant communities. In northern Illinois climbing nightshade occurs in calcareous wet places
with yellow marsh marigold (Caltha palustris), common boneset (Eupatorium
perfoliatum), field horsetail (Equisetum arvense), and other species associated
with this type of habitat. In southeastern Wisconsin, it occurred in mesic tussock sedge
(Carex stricta) meadows [26]. In southeastern Minnesota, climbing nightshade
was more often associated with wetlands with low plant density and tall vegetation. It was
also more commonly associated with wetlands characterized by narrow-leaf cattail than those
characterized by purple loosestrife [67]. In northern Illinois and east-central
Minnesota, climbing nightshade occurred with bur oak (Quercus macrocarpa) and
northern pin oak (Quercus ellipsoidalis) in a remnant oak savanna [12]
and in an oak forest where fire had been reintroduced over the last 20 years in an attempt
to restore the site to a savanna [160]. At Indiana Dunes National Lakeshore it occurred
in an oak savanna with black oak (Quercus velutina) along with a rich understory of
forbs and abundant grasses [107].
Western North America: Information
pertaining to climbing nightshade's occurrence in western North America comes primarily
from the northwestern United States. Climbing nightshade occurs in riparian areas
([46,47,101,112,137], reviews by [93,125])
and is most commonly associated with cottonwood (Populus spp.) [23,46,47],
native willow (Salix spp.), and alder [16,23,32,68].
It often occurs on disturbed sites with other nonnative or invasive species including
eggleaf spurge (Euphorbia oblongata), Canada thistle (Cirsium arvense),
common St. Johnswort (Hypericum perforatum), Himalayan blackberry
(Rubus discolor) [68], Russian-olive (Elaeagnus angustifolia), tamarisk
(Tamarix spp.) [16,32], and reed canarygrass [46,47].
In western Montana, climbing nightshade was one of the 15 most abundant plants
(0.1% - 2.0% average cover) in a riparian area invaded by Norway maple (Acer
platanoides) [137].
As of 2009, little published information is available regarding climbing nightshade's
distribution in western North America outside riparian areas. One study in California found
climbing nightshade on 1 plot (n=1,543) on a fuel break in an oak woodland [118].
Native range: Information pertaining
to climbing nightshade's associates in its native range comes primarily from the United Kingdom,
where it occurs in open woodlands or shrublands that are often associated with moist environments.
Climbing nightshade occurs on maritime-influenced sand dunes dominated by willows and other
shrubs where it comprises 1% to 40% of the vegetation cover. In one sand dune community characterized
by stinging nettle (Urtica dioecious), climbing nightshade cover can range between 41%
and 60%. In open habitats prone to weed invasion, climbing nightshade cover can range from 41% to
60%, and it is most common on sites characterized by common reed (Phragmites australis) [57,143].
It commonly occurs in willow and alder thickets and reaches its greatest cover (61% to 80%) in an
alder woodland community characterized by common reed [141]. Climbing nightshade occurs in a rush-
(Juncus spp.) dominated meadow fen where it can comprise 1% to 20% of the vegetation cover [142].
In England, climbing nightshade commonly occurs in woodlands dominated by birch (Betula spp.),
glossy buckthorn (Frangula alnus), willow, viburnum (Viburnum spp.), ash, pine,
and oak [61]. In early successional European beechwood (Fagus sylvatica) communities it
occurs in scrubland dominated by hawthorn (Crataegus spp.) and cherry, and with common
juniper (Juniperus communis spp.) and English yew (Taxus baccata) on calcareous soils
and exposed sites [171]. In central Europe, climbing nightshade occurs in floodplain habitats
dominated by willow, cottonwood, elm, oak, and alder [37,43,57].
In Hungary, climbing nightshade occurs in marshes, fens, and other types of wetlands
(Soo 1968 cited in [14]). In parts of Germany, climbing nightshade occurs in scrubland and
woodland [58,76,96].
Other: In New Zealand, climbing nightshade
occurred after fire in a dry, gorse- (Ulex europaeus) dominated bog [87].
Climbing nightshade has been studied primarily for its secondary chemicals (review by [14]) and used for its medicinal properties. Climbing nightshade contains small amounts of compounds that have been studied for their potential medicinal importance [80,82]. In North America climbing nightshade was widely prescribed for its narcotic, diuretic, alterative, and cleansing principles during the latter half of the nineteenth century. It was thought to relieve many ailments including leprosy, skin diseases, cutaneous diseases, rheumatic infections, ulcers, sores, and gland swelling. Although climbing nightshade is not widely used today, extracts from its roots, bark, and shoots are still prescribed for their narcotic principles in rheumatism, circulation, ulcers, and skin afflictions (reviews by [53,104]).
