Located about 2300 miles (3680 km) from the nearest continental shore, the Hawaiian Islands are the most isolated group of islands on the planet. The plant and animal life of the Hawaiian archipelago is the result of early, very infrequent colonizations of arriving species and the slow evolution of those species—in isolation from the rest of the world's flora and fauna—over a period of at least 5 million years. As a consequence, Hawai'i is home to a large number of endemic species. The radiation of species described by Charles Darwin in the Galapagos Islands which was critical to the formulation of his theory of evolution is far exceeded in the more isolated Hawaiian Islands.
Hawaiian hibiscus are seven species of hibiscus native to Hawaii. The yellow hibiscus is Hawaii's state flower. Most commonly grown as ornamental plants in the Hawaiian Islands are the non-native Chinese hibiscus and its numerous hybrids, though the native Hibiscus arnottianus is occasionally planted.
Argyroxiphium is a small genus of plants in the family Asteraceae. Its members are known by the common names silversword or greensword due to their long, narrow leaves and the silvery hairs on some species. The silverswords belong to a larger radiation of over 50 species, including the physically different genera Dubautia and Wilkesia. This grouping is often referred to as the silversword alliance. Botanist P. H. Raven referred to this radiation as "the best example of adaptive radiation in plants".
The Hawaiian tropical rainforests are a tropical moist broadleaf forest ecoregion in the Hawaiian Islands. They cover an area of 6,700 km2 (2,600 sq mi) in the windward lowlands and montane regions of the islands. Coastal mesic forests are found at elevations from sea level to 300 m (980 ft). Mixed mesic forests occur at elevations of 750 to 1,250 m, while wet forests are found from 1,250 to 1,700 m. Moist bogs and shrublands exist on montane plateaus and depressions. For the 28 million years of existence of the Hawaiian Islands, they have been isolated from the rest of the world by vast stretches of the Pacific Ocean, and this isolation has resulted in the evolution of an incredible diversity of endemic species, including fungi, mosses, snails, birds, and other wildlife. In the lush, moist forests high in the mountains, trees are draped with vines, orchids, ferns, and mosses. This ecoregion includes one of the world's wettest places, the slopes of Mount Waiʻaleʻale, which average 373 in (9,500 mm) of rainfall per year.
Argyroxiphium sandwicense subsp. macrocephalum, the east Maui silversword or Haleakala silversword, is a rare plant, part of the family Asteraceae. The silversword in general is referred to as ʻāhinahina in Hawaiian.
The silversword alliance, also known as the tarweeds, refers to an adaptive radiation of around 30 species in the composite or sunflower family, Asteraceae. The group is endemic to Hawaii, 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.
Wilkesia gymnoxiphium, is a species of flowering plant in the family Asteraceae that is endemic to the island of Kauaʻi in Hawaiʻi. It is classified as endangered on the IUCN Red List. Wilkesia is one of three genera, with Argyroxiphium and Dubautia that are believed to be descendant from a single species related to the North American tarweed. The members of these three genera constitute what is called the silversword alliance, a group whose exceedingly close genetic heritage is not reflected in their exceptionally diverse morphologies.
Cinnamomum burmanni, also known as Indonesian cinnamon, Padang cassia, Batavia cassia, or korintje, is one of several plants in the genus Cinnamomum whose bark is sold as the spice cinnamon. It is an evergreen tree native to southeast Asia.
Argyroxiphium sandwicense, the Hawaiʻi silversword, or hinahina is a species of silversword. It is endemic to Hawaii. The two subspecies are separated by geography. Both subspecies are rare, threatened and federally protected.
Psilotum nudum, the whisk fern, is a fernlike plant. Like the other species in the order Psilotales, it lacks roots.
Argyroxiphium caliginis, the ʻEke silversword, is a species of flowering plant in the family Asteraceae.
