Haleakalâ silversword shrub up close
Haleakalâ silversword (Argyroxiphium sandwicense macrocephalum) ('âhinahina ("very gray") in Hawaiian)
Belonging to the sunflower family, this plant is endemic to Hawaii. It is only found on the island of Maui in Haleakalâ National Park at an elevation of 2,100 to 3,000 m on the Haleakalâ summit depression, the rim summits, and surrounding slopes of the dormant Haleakalâ volcano. Silversword plants in general grow on volcanic cinder, a dry, rocky substrate that is subject to freezing temperatures and high winds. The skin and hairs are strong enough to resist the wind and freezing temperature of this altitude and protect the plant from dehydration and the sun. They are adaptated to low-nutrient soils.
A rosette-forming shrub will grow 15-50 years before flowering only once (usually in June or July), after which it dies. The flowering stalk can reach up to two meters in height, and may have up to 600 maroon sunflowerlike flower heads. Because they require cross pollination by insects, many plants must flower at the same time in relatively close proximity or they will fail to set seed. A significant population must exist for enough to flower each year for pollination to occur.
Silverswords are highly sensitive to disturbance. The plant was near extinction in the 1920's because of human vandalism and browsing by goats and cattle. Currently listed as a vulnerable species (likely to become endangered) on the IUCN Red List it is at the same time considered a successful conservation story.