Haplostachys haplostachya is probably the only one of the five Haplostachya species that is not now extinct, so it may be the only member of a monotypic genus. There are now fewer than 20,000 individual plants in scattered fragmented populations remaining at Kipukakalawamauna on the Pohakuloa Plateau, the site of the Pohakuloa Training Area. At one time, the plant was not uncommon on the slopes of Mauna Loa and Mauna Kea. Destruction of the habitat by feral ungulates, military construction, consequences of military activity such as dust and fires, introduced plant species, and deforestation have fragmented the plant's distribution and reduced it to its present low numbers. This fragmentation has also led to physical and reproductive isolation in the smaller, more isolated populations, causing a genetic bottleneck.