Climbing nightshade has been cultivated for ornamental purposes (reviews by [182,183]), and seeds are still available for purchase from online distributors. However, a review on seeds suggests that any ornamental values of climbing nightshade are offset by its poisonous properties [66].
In the spring, new branches of climbing nightshade grow from the woody base, spreading horizontally or climbing over other vegetation or structures ([150], review by [93]). Flowering period for climbing nightshade can be somewhat variable across its range but typically occurs throughout most of the growing season:
In North America, climbing nightshade berries are produced throughout summer and fall and may remain on the plant until winter (reviews by [59,182,183]). In the United Kingdom and parts of Germany, its berries may begin ripening toward the end of July, are most abundant between August and late September/early October [9,37], and may continue to be produced through at least early November [9]. In Sweden, climbing nightshade fruit persists on the vine for an average of about 20 days [44]. Climbing nightshade's branches from the current year die back 3 to 9 feet (1-3 m) or more (review by [53]) to the woody base each winter ([150], review by [183]). Germination tests indicate that most climbing nightshade seedlings emerge in spring (see Germination).
Research pertaining to the longevity, density, and vertical distribution of climbing nightshade seed in the soil seed bank is limited, and much of the information discussed below has been derived from germination studies conducted in controlled environments. Additional research is needed to more accurately characterize climbing nightshade's seed banking potential for wild populations.
Results of germination tests from North America and Europe suggest that climbing nightshade seed may have a transient seed bank or one that persists for only a short time. Some climbing nightshade seeds germinate shortly after dispersal while most other viable seeds tend to germinate by the following spring [1,119,138,139,150]. In germination tests, 62% to 80% of climbing nightshade seeds germinated within 1 year after planting outdoors [1,138]. In the laboratory, over 90% of climbing nightshade seeds germinated within 15 days. Seeds used in this experiment had their seed coats manually broken prior to experimentation and were grown in petri dishes that were exposed to adequate moisture, light, and temperature [119]. Approximately 80% of climbing nightshade seeds placed in dry storage for over 12 months germinated in an incubator with alternating temperatures [139], suggesting that bitterroot nightshade seeds may stay viable for longer than a year under some conditions.
Reported densities of viable climbing nightshade seed in the soil are low [17,94]. At Indiana Dunes National Lakeshore, researchers [107], using the seedling emergence method, estimated climbing nightshade average seed densities in an oak savanna to be 6 seeds/m² for soil samples collected to a depth of 4 inches (10 cm). Another study from southern Canada also used the seedling emergence method and estimated the average density of germinable climbing nightshade seeds in the soil seed bank to be less than about 3.4 seeds/m² from soil samples collected to a 4-inch (10 cm) depth in a deciduous forest. In that same study, researchers used the seed extraction method, which counts viable as well as non-viable seed, to estimate climbing nightshade seed density in the same forest. Density estimates obtained using the seed extraction method were higher (91 seeds/m²) than for those obtained using the seedling emergence method, suggesting that most climbing nightshade seeds in the soil were not viable [17].
Studies on bitterroot nightshade's soil seed bank often lack detailed information about its occurrence in the aboveground vegetation [17]; however, available evidence suggests that climbing nightshade seed density in the soil seed bank is minimally influenced by its abundance in the aboveground vegetation [11,33,71,77]. In Ontario, Canada, Booth and Larson [11] found no relationship between climbing nightshade's aboveground vegetation cover and seed rain for 3 different habitats. In Pennsylvania, seedlings of climbing nightshade did not emerge from any of the sampled plots (n=110), even though 2.1% of the plots contained climbing nightshade in the aboveground vegetation [71]. In the Great Lakes region, a small amount (0.14% mean cover) of climbing nightshade occurred in coastal wetlands that had been diked; however, it was not present in the seed bank [77]. In Great Britain, viable climbing nightshade seed was found in the soil seed bank, although it did not occur in the aboveground vegetation [33]. Two studies indicated that climbing nightshade occurred in both the aboveground vegetation and seed bank; however, abundance was not reported for either [105,107].
