Silversword alliance

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iSilversword alliance
Dubautia linearis
Dubautia linearis
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Asterales
Family: Asteraceae
Tribe: Heliantheae
Genera

Argyroxiphium
Dubautia
Wilkesia

"Silversword alliance" refers to a radiation of over 50 species in the composite or sunflower family (Asteraceae). The group is endemic to Hawaii, and is derived from a single immigrant to the islands.

The silversword alliance is named for its most famous and visually striking members, the silverswords. There are three species of silverswords and two greenswords in the genus Argyroxiphium, confined to the islands of Maui and Hawaii, and two species of Wilkesia (iliau) on Kauai. The bulk of the species are placed in the genus Dubautia, which is widespread on all the main islands.

Dubautia-silversword hybrid in Haleakalā Crater.
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Dubautia-silversword hybrid in Haleakalā Crater.

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.