Mauna Kea silversword
| Mauna Kea silversword Argyroxiphium sandwicense subsp. sandwicense |
|
|---|---|
 |
|
| Mauna Kea silversword on Mauna Kea (note protective fence) | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Tribe: | Madieae |
| Genus: | Argyroxiphium |
| Species: | A. sandwicense |
| Subspecies: | A. s. subsp. sandwicense |
| Trinomial name | |
|
Argyroxiphium sandwicense subsp. sandwicense |
|
Argyroxiphium sandwicense subsp. sandwicense, the Mauna Kea silversword, is a highly endangered flowering plant endemic to the island of Hawaiʻi (Big Island) 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.
Closely related to the Haleakala silversword (Argyroxiphium sandwicense subsp. macrocephalum) and in the family Asteraceae, the Mauna Kea silversword is a member of the silversword alliance, a group of approximately 50 species in three genera, all endemic to the Hawaiian islands. Their diverse morphologies belie extremely close genetic kinship and suggest extremely rapid evolution from a single precursor species. The silversword alliance is considered the most dramatic example of adaptive radiation among plants in Hawaii, illustrating the role of isolation and distinctive ecological conditions in promoting evolution.
The Mauna Kea silversword is an erect, single-stemmed and monocarpic or rarely branched and polycarpic basally woody herb, producing a globe-shaped cluster of thick, spirally arranged, sword-shaped silvery-green floccose-sericeous, linear-ligulate to linear-lanceolate leaves growing in a rosette. The epigeal or nearly epigeal rosette may become 0.6 m or more in diameter with individual leaves up to 0.3 m long and is usually less than 1.3 cm wide.
The leaves are completely covered with a dense layer of long silvery hairs. The leaves of all silverswords have an unusual and important ability to store water as a gel in intracellular spaces where other plant leaves contain air.
The flowering stalk, which appears in a few weeks before flowering, is narrow, but may reach nearly 3 m in height. It is composed of numerous, very sticky stalklets bearing up to 600 flowering heads about 2.5 cm in diameter, each containing 500 individual flowers. Each head has about a dozen pink to maroon petal-like ray flowers around its periphery.
...
Wikipedia