Solanum dulcamara var. dulcamara L., Solanum dulcamara var. villosissimum Desv., bitter nightshade,  climbing nightshade,  climbing bittersweet, blue nightshade, European bittersweet, woody nightshade, deadly nightshade, fellenwort, felonwood, poison berry, scarlet berry, shooting star, violetbloom

Leaves are dark green with a purplish tint and are connected to the stem via petioles (stalks) in an alternate pattern (Campbell et al. 2010, OARDC Extension 2013). Leaves can be 1-4 inches long and have smooth edges (King County 2010, OARDC Extension 2013). The smaller leaves are oval shaped with a pointed tip and the larger leaves tend to have three lobes: the terminal lobe is bigger than the two lateral lobes (Campbell et al. 2010). Leaves emit an unpleasant smell when crushed (King County 2010).

The blue-violet (on rare occasions white) flowers are star-shaped with 5 recurved petals that join at the base (OARDC Extension 2013). At the center of each flower are bright yellow fused anthers (Campbell et al. 2010). The flowers, which are ½ inch wide, grow in dropping clusters along that are opposite the leaves on the mains stem (King County 2010, OARDC 2013). Flowers are in bloom from May to November (Campbell et al. 2010).

The thin-skinned berries are round to egg-shaped and less than ½ inch wide (King County 2010, OARDC Extension 2013). As these hanging clusters of berries ripen, they change color from green to orange, and are ripe once they become bright red (Forest Health Staff 2006, King County 2010). Ripe berries contain numerous flattened yellow seeds (King County 2010, OARDC Extension 2013). 

All stages of flower and berry development can be found on the same individual plant (King County 2010).

Bittersweet nightshade flowers from May to November (Campbell et al. 2010). Fruit and seed production can be abundant; each berry can have about 30 seeds (King County 2010). Plants spread to new locations by birds eating the ripe berries and by stem/root fragments moving in soil or water (Campbell et al. 2010, King County 2010, Waggy 2009). New plants are created from a parent plant by way of suckering roots, prostrate stems rooting at nodes, and by growing up and over vegetation or structures like fences and buildings.

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Socioeconomic	Beneficial

The vines of S. dulcamara can grow over nearby trees and shrubs, and even pull down smaller plants (Forest Health Staff 2006, IPANE  2013). This growing ability can quickly lead to dense thickets of bittersweet nightshade (King County 2010). Solanum dulcamara can also become dominant along small waterways and alter the flow of water (King country 2010).

Bittersweet nightshade is abundant throughout Michigan and Ohio (OARDC Extension 2013, Reznicek et al. 2011). The New York Invasive Species Council ranks this species at moderate ecological risk (New York Invasive 2010). Falck and Garske (2002) acknowledge that, given this species' small size and ability to thrive in forested areas, data about its presence is likely underrepresented.

Potential:
In studies conducted in New Zealand, species within the Solanum genus showed resistance to hybridization (Armstrong et al. 2005). This indicates that S. dulcamara may pose only a small genetic threat to native or crop species.

Water extract from the leaves of S. dulcamara significantly inhibited the growth of Pinus resinosa seedlings; however, this allelopathy has not been studied in the field (Waggy 2009).

Solanum dulcamara has a moderate socio-economic impact in the Great Lakes.
Realized:
All portions of this plant are poisonous (Forest Health Staff 2006). It has been reported that paralysis can occur in humans after consuming only 6 berries (OARDC Extension 2006). Poisoning from S. dulcamara has been reported in cattle, sheep, and horses (OARDC Extension 2006).

Potential:
Bittersweet nightshade can act as a host for Leptinotarsa decemlineata (Colorado potato beetle). This beetle can invade species from the Solanaceae family, such as potatoes and tomatoes, and could damage the crops (IPANE 2013, OARDC Extension 2006). However, success of beetles reared on S. dulcamara varied depending on seasonally varying phytochemicals present in the plant (Hare 1983). Solanum dulcamara can also host two other pathogens: Phytophthora infestans (causes potato blight) and Ralstonia solanacearum (causes brown rot in potatoes) (Golas et al. 2010, Knapp 2013).

There is little or no evidence to support that Solanum dulcamara has significant beneficial effects in the Great Lakes.
Realized:
Extracts from the roots, bark, and stems of S. dulcamara have been used to relieve pain caused by rheumatism, poor circulation, ulcers, and skin afflictions. Currently, these extracts are not widely used (Waggy 2009).

Potential:
Solanum dulcamara contain glycosides; which can be used in the production of steroidal hormones (Curtis et al. 2000).

Alcoholic extracts of S. dulcamara, taken from plants grown in New York and Wisconsin, exhibited tumor-inhibitory activity in mice (Kupchan et al. 1965).

As of 2011, the Great Lakes Indian Fish & Wildlife Commission ranked S. dulcamara as a “lower priority” (Falck et al. 2012).

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control
Biological
There are no known biological control methods for this species (King County 2010).

Physical
Solanum dulcamara may be controlled by manually digging up the roots; most effective with the plants are young and the soil is moist (Waggy 2009). All parts of the roots should be removed to prevent regrowth (King County 2010). Gloves should be worn when handling this species to prevent skin irritation (King County 2010).

Mowing is not a practical method for control because this species can resprout from the suckering roots and rhizomes; however it may be useful when manually removing the root system (King County 2007). If mowing is the only option, it must be done several times during the growing season to be effective (Forest Staff Health 2006).  Another option would be to cover the cut plants with a heavy geotextile cloth for two years to prevent photosynthesis and regrowth (King County 2010).

Chemical
Larger infestations may require the use of an herbicide (Forest Staff Health 2006). The herbicide Clopyralid (Transline®, Stinger®, Reclaim®, and Curtail®) is effective on Solanaceae (Tu et al. 2001).
Triclopyr is effectively taken up in the woody stems, roots, and leaves of bittersweet nightshade. It is also unlikely to harm nearby grasses, sedges, rushes, cattails, lilies, and irises (King County 2010).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.