A member of the eucalyptus family, Myrtaceae, mangkono (Xanthostemon verdugonianus) bears attractive blossoms that later yield half-moon-shaped, red seeds. This tropical evergreen tree is also commonly called the Philippine ironwood and dubbed the "hardest tree in the Philippines." Grow it in U.S. Department of Agriculture winter hardiness zone 11 and warmer.
Mangokono grows naturally only in the central Philippines on Surigao's Dinagat Island, Homonhon Island in Samar, Babatngon, Leyte, and in Palawan. Nationwide it now is considered rare and endangered according to the ASEAN Regional Centre for Biodiversity Conservation.
An evergreen tree with an upright, oval habit, mangkono's trunk can reach a diameter of 20 to 36 inches and overall height of 30 to 40 feet. The trunk is fluted and carries small twigs as well as architecturally irregular but picturesque branches. Leaves are tongue to rounded oval in shape and green with a leathery texture. The ornate, rounded clusters of bright, blood-red flowers occur on branch tips and have five small petals but many erect whiskerlike stamens. The dry fruits split open into three sections to release tiny half-moon seeds.
Mangkono trees tolerate low-fertility soils but grow much more lushly in more sandy loam gardenlike soils that are rich in organic matter. In the heat of the long growing season, provide lots of water but reduce watering during the winter dry season associated with the tropics. According to the Haribon Foundation, Filipinos who live on the islands where this tree naturally grows believe the tree's wood becomes tougher when it is well-watered. Provide full to partial sunlight exposures for more abundant flowering displays, but no fewer than five hours of direct sunlight daily. It grows nicely in an open grove with other tropical trees and palms.
Mangkono wood is among the hardest and densest in the world, often used as a substitute for the dense hard wood of the lignum-vitae (Guaicum spp.) trees of the Caribbean. Often, trees are allowed to grow to a diameter of a few inches before being cut. Gas-powered diamond blades cooled by water more readily cut the wood as compared to axes, which take considerably more time and energy.
Mangkono makes a superb material for the bearing or stern bushing of steamship propeller shafts. It is also used as rollers, shears, saw guide blocks, tool handles, novelties, poles and piles for wharfs and bridges. Smaller-diameter trunks or branches are heavily used as house posts, according to the Haribon Foundation. The gnarled trunks and branches and vividly colored flowers also make mangkono a magnificent ornamental tree, albeit rare, for tropical gardens.