Climbing nightshade seeds are dispersed primarily by birds [76,97,98,150,154,155,175]. Birds consume the fleshy fruit, digest the pulp, and spread undamaged seeds by regurgitation or defecation [76,98]. In eastern states and the Great Lakes region, most climbing nightshade fruits were eaten and seeds dispersed shortly after fruits ripened in July and August [150,154]. Birds continued to forage on climbing nightshade fruit into the fall but to a lesser extent than in summer [150]. Mammals also eat climbing nightshade fruit and disperse its seed [124,155,156]. In eastern North America, Myers and others [124] concluded that white-tailed deer eat the fruit of climbing nightshade and have the potential to aid in the long distance distribution of its seed. See IMPORTANCE TO LIVESTOCK AND WILDLIFE for more information on animals that eat climbing nightshade fruit and seeds.
Seed rain (i.e., all seeds arriving at a site through various dispersal mechanisms) from climbing nightshade can be highly variable and may be influenced by habitat, site characteristics, or annual fluctuations in seed production or bird populations [11,98,150]. In Ontario, climbing nightshade mean seed rain over a 2-year period was significantly higher (P<0.1) on cliff faces than on the adjacent plateaus above the cliffs or in talus at the base of the cliffs. Greatest seed rain density for any one site in a given year occurred on talus. Climbing nightshade seed rain was greater in the 1st year of the study than the 2nd for all 3 site types [11], but reason for this variability was not reported.
Mean climbing nightshade seed rain density (seeds/m²) for three habitats in Ontario, over a 2-year period [11] Sites Year 1993 1994 Plateau Milton 0 0 Dufferin 16 0 Cliff face Milton 217 57 Dufferin 469 36 Talus Milton 609 0 Dufferin 0 0In a jack pine (Pinus banksiana) plantation forest in Illinois, Smith [150] used seed traps during the summer and fall over a 2-year period to estimate bittersweet nightshade's total seed rain. Average seed rain for the first year was about 4 seeds/m², compared to about 12 seeds/m² the following year. Many of the other species collected also had greater seed rain in the 2nd year, leading researchers to speculate that the difference between years was likely due to increased seed set and/or larger bird populations [150].
In western Germany, seed rain was collected across various habitats for 1 year. Average seed rain for climbing nightshade was about 0.2 seeds/square foot. Approximately half were dispersed from primary sources (intact fruit dropped due to ripening) and the other half from secondary sources (regurgitated or defecated by birds) [98].
Researchers in the field have observed climbing nightshade in various successional stages [5,12,46,87,123] and in a wide range of light levels [24,57,58], suggesting that it may establish and persist in a range of successional stages, from early to late succession. It may, however, fail to adapt to rapid increases in light where it is established in shade; rapid canopy removal may lower its productivity and inhibit its growth [57,92].
Shade tolerance: Climbing nightshade occurs in habitats ranging from full sun to deep shade in both its native European [57,58] and nonnative North American ranges [24]. Research has been conducted (see Plant growth and physiology) to determine if climbing nightshade's ability to grow in a full range of sun and shade habitats is genetic or phenotypic in origin [24,25,57]. Some evidence indicates that climbing nightshade is more likely to persist and spread on open or lightly shaded sites, while other evidence indicates a preference for shade. A review suggests that climbing nightshade plants in full sun or light shade produce more flowers and fruit than those in moderate to medium shade [53]. While seedlings of climbing nightshade may be shade tolerant and able to survive and grow under a moderate forest canopy ([150], review by [117]), climbing nightshade's productivity [24,25] and abundance [5,85] may decline with increased shade on some sites (see Potential successional stages). Conversely, data collected in a moist savanna remnant in Illinois suggest that bittersweet nightshade is more tolerant of shade than full sun in these communities. Climbing nightshade frequency was highest (25% and 22.9%) in plots with canopy shade and a mean photosynthetically active radiation (PAR) of approximately 143.1 and 164.7 mol/m²/s, respectively. Bittersweet nightshade frequency was 3.0% on plots with mean PAR of about 490.7 mol/m²/s, and it did not occur in canopy-gaps with a mean PAR of about 826.6 mol/m²/s [12]. Climbing nightshade's ability to take advantage of available light through alterations in morphology, biochemistry, and photosynthetic rates may facilitate its ability to grow in shade (see Population structure and Plant growth and physiology).
