This one is rarely known outside of plant breeding circles.
A sperm or egg cell has half the number of DNA strands and most examples are-- Haploid
A body cell for most plants and animals have a double DNA strand known as - Diploid
Less common examples have twice that number including certain varieties of wheat and potatoes known as Tetraploid as there are 4 DNA strands.
Prickly pears along with a few cultivated plants such as varieties of strawberries are again doubled and are known as octaploid-- having 8 DNA strands.
That means genetic mutations are less common making it hard to breed new varieties.