Scientific Name
Argyroxiphium sandwicense DC.
Synonym(s)
Argyrophyton douglasii, Dubautia sandwicensis
Common Name(s)
Hawai'i Silversword, Hawaiian Silversword, Mauna Kea Silversword
Scientific Classification
Family: Asteraceae
Subfamily: Asteroideae
Tribe: Madieae
Genus: Argyroxiphium
Etymology
The specific epithet "sandwicense" (pronounced "sand-wich-EN-see") means "of or from the Sandwich Islands (Hawaii)" and refers to the origin of this species. The name "Sandwich Islands" was originally given by Captain Cook to the Hawaiian Islands in honor of the Earl of Sandwich.
Origin
Argyroxiphium sandwicense is endemic to Hawaii. It grows only on the upper slopes of Mauna Kea at elevations between 8,530 and 12,470 feet (2,600 to 3,800 m).
Description
Argyroxiphium sandwicense is a rare plant that forms a large, ball-shaped rosette of numerous narrow, lance-shaped leaves coated with silvery hairs. The rosette can grow up to 2.5 feet (75 cm) in diameter, usually solitary, but some specimens produce offsets and form a tight cluster of rosettes of various sizes. The leaves can measure up to 16 inches (40 cm) long and 0.6 inches (1.5 cm) wide.
The rosette may live from 3 to more than 50 years before flowering, flowers only once, and then dies. Mature rosettes send up a spectacular stalk with numerous short branches, each terminating in a single head of flowers in summer. The flower stalk can grow up to 10 feet (3) tall, while the flower heads can reach a diameter of 0.8 inches (2 cm) and have white to pink ray florets and pink to maroon disk florets. A rosette that flowers in the absence of other flowering rosettes can produce a few black achenes that contain a single seed.
Subspecies of Argyroxiphium sandwicense
- Argyroxiphium sandwicense subsp. macrocephalum
- Argyroxiphium sandwicense subsp. sandwicense
How to Grow and Care for Argyroxiphium sandwicense
Hardiness: USDA hardiness zone 10a to 10b: from 30°F (-1.1°C) to 40°F (4.4°C).
The silversword alliance comprises approximately 50 plant species in three genera, all endemic to the Hawaiian Islands. They get their common name from the visually impressive silversword.
These plants only flower once in their lifetime. The silver rosettes grow for several years before the inflorescence ascends skywards. Flowers appear from mid-June to November, and the whole plant dies after the seeds have been shed. These exotic-looking plants are ideally suited to their harsh environment. The silver leaves reflect sunlight, while their shape prevents moisture loss and protects the plant's more delicate center from predation.
These attractive plants were previously collected as curiosities. Climbers on the mountains would dig them up as proof that they had reached the summit. Populations were further depleted by browsing and trampling by goats and cattle in the area. Today, Argyroxiphium sandwicense is restricted to a single population of as few as 30 plants in the Wailuku River basin on Mauna Kea in Hawaii. These plants are at risk due to the small size and restricted range of their populations, which are vulnerable to chance events.
The Hawai'i Silversword is protected in Hawaii.
Links
- Back to genus Argyroxiphium
- Succupedia: Browse succulents by Scientific Name, Common Name, Genus, Family, USDA Hardiness Zone, Origin, or cacti by Genus
Photo Gallery
Click on a photo to see a larger version.
