What is a Nightshade Plant?

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Nightshade plants belong to the genus Solanum.

Nightshade plants, often referred to as deadly nightshade, are a variety of plant species that falls under the genus Solanum. These plants are frequently considered weeds and cause problems for farmers and gardeners alike. A wide variety of nightshades exists, many of which invade gardens and reduce the yield of crops like potatoes and peas.


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Nightshade Plants

Solanaceae plants, or nightshade plants, are a serious weed problem throughout areas like the Pacific Northwest. Some plants in the nightshade family are Solanum physalifolium, or hairy nightshade, S. nigrum, or black nightshade, and S. triflorum, or cutleaf nightshade. Many nightshade plants are annuals that reproduce by putting out seeds at the end of their growing season, which will sprout again the following spring.

Effects on Mammals

Plants of the nightshade family are highly toxic to livestock like cows and horses. Animals that feed on nightshade plants become extremely ill, and large amounts of nightshade are often fatal. Keep fields and grazing areas free of nightshade plants. Humans are also susceptible to deadly nightshade; if the plant is eaten, the individual requires immediate hospitalization or emergency medical attention. The species that earns the name deadly nightshade is Atropa belladonna, or the belladonna plant.


Effects on Gardens

Nightshade plants are considered weeds. They invade cultivated garden areas and compete with established garden plants such as beans, peas and potatoes for resources such as water, nutrients and light. The plants twine themselves throughout the growing area of a garden, making extraction more difficult and sometimes dramatically reducing the yield of the plants they are growing among. Removing nightshade early in the growing season and tilling to kill sprouts in the spring is important for gardeners.



Nightshade plants often produce erect or spreading branches, berries and elliptical or egg-shaped leaves. The flowers have five petals and are about 1/4 inch across; they appear on the plant in clusters. Identifying nightshade plants helps gardeners and farmers remove them more easily, which protects both crops and livestock from problems with the weeds. Remove and dispose of nightshade plants as they are identified.