Ranging from low weeds to large bushes the nightshades all have one thing in common – they are definitely not for eating. Of interest is the fact that, while we are likely to refer to the small varieties as ‘deadly nightshade’, that is actually a whole different species (Atropa bella-donna) which is extremely rare in New Zealand.
There are two native nightshades (Solanum aviculare and Solanum laciniatum) both known by their Maori name of ‘poroporo’. Tall and spreading bushes with long and heavily veined and hairless dark green leaves, green or purplish stems, trumpet shaped mauve flowers with yellow centres, and drooping single oval green berries which turn orange as they ripen. Aviculare is found mostly on bush margins, roadsides and waste places, while laciniatum is more often found in scrub, in plantations or on forest margins. They bloom all year round.
A differently shaped variety is Solanum dulcamara or bittersweet, which clambers along fences, hedges and damp waste places. The purple flowers have the familiar turned-back petals with a protruding yellow centre, and the small round berries hang in clusters, turning from green to bright red. The bright green leaves are egg shaped with pointed tips and stalked bases. Originally from Eurasia and North Africa, it is now found in the southern half of the NI and occasionaly in Buller and Canterbury.
There are prickly varieties too, such as Solanum linnaeanum or Apple of Sodom. This has spiny stems and deeply lobed and curly leaves which are shiny on top and downy underneath. The purple flowers are up to 3cm across and trumpet shaped, and the berries hang singly, mottled green to start and ripening to yellow, like small yellow apples.
White-edged nightshade (Solanum marginatum) grows up to 5m tall. Its stems and the undersides of the leaves are white and felted looking, and the leaves have white margins. This one has white flowers, sometimes with purple veins. It grows in waste places as far south as Banks Peninsula, and is listed as a national pest plant.
A nightshade which likes company of its own kind is the small tree woolly nightshade (Solanum mauritianum). The mauve flowers are tiny, but grow in terminal corymbs or clusters, and the berry clusters turn from green to dull yellow. The leaves are velvety and grey/green, pointed at both ends and up to 25mm long. Left to itself it will grow until the trunk is about 15cm thick. Considered a plant pest in various parts of the country, it would pay to check with your local Council for their ruling on it. Originally from South America it is well established in northern parts and is spreading southwards to Nelson and beyond.
Probably the most often found variety is the annual black nightshade (Solanum nigrum). This can vary from just a few centimetres tall up to 75cm or so, with bigger plants often extensively branched. Small white or mauve flowers with turned back petals and hanging yellow centres, and smallish clusters of berries which turn black as they ripen. While it’s a common weed of gardens and pasture, it also is a serious weed in pea crops, where the green berries can be harvested with the peas. For infestations in waste areas it can be mown, or pulled, or treated with most herbicides. However, Massey University research has found increasing resistance to some herbicides where black nightshade is growing among pea or maize crops, and in orchards where sprays such as simazine are used season after season.
While not every part of every Solanum variety is poisonous, it should be removed where there are children or stock. If varieties are growing in waste places on or near your place, check with your Council on their pest status for your area.