Although the Hawaiian name for this plant is not historically known, it is often referred to today as ‘Āhinahina, Hinahina or Hinahina Ewa. The reason for these names primarily has to do with their color. In Hawaii, many plants that are silvery in color are called hinahina or have the word hinahina in its name. (Hui Ku Maoli Ola)
Āhinahina (very gray) is the product of evolution in island isolation. Several million years ago, a California tarweed seed traveled 2,000 miles across the Pacific to Hawaii.
This single species evolved into the “silversword alliance,” a group of more than 30 species endemic to Hawai‘i that range from scraggly shrubs to ground-clinging cushions. (NPCA)
It is a distinctive, globe-shaped rosette plant, with a dense covering of silver hairs. (FWS) We commonly call this plant the Silversword (due to their long, slender leaves and a silver-white color).
After 10 to 30 years of rosette growth, thousands of aromatic flowers erupt from a human-sized stalk and are pollinated by native Hylaeus bees. After the silversword has finished flowering, it will die (silverswords only flower once in a lifetime). (NPS)
Some of the notable āhinahina are named for the mountains where they are found: Haleakalā Silverswords, Mauna Loa Silverswords, and Mauna Loa Silverswords.
Haleakalā Silverswords from Maui has larger flowers than the form on the island of Hawaiʻi. These plants were formerly abundant, but earlier in the century they faced the brink of extinction due to habitat destruction, goat grazing, and insect infestations.
Hotter temperatures and lower rainfall presents a new threat to these charismatic plants. Researchers with the University of Hawai‘i are actively working with park staff to evaluate the effects of drought conditions on Silverswords, and preserve these unique plants for generations to come. (NPS)
Haleakalā Silverswords live only in a 2,500-acre area at the top of the Haleakalā volcano, a moonscape pocked by cinder cones. They have developed an adaptation to cope with this harsh environment: The fleshy leaves are coated with tiny silvery hairs to break the wind, prevent drying and collect cloud moisture. (NCPA)
Mauna Kea Silverswords produce pink to wine-red flowers is rare and only found in the alpine regions of Mauna Kea. The harsh and challenging conditions of Mauna Kea volcano have forced the Silverswords to adapt to the environment in unique ways, similar to Mauna Loa Silverswords.
Leaves are covered with a dense layer of tiny hairs that help reflect sunlight and insulate the plant against cold temperatures. Sadly, impacts of climate change, and foraging invasive animals have put Silverswords in danger.
There are no records of the extent or density of the Mauna Kea silversword population prior to the introduction of ungulates to the island of Hawai’i in 1793 and 1794.
The Mauna Kea Silversword may have already been in decline due to browsing by feral ungulates by the time the silversword was first collected by James Macrae in 1825. Macrae noted in his diary that he found the remains of dead sheep near the summit of Mauna Kea on the same day that he encountered the silversword. (Mauna Kea Silversword Recovery Plan)
The Mauna Kea Silversword is distinguished from the Haleakalā Silversword by a high frequency of branching; taller, thinner flowerings; green bracts subtending flower heads; and fewer ray florets. (Mauna Kea Silversword Recovery Plan)
Mauna Loa Silverswords are perhaps lesser known than its Haleakalā and Mauna Kea cousins. The Kaʻū silversword is one of two forms of the Mauna Loa silversword that grow exclusively on Mauna Loa volcano.
The other, the Waiākea silversword, is rarer and found in wet bog habitat. Like its cousins, the Kaʻū form is in the sunflower family and blooms once by sending forth a dramatic stalk of small fragrant sunflower-like blossoms from its center.
These blooming stalks can reach nine feet in height. The plant dies after its towering display, but releases thousands of seeds to continue its legacy. (NPS)
The Mauna Kea Silversword probably only occurred on Mauna Kea. However, there are some historical and recent suggestions that a similar taxon may have occurred on Hualālai and on Mauna Loa.
The Mauna Kea Silverswords was first collected by James Macrae in 1825. Macrae’s specimens were sent to Augustin-Pyramus DeCandolle in Geneva. Later, David Douglas collected the Mauna Kea silversword in 1834 and sent specimens to WJ Hooker at Kew Gardens.
In 1852, Asa Gray described the Haleakala Silversword as endemic to the island of Maui. The similarity in vegetative features between Mauna Kea Silversword and the Haleakalā Silversword has led several authors to consider these taxa as the same species. (Mauna Kea Silversword Recovery Plan)
In 1875, world traveler Isabella Bird, in Haleakalā, stated, “Soon after noon we began to descend; and in a hollow of the mountain, not far from the ragged edge of the crater, then filled up with billows of cloud …”
“… we came upon what we were searching for; not, however, one or two, but thousands of silverswords, their cold, frosted silver gleam making the hill-side look like winter or moonlight.” (Bird, Six Months)
Alexander noted in his Ascent of Mauna Kea, in 1892, “We crossed a shallow crater just east of a conspicuous peak called “Ka lepe a moa”, or cock’s comb, and began to ascend the mountain proper. After climbing a steep ridge through loose scoria and sand, the party halted for lunch at an elevation of 10,500 feet.”
“The upper limit of the māmane tree is not far from 10,000 feet. … The beautiful Silver Sword (Argyroxiphium), once so abundant is nearly extinct, except in the most rugged and inaccessible localities.” (Alexander, PCA, Sep 14, 1892)
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