Tag Archives: Solanum

Delight and Disaster in the Rubbish Heap

I’m always keen to add to the number of plants I can recognise. Weeds are a profitable group in that respect.

One of the species of poroporo, Solanum aviculare. Photo © Leon Perrie.

Recently my wife pointed out an interesting looking organic rubbish heap on the grounds of Massey University that was home to an odd-looking Solanum. Imagine my delight when, on closer inspection, I found it to be not a weedy exotic but a real indigenous treasure: Solanum aviculare.

Solanum aviculare is one of two similar species known as poroporo. The other is Solanum laciniatum, which is very common and widespread through New Zealand. Solanum aviculare, on the other hand, is on the Threatened Plants lists as “At Risk/Declining”. I have never knowingly seen it before, so I was very excited!

Handily, at this rubbish heap the two species of poroporo were growing together, facilitating easy comparison. Although their leaves were strikingly different here, the best way to distinguish them is by their flowers: the petals of S. aviculare are less fused and more deeply cut than those of S. laciniatum.

The two poroporo side-by-side. Solanum laciniatum is on the left, Solanum aviculare on the right. Photo © Leon Perrie.

Flowers of the two poroporo. Solanum laciniatum is on the left, Solanum aviculare on the right. Photos © Leon Perrie.

The DISASTER comes because a week after taking these pictures, this rubbish heap was “cleaned up” – an unfortunate demise for this rarity! Hopefully we can find more S. aviculare locally.

Unripe fruit of poroporo, Solanum laciniatum. Photo © Leon Perrie.

Both poroporo species have similar fruit, which can be eaten when they are ripe (when orange, with bursting skin). However, they’re poisonous when green and unripe, so be wary! They belong to the same genus as tomatoes, potatoes, and black nightshade, and the same family as deadly nightshade. It’s a minefield of nutrition and toxicity.

Interestingly, both Solanum aviculare and S. laciniatum occur in Australia, where they are known as kangaroo apple.

Black Nightshade – it’s (nearly) everywhere

Black nightshade has been in the news recently, after its berries turned up masquerading as peas in packs of frozen vegetables.

Leaves, ripening fruit, and a flower of black nightshade, Solanum nigrum.

Leaves, ripening fruit, and a flower of black nightshade, Solanum nigrum.

Without wanting to be seen to cast aspersions on your aptitude for gardening, there is a good chance black nightshade is in your garden.
Black nightshade is a small plant (less than 75 cm tall) that is common in lowland New Zealand. It is usually in disturbed habitats, and it is a frequent weed of gardens (including my own!) and crops. In horticultural settings, black nightshade is often controlled by herbicides, but some populations have developed resistance.

 

Black nightshade is regularly confused with deadly nightshade. Indeed, the picture in the above news story appears to be of deadly nightshade, although it is labelled black nightshade. Fortunately, deadly nightshade (Atropa belladonna) is quite rare in New Zealand, only occurring in the wild in Canterbury. Black nightshade is thought to be no where near as toxic as deadly nightshade.  Nevertheless, I suspect no-one would recommend it for human consumption.

Black nightshade belongs to the genus Solanum, which also includes tomatoes (Solanum lycopersicum) and potatoes (Solanum tuberosum)!

Black nightshade (Solanum nigrum) is easily confused with small-flowered nightshade (Solanum nodiflorum, previously known in New Zealand as Solanum americanum). The former is introduced to New Zealand; the latter is thought to be native. They differ in chromosome numbers, but appear very similar externally. Barry Sneddon, one of the Botany Collection Managers, and I have been learning how to distinguish them.

Flora of New Zealand Volume 4 suggests that in:

Solanum nodiflorum (previously known in New Zealand as Solanum americanum)
* the calyx is strongly reflexed at fruiting.
* the flowers/fruit in a particular group all branch from more or less the same point.
* stone cells are evident in the fruit.

Solanum nigrum
* the calyx is not or only partially reflexed at fruiting.
* some flowers/fruit in a particular group clearly branch below the others.
* stone cells are usually absent in the fruit.

Left, unripe fruit of Solanum americanum; right, ripening fruit of Solanum nigrum.  The calyx of S. americanum is strongly reflexed (the green triangles between each fruit and its stalk point away from the fruit).  Stone cells are also just evident in the S. americanum fruit, as white speckles.

Left, unripe fruit of Solanum nodiflorum; right, ripening fruit of Solanum nigrum. The calyx of S. nodiflorum is strongly reflexed (the green triangles between each fruit and its stalk point away from the fruit). Stone cells are also just evident in the S. nodiflorum fruit, as white speckles.

As indicated by the blue arrows, the fruit (or flowers) of Solanum americanum (left) branch from nearly the same point, while at least some of those of S. nigrum (right) clearly branch lower.

As indicated by the blue arrows, the fruit (or flowers) of Solanum nodiflorum (left) branch from nearly the same point, while at least some of those of S. nigrum (right) clearly branch below the others.

From this, it appears that the plants in my garden are actually the native Solanum nodiflorum. Which, as a lover of native plants, is a good thing, I suppose. But they still look weedy…

Te Papa has a specimen collected during Captain Cook’s first expedition that has been labelled as Solanum nigrum; however, this would seem to be a mis-identification.

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