Santalum paniculatum aka Mountain Sandalwood

Santalum paniculatum is an evergreen tree native to Hawaii. Common names include mountain sandalwood, Hawaiian sandalwood, and ‘iliahi. It belongs to the Santalaceae family. It grows in dry forests on lava and cinder cones. It also occurs in wetter forests at higher sites. Its wild range spans elevations of 1,480–8,370 feet [450–2,550 metres].

This slow-growing plant forms a shrub or a bushy tree. Several main stems often support a broad crown. Garden references give a height and spread of 25 feet [7.5 metres]. Broader accounts report heights of 10–33 feet [3–10 metres]. Exceptional trees reach 66 feet [20 metres]. The crown may spread as wide as the tree stands tall. Its narrow, oval leaves have a blue-green hue. Small flowers grow at the tips of branches. Bees and other insects pollinate them. The fleshy fruit turns purple or black when ripe. Each fruit holds one seed.

This tree is a root hemi-parasite. Its roots draw water and nutrients from nearby host plants. Without a host, it grows poorly. It prefers shade from the sides, with little shade above. Deep shade limits growth. Full sun can suit plants linked to a suitable host. Light to medium soil with good drainage gives the best growth. It also tolerates shallow soils and low soil fertility. It prefers near-neutral to slightly alkaline soil but tolerates more acid ground. Dry soil suits it, and it can withstand drought and sea exposure. Sources place it in USDA zones 10–11, in frost-free conditions.

Hawaiian gardeners grow it as an ornamental tree. Its scented heartwood yields oil for perfume, cosmetics, and incense. People have also used the oil to scent hair and skin preparations. Wood scraps and powder can serve as incense material. These uses give both the wood and oil trade value. Traditional remedies used powdered heartwood with other plants for sores and venereal disease. People also used leaf washes for dandruff and head lice. These records describe past uses, not proof of safe treatment.

The seeds are edible, though scarce seed is better kept for propagation. Fresh seed loses viability soon, so prompt sowing helps. A small nick in the seed coat can aid germination. Seedlings need a suitable host as they grow. The sources report no known hazards, but do not establish comprehensive safety. They flag weed potential without describing its scale. They give no specific account of pests or diseases.