Cross breeding a poisonous and non poisonous plant*


Hi there! I was wondering what would happen if I crossbred, for example, a cherry tomato plant with a nightshade plant etc. Would the outcome be a non poisonous plant or a poisonous plant? I’m quite interested in the result, as it will be a large part of my summer crop!

Thank you so much!


What an interesting question!! It’s unclear as to why you are interested in crossing those related plants; nevertheless, it’s definitely food for thought.

Both the tomato and (bittersweet or “deadly”) nightshade plants are members of the same genus, Solanum. As you may be aware, Solanum is a very large and diverse genus of between 1500 and 2000 species; it includes cultivated food crops such as potatoes (Solanum tuberosa) and eggplants (Solanum melongena) as well as tomatoes (Solanum lycopersicum). The family of plants is known as the Solanaceae or Nightshade family. The common nightshade plant to which you refer would be Solanum dulcanara; it is a perennial vine originally from Europe, but is now widespread throughout North America. Although it is sometimes referred to as “deadly nightshade” and because the stems and leaves are potentially poisonous in large quantities to livestock, it is actually not in the same genus as Atropa belladonna, an extremely toxic plant that is more aptly known as Deadly Nightshade. According to the OMAFRA Ontario Weeds site, the bright red berries can apparently be eaten without harm by some people; however, it is recommended that children should not ingest them. It seems that the plant you want to ‘cross’ with the tomato plant is really not significantly poisonous to humans in spite of its common name.

For many years, the tomato was considered poisonous in parts of Europe and North America until the early 1800s. Even though the leaves, stems, roots and unripe fruit of plants of the Solanum genus contain glycoalkaloids, such as tomatine and solanine, the presence of these alkaloids in tomatoes and potatoes will not produce any toxic effects after normal consumption of the fruit. Obviously, tomatoes are consumed and enjoyed throughout the world today with no ill effects. But there is some concern about the toxicity, if any, in the foliage of tomato plants. The common thought is that the leaves are toxic if eaten; for sure, their pungent scent would not encourage them to be eaten, but apparently some people have used them in sauces with no toxic effects.

Even though there may be potentially more toxicity in the Solanun dulcanara compared to Solanum lycopersicum, the difference in levels of ‘poison-ness’ would not be significant.

Now to answer your first question–what would happen if…? Both plants are self-pollinating as the flowers have both female/male parts; bees also help to move pollen from one flower to another, ensuring better pollination; with a successful transfer of pollen between flowers on the plants of a different species, it’s logical to assume that a cross would result.  However, cross-pollination rarely occurs in plants with flowers having both stamens and pistils. If it did, one might normally expect to find crosses between tomatoes, eggplants and potatoes–clearly, that doesn’t happen. Therefore it would be unlikely that a cross between a cherry tomato plant and a common climbing nightshade would be successful.

For further information please contact the Ontario Ministry of Agriculture, Food and Rural Affairs.  Their website, which includes contact information, is

This link to an article on the Ontario government website may be of interest.

All the best for your garden this summer. Thanks for contacting the Toronto Master Gardeners with your questions.