Nightshades
What are they?
This group of plants consists of mostly introduced members of the nightshade family (Solanaceae) and contains an interesting mix of species that have fruits which can be either edible or potentially very poisonous. It therefore follows that being able to recognise them can be of great importance. It does seem perverse that we can eat tomatoes, a fruit that is not only red - the colour of danger - but which also grows on a plant that is a member of such a potentially poisonous family. Similarly, we eat the tuberous roots of the potato, but its fruits can be very poisonous to us. The answer is in the way that the plants localise the poisons that they manufacture, such that various parts of the various species can be eaten in some cases. Nightshades are attractive plants and many are grown as garden ornamentals as well as crop plants.
Where are they found?
The great majority of these plants are introduced species which are most likely to be found in human-influenced habitats such as gardens, allotments and arable fields.
Identification
The colour of the flowers and shape of the petals will narrow down your search initially. Leaf shape and fruit details are also important, the latter especially in the green-fruited species that grow on disturbed ground. The flowers have five petals which may be fused at the base or for much of their length to form a flat or slightly bell-shaped flower. Alternatively, the petals may be more or less free and strongly reflexed to form a 'shooting star'. In most species, the yellow stamens are fused into a beak-like column projecting from the centre of the flower. Fruits are fleshy with many seeds inside, typically starting green in colour. Thus, care should be taken in being sure that a fruit is ripe before the colour is used for identification, since some species have fruits that remain green when ripe, while others ripen to yellow, orange, red or black.
Bittersweet Solanum dulcamara
(Woody Nightshade) Native. A scrambling perennial plant, widespread in all but the driest, sandy soils. A highly adaptable plant, found naturally in wetlands (especially species-poor reed stands) and on shingle beaches but also regularly as an arable and ditchside weed. Flowers June to September. Leaves variable, from simple to unevenly lobed at the base. Stems thin and tough, scrambling and sometimes twining through and over other vegetation. Note that many people erroneously know this plant as Deadly Nightshade, which is a much rarer species with very different flowers and black berries (see below).
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Black Nightshade Solanum nigrum
Native or perhaps an ancient introduction. An annual of usually enriched soils in cultivated and disturbed ground. Flowers July to September. Leaves very variable with a number of varieties described, based largely on the variability of leaf-edge lobing and hairiness. Fruits green at first but ripening black.
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Scabrous Nightshade Solanum scabrum
Introduced, initially accidentally but more recently as a pest management species. Flowers July to September. Very like a rather large Black Nightshade, to a metre in height, with noticeably coarsely winged angles to the stems. Berries black when ripe. So far only recorded in our area from near Cambridge but the species is increasingly being used (along with other nightshade species) for Potato Cyst Nematode control and may appear self-seeded on field margins in the near future.
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Green Nightshade Solanum nitidibaccatum
Introduced from South America. A low-growing plant of disturbed, sandy ground, most frequent in Breckland and the Suffolk Sandlings. Flowers July to September. Leaves and stems slightly sticky with glandular hairs. Fruits green, sometimes with a dull, brownish cast; sepals rather broad and short and not hiding the berry.
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Leafy-fruited Nightshade Solanum sarrachoides
Introduced from South America. A rare casual in the UK which in the past has often been confused with Green Nightshade. No confirmed records in East Anglia but included here for completion because of past confusion between the two species. Flowers July to September. Similar to Green Nightshade but leaves typically with a more waved or toothed margin. Fruits green, sometimes with a dull, brownish cast; sepals relatively narrow and long and partly concealing the berry.
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Red Nightshade Solanum villosum
Introduced from southern Europe. Recorded on just two occasions in West Norfolk and Cambridge but possible as an unintended introduction from various seed sources. Flowers July to September. Very similar to Black Nightshade but typically more obviously hairy all over, often including the petals. Most easily identified in fruit as its berries ripen from green to orange-red.
