Haleakala Silversword

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iHaleakala Silversword

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Asterales
Family:	Asteraceae
Genus:	Argyroxiphium
Species:	A. sandwicense
Subspecies:	macroencephalum

Trinomial name

Argyroxiphium sandwicense ssp. macroencephalum

The Haleakalā Silversword or Argyroxiphium sandwicense ssp. macroencephalum is part of the family Asteraceae. The silversword in general is referred to as 'Ahinahina' in Hawaiian (which literally means "gray gray", because when the native Hawaiian settlers first came to Maui, its silvery color had never before been seen by any of their ancestors and they therefore had nothing to compare the color to), and it has been a threatened species according to the U.S. Fish & Wildlife service since May 15, 1922. Excessive grazing by cattle and goats and vandalism inflicted by people in the 1920s caused near extinction of the Haleakalā Silversword. The plant has been strictly monitored and protected by the government since and is consequently a successful conservation story about the exotic plant life of the Hawaiian Islands. This plant is expressly found on the island of Maui in the Haleakalā National Park at an elevation of 2,100 to 3,000 m on the Haleakalā summit depression, the rim summits, and surrounding slopes of the dormant East Maui Volcano. Silversword plants in general grow on cinder, a magnetic-rich iron lava rock laden surface that is sparsely populated due to extreme conditions like freezing temperatures and high winds.

Before the National Park Service was granted control of Haleakalā volcano, visitors to the volcano's summit often participated in the common practice of uprooting a Haleakalā Silversword plant and then rolling it on the jagged lava rock terrain, drying the flowers for arrangements, or using the plant as kindling. Because the delicate, shallow root structure can be crushed by walking in the rocks around the plant severing the roots and the delicate skin is damaged by human touch the plant is very sensitive to foreign elements. 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. Although cattle and goat grazing destroys some plants, the human destruction was most detrimental. This depleted the species so much that eventually it became a threatened species after the Maui Chamber of Commerce successfully petitioned the federal government.

Haleakalā Silversword has numerous sword-like distinctively silver colored turgid leaves with silver hairs. The plant's base of leaves arranged in a spherical formation at ground level of the plant dominate for the majority of the plant's life which may be greater than fifty years. The leaves are arranged so that they and the hairs of the leaves can raise the temperature of the shoot tip leaves up to 20 °C to adapt to the extreme temperatures by focusing the sunlight to converge at this point and warm the plant. At senescence which often occurs when the plant reaches a diameter of approximately one-half meter, the plant produces a tall stalk of maroon ray flowers which resemble the sunflower in just a few weeks. Flowering usually occurs in June or July. This flowering stalk may have up to 600 heads of up to 40 outlying ray flowers and 600 disk flowers and is pollinated by flying insects like Hylaeus (Nesoprosopis) volcanica. The flower stalk can reach up to two meters in height and has numerous tiny sticky hairs to prevent crawling insects from damaging the plant. Seeding of the plant is very sensitive because damage to the flowers or stalk by insects before reseeding further hinders the threatened species’ propagation. Leaves become limp and dry as the plant seeds to secure the fate of a monocarp species.

To view the Federal Recovery plan of this threatened species and the other endangered species of Maui please visit the U.S. government's website file of the 1997 report of a Maui cluster of 21 taxa to recover at [1].