Mauna Kea Silversword

The Hawaiian Islands are sometimes known as the "endangered species capital of the world" for the state's large number of unique plant and animal species classified as threatened or endangered.

One of the more spectacular examples is the Mauna Kea silversword (Argyroxiphium sandwicense ssp. sandwicense). This plant is named for its mountain habitat, the Mauna Kea volcano on the Big Island, and for its striking rosette of dagger-shaped leaves covered with dense layers of silvery hairs.

It blooms once, producing a massive 6-foot-tall flowering stalk with up to 600 showy heads, each containing up to 500 individual flowers. Its impressive appearance is matched by its vulnerability.

When European voyagers arrived in the 1790s, they introduced sheep and other non-native ungulates to Hawaii, with devastating impacts on native plants. The ungulates, which rapidly multiplied, browsed the plants heavily and disturbed fragile habitats. By the 1970s, only a small population of Hawaiian silverswords remained, confined mainly to cliffs and sheer rock faces that ungulates could not reach. Early recovery efforts involved growing silverswords in cultivation and transplanting them into fenced areas, but this unintentionally led to a genetic bottleneck and reduced seed viability. Now, recovery includes genetic management; researchers often dangle precariously over cliffs to gather pollen from the wild plants to hand-pollinate nursery-produced specimens.

Among the partners in the Mauna Kea silversword recovery and management program are the Fish and Wildlife Service, National Park Service, U.S. Geological Survey, Hawaii Division of Forestry and Wildlife, University of Hawaii (including its Volcano Rare Plant Propagation Facility), Ranch Santa Ana Botanic Garden, Claremont Graduate University, University of Arizona, and the Hawaiian Silversword Foundation.