There are 2 different charts, one which has the plant species charted, and one that has the different flower combinations possible. If you know what kind of plant you want to create, check inside the plant chart until you find it. Follow the row across, and the column up to the headers until you locate the two plants you need to start with. (Sometimes, you have to search for other possibilities until you find a combination with plants that you already have

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Using the example of the maple ... (We already know what 2 plants we need, so we're ahead here) Look along the top row of the plants chart until you find the location of the maranta, or the ball cactus. Then look down the side until you find the other plant of the two. Now follow inside the chart until you locate where the two meet. You should see Maple listed at the junction.
When you want to create something new you just reverse that process, and locate the plant you want to create in the main body of the chart, then follow the row out, and the column up until you find the 2 needed plants (one along the left side, and one along the top).
For the type of flower (in this case, Citrus), if you breed two different plants both with the same type of flower, you'll get that same type of flower in your new seed (so, in this case, you don't need to even look at the other chart). Then, after you've pollenated your plants, planted and sprouted your new seed, and waited for it to mature, you should have the plant you wanted.
I hope that that actually helped, and not just confused you even more.
