Argyroxiphium sandwicense ssp. macrocephalum (Haleakalā silversword)

Argyroxiphium sandwicense DC. ssp. macrocephalum (A. Gray) Mérat

Haleakalā silversword

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Asteridae	A large class that encompasses asters
Order	Asterales	Flowering plants with a central disk flower and surrounding petals, like daisies
Family	Asteraceae	The aster family, which also includes daisies and sunflowers; from the Greek ἀστήρ, “star,” for the star-shaped flowers
Genus	Argyroxiphium	A small genus with common names of “silversword” or “greensword”
Species	sandwicense	From the “Sandwich Islands,” the name given the Hawaiian islands by James Cook during the 1770s
ssp.	macrocephalum	With a large head

About plant names...

Haleakalā is a huge shield volcano that makes up most of the island of Maui in Hawaii. It tops out at just over 10,000 feet and is the only place in the world where you can find the rare and threatened silversword. Or more precisely, the only place you can find Haleakalān silversword—a close relative can be found on Mauna Kea on the big island of Hawaii. The photos by Erin Senoz are reproduced here from EPOD, a service of NASA’s Earth Science Division.

Identification: Silversword is unmistakable in appearance, and in the unforgiving volcanic detritus of a young cinder cone there are few nearby plants with which it could be confused. It forms a dense pin cushion of silver-gray, sharp-tipped narrow leaves, often with a hula skirt of older, dried leaves below the living ones. (The Hawaiian name, ʻāhinahina, means “very gray.”) The Haleakalā variety of silversword is found only at elevations between 1.3 mi (2.1 km) and the summit, at 1.9 mi (3 km). When the plant reaches a diameter of about 20" (50 cm), it produces a single, spectacular spike of maroon-colored flowers up to 6½' (2 m) high. The flowers produce seed and the plant dies.

Silversword’s rather extreme approach to reproduction—growing for 50 years or so, then flowering and dying—is by no means unique. Plants with this curious trait are called monocarpic, and agaves and some yuccas are among them.

Online References:

Argyroxiphium sandwicense ssp. macrocephalum on epod.usra.edu from the Earth Science Picture of the Day

Argyroxiphium sandwicense ssp. macrocephalum on Wikipedia

Argyroxiphium sandwicense ssp. macrocephalum at the United States National Parks Service

Argyroxiphium sandwicense ssp. macrocephalum on ARKive: Images of Life on Earth

Argyroxiphium sandwicense ssp. macrocephalum on www.botany.hawaii.edu

Argyroxiphium sandwicense ssp. macrocephalum on the International Union for Conservation of Nature and Natural Resources Red List of Threatened Species

Argyroxiphium sandwicense subsp. macrocephalum

Argyroxiphium macrocephalum A. Gray

Argyroxiphium sandwicense ssp. macrocephalum description by Thomas H. Kent, last updated 25 May 2020.

12/12/2020 · Haleakalā Volcano, Maui, Hawaii · By Erin Senoz

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