Hawaiian Silversword Alliance

Haleakalā Crater, Maui

Dubautia or Kupaoa, Na'ena'e

Or

Haleakelā Silversword

"ʻāhinahina"

Argyroxiphium sandwicense ssp. macrocephalum

Dubautia (cont.)

Haleakelā Silversword

"ʻāhinahina" (cont.)

Another genus that is part of the silversword alliance is the Dubautia. This genus contains most of the species of silversword relatives, which come in the form of shrubs, trees, or wooden vines.

The plant can live for about 40 to 50 years, in which it will only flower once, dying shortly after. The flowering spike can grow to be about 6 ft. 6in. and also may contain about 600 flowers.

Dubautia Retculata is endemic to East Maui. It is in the form of a large shrub or tree, which can grow to be up to 8m tall. They are found in wet forest habitats, at elevations ranging from 1500m to 2300m. Unfortunately, they are a threatened species due to habitat loss.

Some species from this genus are found on all major islands, and their habitats can range from low, wet elevations to high elevation and dry environments.

Haleakelā has a very arid, dry climate. This species of silversword has adapted to this by having succulent leaves, that contain air spaces with a viscous substance that allows the leaves to store water. The silver hairs on this plant provide insulation that protect it from heat and light that hit the 10,000 ft. mountain.

Dubautia menziesii

Damage caused by humans and destruction from grazing animals has resulted in this species of silversword to be listed as a threatened species by the U.S. Fish and Wildlife Service.

Argyroxiphium sandwicense ssp. macrocephalum [Online image]. Retrieved April 2016 from URL (http://agrowingobsession.com)

Carr, G.D. [Online image]. Retrieved April 2016 from URL (http://http://www.botany.hawaii.edu/)

Dubautia menziesii [Online image]. Retrieved April 2016 from URL (http://http://waynesword.palomar.edu/)

By Navin75 - Haleakala NPUploaded by Hike395, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=24963865

Kauai

Wilkesia

The last genus of the silversword alliance is Wilkesia. This genus contains two subspecies, Wilkesia gymnoxiphium and Wilkesia hobdyi. This genus is endemic to Kauai.

As you can see, Kauai has an wide array of silversword species, which could be caused by the fact that Kauai is the one of the oldest Hawaii islands. This means that since Kauai was perhaps one of the first islands that was colonized by the silversword ancestor, the ancestor may have radiated into many different subspecies on Kauai, and only a few of those subspecies had the chance to move to the younger islands, resulting in less species of silversword being found there.

Wilkesia gymnoxiphium or the ililau plant, commonly grow in Waimea Canyon; they can be found in dry to mesic forest zones and can grow to be 5m tall. A distinct characteristic is a flowering head that produces many daisy like flowers. The plant dies shortly after blooming.

Kauai is home to many species of silversword relatives from the genus of Dubautia. Examples include:

• Dubautia kalalauensis
• Dubautia imbricata
• Dubautia kenwoodii
• Dubautia knudsenii
• Dubautia laevigata
• Dubautia latifolia
• Dubautia laxa
• Dubautia microcephala
• Dubautia paleata
• Dubautia pauciflorula
• Dubautia plantaginea
• Dubautia raillardioides
• Dubautia syndetica
• Dubautia waialealae

By KarlM (talk) - I (KarlM (talk)) created this work entirely by myself., CC BY-SA 3.0, https://en.wikipedia.org/w/index.php?curid=25389162

Dubautia waialealae

Nielsen, J. [Online image]. Retrieved April 2016 from URL (http://http://www.flickr.com/)

Dubautia kalalauensis

Bainbridge, S. J. (2010). [Online image]. Retrieved April 2016 from URL (http://http://www.botany.hawaii.edu/)

Wilkesia hobdyi or the dwarf iliau, is a shrub that produces grass like leaves that sprout from the top of a short stalk. They can be found in dry, near vertical environments and flower mostly during the winter.

Medeiros A. C. [Online image]. Retrieved April 2016 from URL (http://http://www.botany.hawaii.edu/)

Vaughn, G. (2010). Waimea Canyon Iliau Plant [Online image]. Retrieved April 2016 from URL (http://http://www.fineartamerica.com/)

Mauna Kea, Hawai'i

Mauna Kea

Argyroxiphium sandwicense ssp. sandwicense

Subspecies of Dubautia only found on Hawai'i island:

An example of a species that is capable of living in such an unforgiving environment is a close relative of the Haleakelā silversword, the Mauna Kea silversword. This silversword is of the subspecies sandwicense. The two species differ on the morphology of their inflorescence, however they have some shared characteristics such as their succulent leaves for water storage and silvery hairs for heat and light reflection.

At about 13,800 ft. tall, Mauna Kea's climate is unfavorable for plants to thrive in. Factors that contribute to this mountain's harsh environment are the inversion cloud layer that separates the summit from the moist air below, keeping it dry, and the near freezing temperatures.

Dubautia ciliolata

Dubautia Arborea

[Online image]. Retrieved April 2016 from URL (http://luirig.altervista.org/)

Neilsen, J. [Online image]. Retrieved April 2016 from URL (http://http://www.flickr.com/)

Rownd, B. (2009). Dubautia Ciliolata Flowers [Online image]. Retrieved April 2016 from URL (http://http://www.pbase.com/)

Carr, G.D. [Online image]. Retrieved April 2016 from URL (http://www.botany.hawaii.edu/)

Tom[Online image]. Retrieved April 2016 from URL (http://apacificview.blogspot.com/)

[Online image]. Retrieved April 2016 from URL (http://theatlantic.com)

California

The silversword alliance has descended from a california tarweed ancestor that may have colonized the Hawaiian archipelago by various means, including having seeds stick to migratory birds, or by rafting their way to the islands. The silversword alliance is said to be one of the best examples of adaptive radiation, and is evident through the various species dispersed throughout the islands.

The similarties between the silversword alliance and the tarweed were discovered by researchers that studied the relationships of each species' chromosome number, organelle DNA, anatomy, and homeotic genes. There are three species of tarweed that are related to the silversword alliance, which include Carlquistia muirii , Anisocarpus scabridus and Kyhosia bolanderi.

Kyhosia bolanderi

Carlquistia muirii