The Mauna Kea silversword (Argyroxiphium sandwicense ssp. sandwicense), is a giant rosette plant endemic to the alpine areas of Mauna Kea volcano on Big Island.
Individual plants live from three to over 50 years and produce flowers only ones in their lives. After flowering, the entire plant dies.
The Mauna Kea silversword may have been abundant once on Mauna Kea alpine regions between 2,600 to 3,800 meter elevations. The decline and almost extinction of these plants can be attributed to cattle grazing – sheep and goats particularly.
In the 1790s, humans introduced cattle, sheep, goats, dogs and pigs to Hawaii. Both domestic and feral animals were fed on native plants. This reduced the thriving population of silverswords to a few individuals. And in less than 30 years, it put them on a brink of extinction.
Currently, the wild species has been reduced to a single naturally occurring population in Waipahoehoe Gulch.
The Hawai‘i Department of Land and Natural Resources Division of Forestry and Wildlife has been actively involved in the preservation and restoration of the Mauna Kea silversword. In early 1980s, they collected and out planted silverswords in three enclosures within in the Mauna Kea Forest Reserve. One such place is a small silversword garden near the Mauna Kea Visitor Information Station. In this garden, each plant has its own number. There is a short trail that leads from the Visitor Center to the garden and inside, where you can walk and see the plants.
There are only five populations of silverswords on Mauna Kea and in a nearby region, which account for only ~ 8000 plants. And only one is a natural wild population, which has ~ 20 plants. The rest are human created and supported.
In 1999, more than 2500 additional silverswords were planted on Mauna Kea at multiple protected sites. Unfortunately, because they flower only once in life, no additional wild flowering occurred until 2005. In September 2005, 100,000 seeds were collected from hand pollinated crosses of a wild individual with several outplanted individuals.
The rate of successful reintroductions gives hope that this species might be brought back from the brink of extinction.