Cibotium glaucum aka Hapu'u

Cibotium glaucum is an evergreen tree fern from the Hawaiian Islands. Its common names include Hawaiian tree fern and hapu’u pulu. It grows beneath the canopy in moist and wet forests. On Hawaii Island, it grows on damp volcanic slopes. Some plants grow close to sea level. Others live in cool, humid forests high on the slopes.

This slow-growing fern forms a trunk topped with arching fronds. Garden plants reach about 6–10 feet [1.8–3 metres] tall. Their spread can reach 10 feet [3.05 metres]. Rare plants reach about 25–26 feet [7.6–8 metres] tall. The thick trunk measures roughly 0.7–2 feet [0.2–0.6 metres] across. Fronds often measure 3–9 feet [0.9–2.7 metres] long. Useful Tropical Plants reports extremes near 20 feet [6 metres]. The blades divide two or three times into smaller leaflets. Their upper sides are medium green, with blue-green undersides. Yellow-brown hairs cover the frond bases and growing tips. These soft hairs are known as pulu. This fern does not flower. Spore cases grow on the undersides of its fronds.

Choose a sheltered site with partial or dappled shade. The plant also tolerates deep shade and some full sun. Hot, dry sites call for shade during midday heat. It prefers cool, moist air and protection from strong winds. Give it slightly acid soil that drains well but stays moist. Missouri Botanical Garden lists its water needs as moderate. It grows best in tropical and subtropical climates. Its listed hardiness range covers USDA zones 10–12. Frost harms it, and garden sites should stay above 40°F. In colder regions, a greenhouse offers a suitable growing space. Growers can raise new plants from spores or cuttings.

In frost-free gardens, it serves as a specimen or accent plant. Its evergreen crown provides interest through winter. Missouri Botanical Garden reports no major insect or disease problems. People once used pulu to fill pillows and mattresses. They also used it for wound dressings and embalming. Trunk fibres served as plant-basket liners and growing media. Heavy past harvesting for pulu damaged Hawaiian forests.

Useful Tropical Plants records cooked young fronds as food. People also ate the starchy trunk core during food shortages. It records traditional medicinal uses, including wound care. These records do not establish medical benefit. The source reports no known cases of toxicity for this species. That does not establish that all parts are safe to eat.