I heard when cross breeding there is a rare chance of getting a "mutant" wich is a uniquely colored plant that has no pollen or seeds. Is this true?
That is a very limited use of the word mutant. But yes, you can get that.
Hybrids with no pollen or seeds are common, when crossing species. Hybrids with unique color are also common in hybrids, interspecific or within a species.
But true mutations are more frequent in interspecific hybrids than in either parental species. This is due in part to chromosomes not pairing just right and breaking and re-fusing, with a loss or duplication fo a part of a chromosome. There are probably other mechinisms for mutating hybrids, this is just one.
I just attended a gardening class that explained mutations. The instructor talked about the work that was done years ago in a monistary that produced a 3 to 1 ratio for genes in peas. As in, if you cross tall pea with short peas you get some short and some tall--but no medium size. hyridizing is a seperation of genes, not a mixing of them. Hard to explain--but what he said about mutants--that cosmic energy which is picked up as ticks by a giger counter--and passes through everything because it is so small, needs to hit the nuculeus of a developing seed atom-which is 18,000 for the minus of a centimeter-to change its DNA. Or some people change DNA with chemicals. So even with us hybridizing, some things are just left to chance.
I have just been watching a TV programme which suggests that every human individual is a "mutant" from the norm. or average in some way or other. Surely the same is true of plants other than those created by vegetative propagation which are obviously biologically indistinguishable from their origin plant.?