Photo by Melody

PlantFiles: Ahinahina, Haleakala Silversword
Argyroxiphium sandwicense subsp. macrocephalum

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Family: Asteraceae (ass-ter-AY-see-ee) (Info)
Genus: Argyroxiphium (ar-gy-roh-ZIF-ee-um) (Info)
Species: sandwicense subsp. macrocephalum

3 members have or want this plant for trade.

Category:
Perennials
Shrubs

Height:
18-24 in. (45-60 cm)
24-36 in. (60-90 cm)
8-10 ft. (2.4-3 m)

Spacing:
18-24 in. (45-60 cm)
24-36 in. (60-90 cm)
36-48 in. (90-120 cm)

Hardiness:
Not Applicable

Sun Exposure:
Full Sun

Danger:
N/A

Bloom Color:
Pink
Purple

Bloom Time:
Mid Summer
Late Summer/Early Fall
Mid Fall
Late Fall/Early Winter

Foliage:
Silver/Gray
Velvet/Fuzzy-Textured

Other details:
This plant may be considered a protected species; check before digging or gathering seeds

Soil pH requirements:
Unknown - Tell us

Patent Information:
Unknown - Tell us

Propagation Methods:
From seed; direct sow outdoors in fall

Seed Collecting:
Bag seedheads to capture ripening seed

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to view:

By Equilibrium
Thumbnail #1 of Argyroxiphium sandwicense subsp. macrocephalum by Equilibrium

By Equilibrium
Thumbnail #2 of Argyroxiphium sandwicense subsp. macrocephalum by Equilibrium

By Equilibrium
Thumbnail #3 of Argyroxiphium sandwicense subsp. macrocephalum by Equilibrium

By ilima
Thumbnail #4 of Argyroxiphium sandwicense subsp. macrocephalum by ilima

By ilima
Thumbnail #5 of Argyroxiphium sandwicense subsp. macrocephalum by ilima

By ilima
Thumbnail #6 of Argyroxiphium sandwicense subsp. macrocephalum by ilima

By GreenEyedGuru
Thumbnail #7 of Argyroxiphium sandwicense subsp. macrocephalum by GreenEyedGuru

Profile:

3 positives
No neutrals
No negatives

Gardeners' Notes:

RatingAuthorContent
Positive kaulanaH On Jul 15, 2010, kaulanaH from Kamuela, HI wrote:

i apologize for my mistake, im new to "daves garden" but i do live in hawaii, n i kno just about all of our endemic plants, if your looking for ahinahina you wont find it elsewhere, keep in mind that there are atleast five that i can think of at the moment species of ahinahina, all of which are protected by state AND FEDERAL LAW ANYONE WHO TAKES ANY PLANT MATERIAL ie:seeds, flowers, small plants. FROM THESE SPECIES ARE BREAKING STATE AND FEDERAL LAWS.
anywho...:) it is also one of my favorites, silverswords are endagered and for them to thrive in the wild plants must cross pollinate, if not the plant will produce in-viable seed which are bourne upon achnes.

Positive foodiesleuth On Feb 27, 2005, foodiesleuth from Honomu, HI (Zone 11) wrote:


`Ahinahina (Hawai`i’s native silversword plant) is noted for its silvery radiance and sharp spiky ball shape. The silver hairs on its rigid sword-like leaves help prevent it from burning as it reflects ultra-violet light and also help the plant to capture moisture from the morning dew.

There are three species of silversword, found on the slopes of Mauna Kea, Mauna Loa (on the Big Island of Hawaii) and Haleakala on Maui. It is believed that the silversword is a distant relative of a California Tarweed which made it to Hawai`i on its own and over many centuries has evolved into the unique plant we see today.

Upon maturity after twelve to fifty years, the silversword will produce a five-foot-tall stalk from its center covered with hundreds of one-inch flowers, produce seeds for the next generation, and die.

Since the 1700’s, upon European colonization, the silversword population has declined due to several factors. Human vandalism decreased the abundant population, when people picked the plant and also thought it was amusing to kick the silversword down the mountain like a soccer ball. Browsing and trampling by feral sheep, goats and mouflon sheep introduced to Hawai`i for sport hunting has also affected the population. Loss of native pollinators (moths and bees) due to introductions of alien insects (wasps and ants) is currently limiting the silversword reproduction rate.

There are efforts being made by scientists to protect the remaining population and increase their numbers. Fear that natural pollination will not keep the species alive has left biologists pollinating the plants by hand. Also, when the silversword produces seeds, they are collected and propagated in a nursery. When a large number of seedlings are available, then they are outplanted back into the wild.

