What are nightshades?
The nightshade family (Solanaceae) is a large and popular family of plants. There are about 2700 species in this family (source). They include crops such as potatoes (Solanum tuberosum), tomatoes (Solanum lycopersicum) and tobacco (Nicotiana tabacum).
Some nightshades are used as ornamentals, such as petunias (Petunia sp.), of which there are many cultivated forms.
Belladonna (Atropa belladonna) is valued as a medicinal plant.
What many nightshade plants have in common is that they are poisonous. Tomatoes are edible only when ripe. Their green parts are not fit for human consumption. The same applies to the leaves and small berries of potatoes.
The following members of the Solanaceae family are well-suited for survival in urban areas:
Thorn apple, jimsonweed (Datura stramonium)
The thorn apple or jimsonweed is believed to originate from Mexico (source). It can grow up to just over a meter in height and displays its pale lilac, light yellow, or white flowers from June to September.
Datura stramonium is an annual plant and can be found along roadsides, in weed patches, and on construction sites.
Black nightshade, blackberry nightshade (Solanum nigrum)
Based on my observations, the black nightshade is the Solanaceae plant that is best adapted to urban areas. It grows along roadsides, on walls and steps, in parks and gardens, and can even establish itself in flower pots on balconies.
Hairy nightshade, red nightshade (Solanum villosum)
The hairy, wolly or red ightshade closely resembles the black nightshade and can be differentiated by its red or orange berries.
Solanum villosum appears to prefer warmer temperatures compared to Solanum nigrum, but colonizes similar habitats.
Bittersweet (Solanum dulcamara)
In contrast to the previously mentioned species, bittersweet is a perennial plant. It blooms from June to September and sheds its leaves in autumn. Its shoots can reach several meters in length and become woody at the base.
