There are many (many) different varieties tomatoes. I have seen the figure 6,000 quoted and in some respects I feel this is possibly an underestimate.
Tomatoes have two conflicting habits. On the one hand they cross easily (hence the large number of different varieties). On the other they are self-fertile and most varieties are unlikely to get fertilised by another tomato plant unless something deliberate happens (like mankind interfering). Seeds collected from tomatoes that have been grown and not deliberately crossed are called “open pollinated” and will normally breed true. Tomato varieties which have been grown in this way for more than a number of years (usually 50) are known as Heritage tomatoes (in Britain) or Heirloom tomatoes in America. Being flexible, we use both phrases interchangeably.
What all this means is that when you grow heritage tomatoes, you can usually guarantee that the seeds taken from a tomato on a plant will grow the same tomato next year. If you take seeds from an indeterminate, red, potato leafed Bloody Butcher tomato this year, and sow them next year, there’s a strong probability that what you will grow will be an indeterminate, red, potato leafed tomato with the same flavour as Bloody Butcher.
Hybrid tomatoes are commercially created by taking two parent plants which exhibit particular desirable characteristics and deliberately cross-fertilising them in the hope/expectation that the good characteristics of the parent plants will re-enforce each other in the offspring. It is unlikely that seeds taken from the offspring of a hybrid tomato will breed-true.
If you take the seeds from an indeterminate, orange, regular leafed Sungold tomato (an F1 Hybrid), you will get a range of different plants, many of them throwbacks to the original parents but others which will be new varieties again.
However, many Heritage tomatoes have been deliberately created by creating a new hybrid and then sowing the seeds year after year, keeping the plants which exhibit the desired characteristics and doing this time and time again until the plant breeds true. (Anecdotally it seems that this takes about seven years). If the plant remain popular and is grown for many years, it becomes an Heirloom tomato by virtue of being grown for over 50 years. One classic example of this is that, in the 1940s, Marshall Cletis Byles created what he considered the best tomato in the world in precisely this way and Mortgage Lifter is a popular tomato to this day (and one that we grow).
Family/Commercial Heirloom Tomatoes
There are a number of Heritage tomatoes, which have been maintained by a family or small group of people, these are known as “Family Heirlooms” rather than the “Commercial Heirlooms” which are available from seed suppliers. These are decreasing in number as they are sent to commercial seed producers to be added to the long list of tomato varieties.
Open Pollinated Tomatoes
Finally, between the F1 Hybrid and the Heirloom are the “Open Pollinated” tomatoes. A variety which grows true from its parent but which hasn’t been continuously grown for 50 years or more is “Open Pollinated“. An example we have of this is “Oleron Yellow”. This was given to us “by mistake” and, whilst we can find a few references to in on the web, we can’t find anybody who can supply seeds. As a result, we don’t know how long it has been grown and don’t consider it to be a true Heritage tomato.
Identifying Tomatoes
There doesn’t seem to be a “wordwide catalogue” of tomatoes. Nor even a standard way of determining the variety of a tomato. If you keep your own seed and grow it on, its impossible to prove that the variety hasn’t changed, it may look the same and even taste the same but it might not be genetically identical to its original parent.
Similarly just because two tomatoes have different names doesn’t mean they aren’t the same (in fact there seems to be a deliberate policy to give tomatoes different names in Europe and the US and translations from a common – difficult – language such as Russian, frequently leads to multiple names. We had this with Matina and Tamina which are the same tomato from two different sides of the Atlantic.
Why grow Heirloom/Heritage Tomatoes?
We choose to grow Heirloom or Heritage tomatoes in preference to F1 hybrids because:
- We think they taste nicer;
- There’s a wide choice of varieties (without struggling we can find suppliers of over 600 different heritage varieties);
- We can grow the same varieties every year (many hybrids seem to be “fashionable” and come and go when they don’t sell well);
- Nobody is promoting the Heritage tomato, making a living out of advertising and selling the seeds/plants;
- Heritage varieties have survived because they are liked, not because a major seed producer wants us to like them;
- We can save our own seed if we want to and grow them in following years.
Genetic Modification and Tomatoes
There is a lot of debate about Genetically Modified vegetables in general, and you may be pleased to know that, at the moment, there are no genetically modified tomatoes on the market.
Proponents of genetic modification would claim that genetic modification is no different to the breeding programmes that take place creating Hybrid tomatoes (and new varieties of Heirloom tomatoes in the long term).
There were two experiment in genetic modification of tomatoes, both of which failed for different reasons (See here for more information). However, the result of these failed experiments is that commercially harvested tomatoes still don’t have the flavour of heirloom or open pollinated varieties grown yourself.