Parker K. C., Hamrick J. L., Genetic diversity and clonal structure in a columnar cactus, Lophocereus schottii, American Journal of Botany, 1992, 79(1):86-96, doi: 10.1002/j.1537-2197.1992.tb12627.x
Examines eight Lophocereus schottii populations in Organ Pipe Cactus National Monument. Plant mapping and allozyme analysis identified 87 multilocus genotypes among 336 cacti. The authors discuss stem rooting, flood transport of fragments and the coexistence of clonal reproduction and genetic diversity.