Hawai'i red cranesbill
Geranium arboreum A.Gray
Hawai‘i red cranesbill is a woody geranium with a strikingly uneven flower. Three upper petals stand upright, while the lower pair bend sharply backward. This bilateral arrangement gives the magenta blossom a very different outline from the radially arranged flowers familiar in many other true geraniums. US Fish and Wildlife Service: Hawaiian Red-flowered Geranium
Botanical name
Kew accepts Geranium arboreum in Geraniaceae, native only to Maui. Plants of the World Online: Geranium arboreum
Recognizing the plant
The plant forms a spreading, branched shrub that can reach two to four metres. Closely spaced alternate leaves are oval to heart-shaped and somewhat hairy, with conspicuous veins and small teeth along their margins. Hairy stipules below the leaf stalks remain after the leaves fall. Groups of one to four flowers arise near the leaf axils. The elongated fruit has five compartments, each containing a small, dark purple seed with a net-patterned surface. US Fish and Wildlife Service: Hawaiian Red-flowered Geranium
Native range
This species is endemic to Maui, with its habitat on the slopes of Haleakalā. Government accounts describe steep, damp, shaded gulches and stream banks within montane forest and subalpine shrubland. Plants of the World Online: Geranium arboreumUS Fish and Wildlife Service: Maui plant habitats
Ecological relationships
The recovery plan identifies native honeycreepers as probable important pollinators of these unusually shaped flowers. US Fish and Wildlife Service: Maui Plant Cluster Recovery Plan
Botanical sources
- Plants of the World Online: Geranium arboreum
- US Fish and Wildlife Service: Hawaiian Red-flowered Geranium
- US Fish and Wildlife Service: Maui plant habitats
- US Fish and Wildlife Service: Maui Plant Cluster Recovery Plan
Reviewed 2026-10-11. Seasonal development varies with location and growing conditions.