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Tall Nightshade Solanum chenopodioides
Introduced from South America, perhaps as a seed contaminant of imported products. Remains very rare in our region, with single records from West Norfolk and Cambridgeshire and recently confirmed in Suffolk in 2023 as an urban weed. Flowers June to August. Superficially similar to Black Nightshade but this is a perennial species that develops a woody stem and branches and may reach over 3m in height! Leaves are rather narrow and have downy hairs. Berries turn from green to black but remain dull rather than glossy.
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Small Nightshade Solanum triflorum
Introduced from South America. Rare as an occasional short-lived population but long-established in Suffolk Breckland in sandy soil on field margins. Flowers July to September. A small, branching annual, easily identified by its deeply cut leaves and marbled fruits.
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Red-fruited Buffalo-bur Solanum sisymbriifolium
Introduced from North America with a handful of records from across the region in garden waste, dumped soil and on rough ground. Records may increase as the species has recently been used in the control of Potato Cyst Eelworm. Flowers June to September. Somewhat resembles a small potato plant in its flowers, but has deeply cut rather than pinnate leaves and has spines on stems, leaves and sepals.
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Carolina Horse-nettle Solanum carolinense
Introduced from North America. Recorded once in Suffolk as a weed in imported soil. Flowers June to October. Leaves with a row of spines on the underside along the midrib. Flowers white or lilac. Fruits dull yellow when ripe.
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Tuberous Potato Solanum tuberosum
Introduced from South America and now widely grown as a root vegetable on a commercial scale. Odd plants may turn up almost anywhere when root tubers fall off farm trailers and find their way into field margins and roadsides. Flowers June to September. The dull greenish or brownish fruits are poisonous and should not be eaten.
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Chinese-lantern Alkekengi officinarum
(Japanese Lantern) Introduced from Southern Europe as a garden ornamental and occasionally spreading from discarded garden material. Flowers July to August. Forms spreading mats of suckering stems to around 60cm in height. Flowers are small and easily missed but are followed by brilliant orange, inflated fruits that carry an orange-red berry inside.
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Cape-gooseberry Physalis peruviana
Introduced annual or short-lived perennial from South America as an exotic fruit and occasionally found in the past on old tips or where treated sewerage has been spread on fields. Flowers June to August. A rather sprawling species with relatively large leaves. Petals with dark blotches and calyx densely hairy.
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Common Tomato Solanum esculentum
Introduced from South America for its edible fruits. A scrambling plant which is frequently found self-sown on rough ground, allotments or where some kinds of treated manure or effluent are spread on farm fields. Flowers June to September or until killed by frost. Leaves pinnate with irregular-sized leaflets, stickily-hairy and rather pungent. Fruits very variable due to selective breeding and may be green, yellow or red and seemingly almost any shape, but generally larger than the small berries of other nightshade species.
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Beaked Buffalo-bur Solanum rostratum
Introduced from North America with a handful of records from across the region in garden waste, dumped soil and on rough ground. Flowers June to August. A very distinctive plant, the flowers having a long, curved 'beak' and the stems and fruits well-armed with long spines.
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Common Kangaroo-apple Solanum laciniatum
Introduced from Australia as a garden ornamental and probably not fully frost-hardy. Recorded a couple of times in Suffolk from discarded garden waste. Flowers June to September or until hit by frost. Leaves with long, slender leaflets and often unevenly pinnate. Fruits oval, ripening yellow or orange.
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Mountain Kangaroo-apple Solanum linearifolium
Introduced from Australia as a garden ornamental and probably not fully frost-hardy, but capable of regenerating from seed. Recorded in Norfolk where self-sowing in a churchyard in 2018 from an original planting. Flowers June to September or until hit by frost. Leaves long and very slender; typically simple but sometimes with a narrow pair of leaflets towards the base. Fruits oval, ripening yellow or orange. Overall smaller in all its parts than Common Kangaroo-apple.
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Deadly Nightshade Atropa belladonna
Native perennial, persisting where left undisturbed but perhaps mostly surviving as a relic of cultivation as most locations are close to or within built up areas. Flowers July to September. A highly poisonous shrub to 1.5 metres in height. Sadly much maligned for its poisonous properties which instills fear in people, but it is fully innocuous if left alone and an attractive native plant. Many locations are kept secret to protect the plants from being destroyed.
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