Factors Affecting Seed Germination of the Mauna Kea Silversword in Hawai'i

Abstract

The Mauna Kea silversword, Argyroxiphium sandwicense DC, is endemic to the slopes of Mauna Kea on the island of Hawai'i. Once abundant, it is now reduced to a total of less than 500 individuals. We examined germination of silversword seeds subjected to various experimental and field conditions. Under experimental conditions, germination was optimal in moist, shady environments. Removal of the pericarp greatly enhanced germination, but cold and heat pretreatments did not alter germination. Germination of field-collected seeds was highest for seeds < 2 yr old and for seeds collected from flower stalks. The ability to germinate was much lower for seeds collected from on or under the soil surface. In mesic environments, grasses competed with silversword seedlings. We suggest that seed germination and early seedling establishment are major obstacles to reestablishment of the Mauna Kea silversword.