Potential successional stages: Climbing nightshade often occurs on disturbed sites where moisture is adequate (see Site Characteristics) and has been noted in early stages of succession after wildfire in New Zealand [87] and on old fields in the central United States [123]. In New Zealand, where climbing nightshade is also nonnative, it established in a shrub bog sometime after wildfire (see Fire adaptations and plant response to fire) [87]. In the central United States, natural revegetation occurred on previously cultivated land in a series of prairie pothole wetlands where the natural hydrological regime had been recently restored. Approximately 3 years after the wetlands were reflooded, climbing nightshade occurred on 5 of the 41 sites surveyed [123]. Smith [150] speculated that while climbing nightshade may colonize disturbed sites and openings, it may not be a major part of early succession because of its intolerance to drought and the tendency for its branches to die back in winter.
Climbing nightshade occurs in forest understories in much of its North American range (see Site Characteristics), including relatively undisturbed forests (e.g., [35,136]) and riparian areas [130], suggesting that it could occur in mid- to late-successional communities. Available evidence suggests, however, that it is more common in earlier stages of forest succession. Bittersweet nightshade is associated with the early-successional scrub stage of beech communities in England that are characteristically open [170]. A study in Norfolk, England found that climbing nightshade occurred in open, recently thinned (0-3 years since thinning) deciduous forests and was absent from forests that had not undergone recent thinning (4-33 years since thinning) [5]. In New York, climbing nightshade frequency decreased significantly (P<0.025) from 70% to 40% over 60 years in mesic deciduous forests in various successional stages. Although the authors did not speculate as to what caused the decrease in climbing nightshade, it did coincide with an increase in canopy cover, particularly of Norway maple [85]. In an urban riparian forest in Manitoba, climbing nightshade frequently occurred on shaded sites with approximately 75% canopy cover [121]. Climbing nightshade occurred in a remnant oak savanna in Illinois where fire had been excluded for more than 30 years. It was most frequent on sites with low light, and its frequency declined with increased light (see Shade tolerance and Fire management considerations) [12]. A chronosequence study in black cottonwood-dominated stands along the Willamette River in Oregon found that climbing nightshade occurred in all successional stages from stand initiation (1 to 5 years) to late seral (45 to >65 years). Climbing nightshade was most abundant, however, in the stem exclusion stage (4 to 7 years). In stands where climbing nightshade was most abundant, it codominated the riparian plant community, leading researchers to speculate that climbing nightshade may threaten successional development in some riparian forests (see Impacts and control) [46].
On sites where climbing nightshade is established in the shade, disturbance associated with an increase in irradiance may lower climbing nightshade's productivity and inhibit its growth [57,92]. Tolerance of shade-grown climbing nightshade to high irradiance may be decreased by even mild water stress [58]. Climbing nightshade plants grown in deep shade showed signs of damage on branches when grown at high light intensity in the laboratory [57]. In a greenhouse study, photoinhibition was achieved by transferring climbing nightshade plants from shade to 60% sunlight for 2 days. Flushes of nitrogen may offset photoinhibition in climbing nightshade; however, if accompanied by water stress, less protection from photoinhibition may be achieved [92].
Solanum dulcamara is a species of vine in the genus Solanum (which also includes the potato and the tomato) of the family Solanaceae. Common names include bittersweet, bittersweet nightshade, bitter nightshade, blue bindweed, Amara Dulcis,[3] climbing nightshade,[4] felonwort, fellenwort, felonwood, poisonberry, poisonflower, scarlet berry, snakeberry,[5][6][7] trailing bittersweet, trailing nightshade, violet bloom, and woody nightshade.
It is native to Europe and Asia, and widely naturalised elsewhere, including North America.
It occurs in a very wide range of habitats, from woodlands to scrubland, hedges and marshes.
Solanum dulcamara is a very woody herbaceous perennial vine, which scrambles over other plants, capable of reaching a height of 4 m where suitable support is available, but more often 1–2 m high. The leaves are 4–12 cm long, roughly arrowhead-shaped, and often lobed at the base. The flowers are in loose clusters of 3–20, 1–1.5 cm across, star-shaped, with five purple petals and yellow stamens and style pointing forward. The fruit is an ovoid red berry about 1 cm long,[8] soft and juicy, with the aspect and odour of a tiny tomato, and edible for some birds, which disperse the seeds widely. However, the berry is poisonous to humans and livestock,[9][10] and the berry's attractive and familiar look make it dangerous for children.
