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Our mystery last week had to do with seeds.

mystery-tomato

The brown bumps on the outside of the tomato were the clue.

tomato-seeds-sprouting-inside

You might have been able to guess if I had shown you this view instead. Do you see the stems and green bits under the tomato skin?

tomato-seeds-sprouting-peeled

Peeling back the tomato covering, those are tomato seedlings sprouting inside the tomato fruit.

tomato-seeds-sprouting-opened

If you open it up to the center, you can see the seeds are sprouting from inside the tomato. It wasn't rotten or mushy at all. All the tomatoes in this cluster that I had purchased from the grocery store had sprouting seeds.

It turns out that it isn't all that uncommon for certain cultivars of tomatoes to do this, particularly the "tomatoes-on-the-vine" variety from the grocery store.

The first part of this video explains it is called vivipary when the seeds sprout inside the fruit, usually when still attached to the mother plant.

 

We also regularly see seeds sprouting inside our pink grapefruit towards the end of the season.

grapefruit-seed-sprouting-in-fruit

These are from fruit still hanging on the tree.

grapefruit-seed-sprouting-inside

Can you see the long root?

 

Have you ever opened a fruit and found a seed sprouting?

Katherine correctly identified our mystery seeds last week as tomato seeds. Good job!

You may not have identified them easily because fresh seeds are surrounded by a jelly-like goo. More about that in a minute.

The tomato above is Solanum lycopersicum (used to be called Lycopersicon lycopersicon). It is the common garden tomato, readily available in stores.

A few months ago a friend gave us some tomato plants she said were "honey pearls." They plants produced these lovely yellow/orange cherry tomato-sized fruit.

The plants continued to flower on and on through our excessively hot summer. Other varieties of tomatoes had always quit flowering during the summer.

In fact the plants are still producing tomatoes, even though we had always heard that tomatoes couldn't produce fruit if nighttime temperatures are too high. We wanted to learn more about them.

It turns out that these particular plants are a different species, Solanum pimpinellifolium, sometimes commonly called currant tomatoes.

Tomatoes were originally from South America. Currant tomatoes are one of the wild-type tomatoes that are edible. They are able to cross with garden tomatoes and some hybrid varieties exist. Isn't that amazing?

Now about the gel around the tomato seeds.

Evidence suggests that the gel around the tomato seeds (while they are in the fruit) prevents germination. Once the tomato fruit falls to the ground and rots, the gel breaks down and the tomato seed sprouts.

The CSIRO has a fun experiment with tomato seeds to test this.

I'm not completely convinced this is true for all tomato seeds. I have germinated seeds from fruit without fermenting them, although it is possible that the gel had broken down already for other reasons.You can be sure I'm going to be examining the question further.

Have you ever grown tomatoes from seeds? Were the seeds from seed packets or from seeds you saved?