People
often talk about regular leaf tomatoes or potato leaf tomatoes, I get a
few questions about this so I figured I would write a post explaining
what is meant by these terms. I have also seen one place sell a variety of tomato that they call "potato leaf tomato" and I find this confusing as there are many varieties of potato leaf tomatoes, I am growing 4 of them this year myself.
Have
a look at these two leaves, they are both leaves from tomato plants.
Please ignore the yellowing, that has nothing to do with leaf type, that leaf is a bit older.
Potato Leaf compared with Regular Leaf |
It
is not too difficult to tell them apart, the leaf on the left looks like the
leaf on a potato plant, the leaf on the right looks like the leaf on most
varieties of tomato.
Regular Leaf (RL) tomato |
Regular Leaf (often abbreviated RL)
This
is the typical leaf type that most people are familiar with, most
varieties of tomato are regular leaf. The leaf edges are serrated quite
a bit. There are a lot of variations on this basic theme in terms of the
width/length of leaf depending on the specific variety, climate
and growing methods. There are a few other variations such as angora, variegated
etc but they are not easy to come across in Australia so I wont talk about them. Some leaves are
very narrow and are sometimes called 'dissected', others are wispy or
droopy or look like the foliage of a carrot. These are easily recognised from a distance even by my 5 year old as the leaves of a tomato plant. All of this is referred to
as Regular Leaf (RL).
These
leaves usually have very few interruptions of the leaf edge. They are
fat and large leaves. Newly germinated seedlings sometimes don't show
their PL nature until they are a few inches tall, others show it as soon
as they grow their true leaves. PL leaves often have a thicker cuticle
than RL leaves or a higher density of trichomes (which are tiny little hairs on the leaf). Some claim that makes
them more tolerant of foliage diseases but I have seen no proof of
this. Leaf shape can be different on a single plant with some showing more or less smooth edges, all of this is normal for PL. Scientists
have divided the PL leaf forms into various different classes but few
of them are available in Australia and it makes no real difference so I wont write anything about them.
What is the deal with growing Potato Leaf tomatoes?
Some
people claim that potato leaf tomatoes taste better, unfortunately that
is a half truth. Almost all Potato Leaf tomatoes are heirlooms and generally
heirloom tomatoes taste great. Some tomato varieties have a Potato Leaf version
as well as a Regular Leaf version, I can not taste any difference.
People
often claim that Regular Leaf tomatoes do not cross pollinate while Potato Leaf tomatoes
will cross readily. Unfortunately this is not at all true. Most modern bred
varieties of tomato will not cross pollinate easily (literatures states
around 5% crossing without intervention when being grown side by side),
almost all heirloom tomatoes do cross pollinate, some far more than
others. As most Potato Leaf tomatoes are heirlooms people have got themselves
confused here. The tomato I grow that crosses most readily is
Reisetomate, it is a regular leaf plant. It cross pollinates so much that I even grow it in a separate garden to all my other tomatoes. Try not to be fooled, Potato Leaf does not necessarily mean heirloom, just as heirloom does not necessarily mean Potato Leaf.
Potato
Leaf is considered to be a recessive trait. When breeding new varieties if Potato Leaf is
crossed with Regular Leaf then all the seedlings will be Regular Leaf. This makes it useful
to see early on if the cross has worked or if the flower self
pollinated and the plant is worth growing on or not. If growing
different varieties of tomato then Potato Leaf can also indicate early on if that particular seed has remained pure. If a potato leaf variety grows regular leaf the chances are high that it has crossed. Some potato leaf varieties do occasionally throw a regular leaf plant even when they have not crossed, so things do get a little confusing here as there is a little more to it than a simple dominant/recessive trait.
"Julia Child" a great potato Leaf tomato variety |
I have
also heard anecdotal evidence that potato leaf varieties are more
'hungry' than regular leaf as they require more resources in order to build more
leaf, again I am yet to find any research that either backs or refutes this
claim. It kind of makes sense to me, but some of the largest tomato plants I have ever seen have been regular leaf, I assume they used a lot of resources to grow that large. I have one regular leaf tomato that grows a large shrub to about 8 feet in every direction, it is surely using a lot of resources to build all of that stem.
Some people think the Potato Leaf plants look nicer, I certainly think they look more ornamental and would not look out of place in a flower garden. To be honest, I wish that I had more potato leaf tomato varieties as I simply like the look of them.
At the end of the day though the leaf shape makes no real difference to me and I doubt it makes any real difference to taste, growth rates or anything other than aesthetics, so I base my planting decisions on the taste of the fruit and performance of the plant.