 So, all plants and animals have two sets of chromosomes. One comes from the male parent and one comes from the female parent. These chromosomes have to be kept in balance. Plants, unlike animals, have the ability to double all of their chromosomes. But of course, when this happens, and they are crossed to a normal plant again, instead of two sets, you now have three. This is bad because the three sets can no longer separate cleanly in the next generation. So plants have evolved a way in which they can count the chromosomes. This is not trivial. Chromosomes differ in DNA sequence, and it's very difficult to know how many there are. But all chromosomes are covered in transposable elements. And we've discovered a small RNA found in pollen that recognizes all transposable elements and therefore all chromosomes. And so this small RNA can count the number of chromosomes in the next generation. And this is important in evolution, but also in breeding, where breeders try to introduce chromosomes from species that have different numbers of chromosomes. By telling how plants count chromosomes, we can now enable this sort of breeding, understanding how they evolved.