The Mauna Loa silversword, Argyroxiphium kauense, or Kaʻū silversword, is a rare species of flowering plant in the aster family. It is endemic to the eastern and southern slopes of Mauna Loa on the island of Hawaiʻi. A. kauense occurs in mountainous shrublands, bogs, and open mesic forest. The species is managed by the National Park Service and Hawaiʻi State Department of Forestry and Wildlife. It is a federally listed endangered species of the United States. There are three known populations remaining, for a total of fewer than 1000 individuals.
Dubautia arborea, the tree dubautia or Mauna Kea dubautia, is a species of flowering plant in the family Asteraceae. A member of the silversword alliance, it is endemic to the island of Hawaiʻi. It is a shrub or small tree. It is an endangered species that is threatened by feral grazing animals.
Cyperus laevigatus is a species of sedge known by the common name smooth flatsedge.
Wilkesia is a genus of Hawaiian plants in the tribe Madieae within the family Asteraceae. It contains two perennials, both of which are endemic to the island of Kauaʻi in Hawaiʻi. Wilkesia is a component of the silversword alliance and is named after Captain Charles Wilkes.
Argyroxiphium grayanum, commonly known as the greensword, is a species of flowering plant in the family Asteraceae, and a member of the silversword alliance, a group of over 50 species which are diverse in morphology and habitat but are genetically closely related.
Argyroxiphium sandwicense subsp. sandwicense, the Mauna Kea silversword, is a highly endangered flowering plant endemic to the island of Hawaiʻi of Hawaii. It is the "crown jewel" of the volcanic mountain Mauna Kea, from which it derives its English name. The Hawaiian name is ʻahinahina; it applies to silverswords more broadly. The Mauna Kea silversword was once common on the volcano, and extraordinary conservation efforts are being made to preserve the species.
Argyroxiphium × kai, commonly known as the Kai silversword, is a hybrid species of silversword plant in the family Asteraceae, and is a part of the silversword alliance. The name derived from the Hawaiian word “kai”, which translates to “sea”. It was described by David D. Keck in 1936. Argyroxiphium × kai is a natural hybrid between Argyroxiphium caliginis and Argyroxiphium grayanum, so the name Argyroxiphium calignis × grayanum can also apply, but is generally less common. It is endemic to Maui, Hawaii, where it grows between other Argyroxiphium species, primarily the two species that hybridized between each other. The population of the hybrid species is unknown, although it is likely that it may be endangered, or unstable due to invasive feral goats and pigs in its natural habitat. No conservation status has been assigned to Argyroxiphium × kai by the IUCN Red List, for it is a hybrid species, so a conservation status does not apply.
Argyroxiphium virescens × sandwicense subsp. macrocephalum, commonly known as the Pu'u 'Alaea greensword is a hybrid species of silversword plant in the family Asteraceae, and is a part of the silversword alliance. It is a hybrid between two taxons of silversword plant in the genus Argyroxiphium, being the presumably extinct Argyroxiphium virescens, and a subspecies, Argyroxiphium sandwicense subsp. macrocephalum. The hybrid species was discovered in 1989, when an individual flowered, which revealed hybridization features of two species of silversword. It is endemic to East Maui, primarily near the town of Pu’u Alaea, where it is seen growing beside other Argyroxiphium species. The population of the hybrid species is unknown, but is likely under threat of feral goats, and pigs that plague silversword plants.
Argyroxiphium sandwicense subsp. macrocephalum x Dubautia menziesii, commonly known as the Dubautia-silversword, is a hybrid species of silversword plant in the family Asteraceae, and is a part of the silversword alliance. The hybrid was formed between Argyroxiphium sandwicense subsp. macrocephalum and Dubautia menziesii, which are both species of plant native to the Haleakalā Shield Volcano, Maui, primarily in the Haleakalā Crater, that grow in alpine and subalpine zones. A specimen was recorded by Karl Magnacca in 2006, although there isn't clear evidence of whom first described the hybrid species.
