Silene hawaiiensis is a critically endangered species of flowering plant in the family Caryophyllaceae, commonly known as the pinks or carnation family. It is a subshrub endemic to the Hawaiian Islands, specifically found on the islands of Maui and Hawaiʻi (the Big Island).
Taxonomy and Etymology
- Kingdom: Plantae
- Clade: Tracheophytes
- Clade: Angiosperms
- Clade: Eudicots
- Order: Caryophyllales
- Family: Caryophyllaceae
- Genus: Silene
- Species: S. hawaiiensis
The genus name Silene is thought to be derived from Silenus, the mythological foster father of Bacchus, who was often depicted as covered in sticky, foamy substances, similar to the glandular hairs found on some Silene species. The specific epithet hawaiiensis refers to its native range in the Hawaiian Islands.
Description Silene hawaiiensis is a perennial subshrub typically growing to about 0.3 to 1 meter (1 to 3 feet) tall. It features slender, branching stems and narrow, linear to lanceolate leaves that are typically 2.5 to 7 cm (1 to 2.8 inches) long. The leaves are opposite and can be covered with fine hairs. The flowers are relatively small, often white or greenish-white, and are arranged in loose clusters at the ends of the stems or in the leaf axils. Each flower has five petals, which are usually notched or bilobed at the tip, and a prominent calyx. The fruit is a capsule containing numerous small seeds.
Habitat and Distribution This species is narrowly endemic to the Hawaiian Islands, primarily found on dry, rocky slopes, cliffs, and in open shrublands at elevations ranging from approximately 300 to 2,000 meters (1,000 to 6,500 feet). It prefers well-drained, often volcanic soils and is adapted to arid or semi-arid conditions. Its populations are highly fragmented and restricted to specific microhabitats on Maui and Hawaiʻi.
Conservation Status Silene hawaiiensis is listed as Critically Endangered by the International Union for Conservation of Nature (IUCN) and is also recognized as an endangered species under the U.S. Endangered Species Act. The primary threats to its survival include:
- Habitat degradation and loss: Due to development, agriculture, and invasive plant species.
- Competition from invasive non-native plants: Introduced species outcompete Silene hawaiiensis for resources and alter its habitat.
- Browsing by feral ungulates: Goats, pigs, and other introduced animals graze on the plants, preventing regeneration.
- Fire: Increased frequency and intensity of wildfires pose a significant threat.
- Stochastic events: Small population sizes make the species highly vulnerable to random events and genetic drift.
Conservation efforts include fencing to exclude ungulates, control of invasive species, habitat restoration, and ex situ conservation through seed banking and propagation in botanical gardens.