''Opuntia diploursina'' is a species in the family

Cactaceae A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...

, that grows near and in

Lake Mead National Recreation Area Lake Mead National Recreation Area is a U.S. national recreation area in southeastern Nevada and northwestern Arizona. Operated by the National Park Service, Lake Mead NRA follows the Colorado River corridor from the westernmost boundary of Gran ...

and northward across Nevada's Mormon Mesa, into Utah. This species is a close relative and probable ancestor of ''Opuntia erinacea'', but "...differs in minor spines more closely appressed to pad surface, spines smaller in diameter and more flexible, inter-areolar distance less, upright growth habit, larger fruit with longer, more flexible spines, larger seeds, and diploid chromosome number (2n=22)". ''Opuntia diploursina'' is also related to another diploid species, ''O. trichophora'', but differs from that species, as stated in the original description, in more upright growth habit, more minor spines that are more closely appressed to pad surface, closer spaced areoles, often yellow spine color as opposed to white or gray mature spines;; more and longer spines on fruit. ''O. diploursina'' also has curling major spines, and larger fruit. The two species are separated by hundreds of miles. ''Opuntia diploursina'' (2n=22) is known to hybridize with ''O. basilaris'' (2n=22) wherever the species co-occur. This results in fertile progeny that can backcross with either parent eventually creating a

hybrid swarm A hybrid swarm is a population of hybrids that has survived beyond the initial hybrid generation, with interbreeding between hybrid individuals and backcrossing with its parent types. Such population are highly variable, with the genetic and phe ...

. The

polyploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...

''O. erinacea'' (2n=44) which is widely distributed in the Mojave and Great Basin deserts, is suspected to be a stabilized allopolyploid derived from ''O. diploursina'' and ''O. basilaris''. Some ''O. diploursina'' x ''basilaris'' progeny resemble ''O. basilaris'' var. ''treleasei'' (2n=33), an endemic species of California.Beckstrom, M., Stock, A. D., Ginkel, C., & Hussey, N. (2014). Diploid Opuntia Hybrids from Northwestern Arizona. Cactus and Succulent Journal, 86(4), 165-171.

References

External links

Opuntia diploursina description and photo gallery at Intermountain Region Herbarium NetworkOpuntia diploursina description and photo gallery at SEINet Arizona – New Mexico ChapterOpuntia diploursina photo gallery at Opuntia Web
diploursina Cacti of the United States {{Cactus-stub