It is native to northern Africa, Europe, and Asia, but has spread throughout the world. The plant is relatively important in the diet of some species of birds such as European thrushes,[11] which feed on its fruits, being immune to its poisons, and scatter the seeds abroad. It grows in all types of terrain with a preference for wetlands[12] and the understory of riparian forests. Along with other climbers, it creates a dark and impenetrable shelter for varied animals. The plant grows well in dark areas in places where it can receive the light of morning or afternoon. An area receiving bright light for many hours reduces its development.[12] It grows more easily in rich wet soils with plenty of nitrogen. When grown for medicinal purposes, it is best grown in a dry, exposed environment.[13]
It is a nonnative species in the United States.[14]
Solanum dulcamara has been valued by herbalists since ancient Greek times. In the Middle Ages the plant was thought to be effective against witchcraft, and was sometimes hung around the neck of cattle to protect them from the "evil eye".[15][16][17]
John Gerard's Herball (1597) states that "the juice is good for those that have fallen from high places, and have been thereby bruised or beaten, for it is thought to dissolve blood congealed or cluttered anywhere in the intrals and to heale the hurt places."[17]
This plant is one of the less poisonous members of the Solanaceae. Instances of poisoning in humans are very rare on account of the fruit's intensely bitter taste. Incidentally, the fruit has been reported to have a sweet aftertaste, hence the vernacular name bittersweet.[18]
The poison in this species is believed to be solanine.[19] The alkaloids, solanine (from unripe fruits), solasodine (from flowers) and beta-solamarine (from roots) have been found to inhibit the growth of E. coli and S. aureus.[20] Solanine and solasodine extracted from Solanum dulcamara showed antidermatophytic activity against Chrysosporium indicum, Trichophyton mentagrophytes and T. simil, thus it may cure ringworm.[21]
The stems are approved by the German Commission E for external use as supportive therapy in chronic eczema.[22]
Solanum dulcamara has a variety of documented medicinal uses, all of which are advised to be approached with proper caution as the entirety of the plant is considered to be poisonous. Always seek advice from a professional before using a plant medicinally. There have only been records of medicinal use for adults (not children) and it is possible to be allergic to Solanum dulcamara; medicinal use is not advised in these cases.[23]
The stem of Solanum dulcamara is believed to be considerably less poisonous than the rest of the plant, and it has mostly been used in treatment for conditions of the skin. There are records of it being used to treat mild recurrent eczema, psoriasis, scabies, and dermatomycosis.[24][25] Stems are harvested when they do not yet have leaves (or the leaves have already fallen) and are shredded into small pieces. They are mostly known to be applied in the form of liquid onto the skin, but infusing it into a drink is also possible, though not recommended.[26] The stem has also been used in treatment for bronchitis, asthma, and pneumonia.[25]
The leaves of Solanum dulcamara have been known to treat warts and tumors, while the fruit can treat conditions of the respiratory tract and joints.[23] It has been documented that Indigenous people of North America used the roots for relief of fever and nausea.[27]
Solanum dulcamara has been used as a symbol of fidelity. This is in reference to its curious property of combining extreme bitterness with surprising sweetness - hence its common name "bittersweet." This symbolism is seen in Christian art from the Middle Ages as well as in bridal wreaths.[28]
Bittersweet exists on a balance between sweet and bitter, medicine and poison, life and death; lending it to be a common metaphor. Shakespeare has been known to employ this metaphor in dramas such as Macbeth and The Winter's Tale.[29]
Perhaps this parallelism has been used more directly by Italian composer Gaetano Donizetti in his opera L'Elisir d'Amore (Love Elixir). Here, a Dr. Dulcamara sells the protagonist, Nemorino, a love elixir at the cost of his fortune. However, this "love elixir" is actually just cheap red wine. Under the illusion of a love elixir (and drunkenness), Nemorino, is confident to profess his love to an indifferent woman, Adina. Upon independently learning of Nemorino's fidelity by spending his fortune, Adina subsequently falls in love as well. Dr. Dulcamara has bitterly sold a fake elixir that had turned out to have sweet consequences anyway. This happy unexpectedness is at the heart of Solanum dulcamara.
Flowers
Fruits
Solanum dulcamara
Bittersweet Nightshade in Clark County, Ohio.
Bittersweet after rain in Boston, Massachusetts
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Solanum dulcamara is a species of vine in the genus Solanum (which also includes the potato and the tomato) of the family Solanaceae. Common names include bittersweet, bittersweet nightshade, bitter nightshade, blue bindweed, Amara Dulcis, climbing nightshade, felonwort, fellenwort, felonwood, poisonberry, poisonflower, scarlet berry, snakeberry, trailing bittersweet, trailing nightshade, violet bloom, and woody nightshade.
It is native to Europe and Asia, and widely naturalised elsewhere, including North America.
