Silversword alliance refers to an adaptive radiation

Adaptive radiation

In evolutionary biology, adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. Starting with a recent single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different...

 of over 50 species in the composite or sunflower

Sunflower

Sunflower is an annual plant native to the Americas. It possesses a large inflorescence . The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun. The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads...

 family, Asteraceae

Asteraceae

The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...

. The group is endemic to Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

, and is derived from a single immigrant to the islands. For radiating from a common ancestor at an estimated 5.2±0.8 Ma, the clade is extremely diverse, composed of trees, shrubs, subshrubs, mat-plants, cushion plants, rosette plants, and lianas.

The silversword alliance is named for its most famous and visually striking members, the silverswords

Argyroxiphium

Argyroxiphium is a small genus of five species in the sunflower family, Asteraceae. Its members are known by the common name of silversword or greensword due to their long, narrow leaves and the silvery hairs on some species. It belongs to a larger radiation of over 50 species, including the...

. There are three species of silverswords and two greenswords in the genus Argyroxiphium

Argyroxiphium

Argyroxiphium is a small genus of five species in the sunflower family, Asteraceae. Its members are known by the common name of silversword or greensword due to their long, narrow leaves and the silvery hairs on some species. It belongs to a larger radiation of over 50 species, including the...

, confined to the islands of Maui

Maui

The island of Maui is the second-largest of the Hawaiian Islands at and is the 17th largest island in the United States. Maui is part of the state of Hawaii and is the largest of Maui County's four islands, bigger than Lānai, Kahoolawe, and Molokai. In 2010, Maui had a population of 144,444,...

 and Hawaii

Hawaii (island)

The Island of Hawaii, also called the Big Island or Hawaii Island , is a volcanic island in the North Pacific Ocean...

, and two species of Wilkesia

Wilkesia

Wilkesia is a genus of flowering plants in the daisy family, Asteraceae. It contains two perennials, both of which are endemic to the island of Kauai in Hawaii. Wilkesia is a component of the silversword alliance.-Species:...

(iliau) on Kauai

Kauai

Kauai or Kauai, known as Tauai in the ancient Kaua'i dialect, is geologically the oldest of the main Hawaiian Islands. With an area of , it is the fourth largest of the main islands in the Hawaiian archipelago, and the 21st largest island in the United States. Known also as the "Garden Isle",...

. The bulk of the species are placed in the genus Dubautia

Dubautia

Dubautia is a genus of flowering plant in the sunflower family, Asteraceae, that is endemic to Hawaii. It contains more species than the other two genera in the silversword alliance, including cushion plants, shrubs, trees, and lianas.-Selected species:...

, which is widespread on all the main islands.

The genus Dubautia contains a wide variety of life-forms, including cushion plant

Cushion plant

A cushion plant is a compact, low growing, mat forming plant that is found in alpine, subalpine, arctic, or subarctic environments around the world...

s, shrubs, trees, and liana

Liana

A liana is any of various long-stemmed, woody vines that are rooted in the soil at ground level and use trees, as well as other means of vertical support, to climb up to the canopy to get access to well-lit areas of the forest. Lianas are especially characteristic of tropical moist deciduous...

s.

Similar species frequently occur in the same habitat and are often difficult to tell apart. Hybrids frequently occur between Dubautia species, and between Dubautia and Argyroxiphium. As a result, there is some disagreement over the number of species.