Humans have two copies of each chromosome. Plants in nature can have many more, and some can be induced to duplicate their chromosomes which sometimes gives them larger seeds and resilience to environmental conditions. Similar to hybrid crops but somehow containing the full genomes of both parents. Bread wheat is hexapoloid (containing sub-genomes from three varieties of wheat) and quinoa is tetraploid (containing two different species). There have been projects for ~100 years to make polyploid rice with heavier grain-weight, but they haven't been able to reproduce.