“Between 2000-2002 there were almost 7,000 seedlings planted on Mauna Loa,” said Tim Tunison, Chief of Resources Management, Hawai`i Volcanoes National Park. “And these plants have had a 90% success rate!” There have also been outplantings on Mauna Kea and Haleakala. Hopefully, there will be continued success in silversword outplantings, which will increase our chances of catching a glimpse of this unique endangered species!

From an article:
90% Success Rate for Mauna Loa Silversword Planting!
Article by Kuhea Paracuelles and Lauren Danner

foodiesleuth's note: at the 9,000 ft elevation of Mauna Kea, near the Onizuka Visitor Center, Park Rangers have fenced in an area where several silverswords have been found.

Positive Equilibrium On Feb 26, 2005, Equilibrium wrote:

I rate this plant a positive for its rareness however growing it isn't going to happen for you unless you live at an elevation greater than 6,500'.

There are two recognized subspecies of Argyroxiphium sandwicense; A. sandwicense subsp. macrocephalum has a more elliptical-looking inflorescence than A. s. subsp. sandwicense, which is thicker. Native to Hawaii, Argyroxiphium sandwicense subsp. macrocephalum is found only on the island of Maui up on the Haleakala volcano in and around the crater at elevations greater than 6,500’. The plant will only flower once in its lifetime which is around 20 years. The flowers will appear mid summer to early winter. After the seeds disperse, the whole plant dies. Their cultural requirements (the plant will not survive at lower elevations) are such that in an attempt to conserve this species, a high altitude rare plant facility has recently been built. The Silversword plant is well suited to its harsh environment in that the silver leaves reflect the sun's rays and its compact shape prevents moisture loss and protects the more delicate center of the plant from predation. It has a large taproot that helps to anchor it to better withstand the high winds of its alpine cinder desert habitat. The leaves are narrow and stiff, sword shaped, and are covered with silky/silver hairs. When the plant flowers, it can attain heights of 9’ otherwise it grows to about 2’ in its non flowering shrub form.

This subspecies is endemic to East Maui and is listed as Threatened under the U.S. Endangered Species Act. A major threat to this plant continues to be people who climb the mountain and dig it up as a souvenir to prove they made it to the top. Additionally, hikers who walk near the plant inadvertently sever the roots when stepping on sharp cinders in and around the plants so if you visit the site it is best to not walk anywhere near the Silverswords. Other major threats are introduced goats, pigs, and cattle that browsed and trampled them prior to the construction of exclusion fencing. The A. sandwicense is quite vulnerable. Currently, the single greatest threat to the survival of this species, as noted by Maui Bicycle Safaris, LTD would be-
“A close-up of an 'ahinahina blossom reveals lots of little flower that look similar to a sunflower. The 'ahinahina is a member of the sunflower family, whose flower heads are actually made up of several hundred disc and ray flower. 'Ahinahina cannot produce fertile seeds without cross-pollination. Therefore, these plants are dependent upon insect pollinator for long-term survival. Native moths, flies or bees travel in a circle around the perimeter of the blossom gathering pollen. Cross-pollination occur when the insect travels to the blossom of another 'ahinahina plant. The introduction of foreign insects, such as the Argentine ant, that prey on the native pollinator could result in a dramatic decrease in 'ahinahina populations.”

As noted by Emily Butler, “The silversword is a plant that has made incredible adaptations in order to be successful in extreme environments. The silversword is found at heights of seven thousand to ten thousand feet on the Haleakala Crater on the island of Maui. In the Haleakala Crater the silverswords are found on cinder cones. Conditions in this crater would be fatal to most other plants. It is extremely dry in the crater. Temperatures drop below freezing at night, and the sun is extremely harsh during the day. During the winter months it sometimes snows, although precipitation as rain or snow is small. A silversword can live as long as twenty years. When it reaches a diameter of two feet it produces an incredible flower stalk that can grow to be up to six feet tall or more. After the production of this flower the silversword dies. The silversword shows many adaptations to the harsh conditions presented by the Haleakala Crater in which is lives. The silversword lies low to the ground, and its growing point is buried inside the globe of its silvery leaves. The growing point is buried here so that it is protected from the cold. Like many desert plants, the silversword has very narrow leaves that serve to keep it from drying up from the heat of the sun. Narrow leaves protect it from the drying effects of the wind as well. The small surface area of the leaves minimizes and prevents water loss. Inside its leaves the silversword has a jelly or gelatinous substance, whereas most plants have several small air spaces. This jelly-like substance serves to store water for when it is extremely hot and there is no precipitation. The hairs on the leaves of the silversword represent another of the silverswords many adaptations to difficult conditions. The hairs on its leaves are flat and concave, as opposed to being round or convex. Because they are flat and concave the hairs act to reflect light from the leaves instead of focusing it on the leaves. The silversword is yet another great example of an organism exploiting an extreme ecological niche in a limited and easily defined geographic area.”



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