The zygoid state of a species may be diploid or polyploid. Similarly, homoploid speciation contrasts with polyploid speciation. About 70% of angiosperm species have endosperm cells that are polyploid. This results in polyploid cells or, if the chromosomes duplicates repeatedly, polytene chromosomes. It is possible for polyploid organisms to revert to lower ploidy by haploidisation. The species is polyploid (having more than two sets of chromosomes). There are few naturally occurring polyploid conifers. Colchicine is also used in plant breeding to produce polyploid strains. With polyploid hybridization, this constraint is less acute. "Opuntia ficus-indica" is polyploid, hermaphrodite and autogamous. Chromosome numbers include 2n=14, 22, 26, with numerous aneuploid and polyploid derivatives. The creation of polyploid species results from natural random events tolerated by polyploid-capable plants. Rare instances of polyploid mammals are known, but most often result in prenatal death. In polyploid obligate parthenogens like the whiptail lizard, all the offspring are female.