polyploid

Having more than two complete sets of chromosomes. Many plants that are polyploid, such as dandelions, are sterile but can reproduce by apomixis or other asexual means. Other polyploid plants are fertile. For example, durum wheat ( Triticum turgidum durum ), which is used to make pasta, is tetraploid (it has four sets of chromosomes), while bread wheat ( Triticum aestivum ) is hexaploid (six sets of chromosomes). Polyploid plants, if viable, are often larger or more productive than diploid plants, and plant breeders often deliberately produce such plants by crossing species or other means. In the animal kingdom, polyploidy is abnormal and often fatal.