This is the only tree on Earth that grows intense blue-coloured fruit. It grows in...

Native to tropical Australia, Papua New Guinea, and parts of Indonesia, the blue quandong is a tall rainforest tree with spreading branches. (Image credit: Homegrownpalmwoods/Facebook)

For centuries, botanists believed nature had no truly blue fruits. Even those labeled “blue”—like blueberries or blue corn—are, on closer inspection, shades of purple or indigo. But deep in the rainforests of Australia and Southeast Asia grows a tree that defies this rule: Elaeocarpus angustifolius, better known as the blue quandong, blue fig, or blue marble tree.

The fruit of the blue quandong is so vividly cobalt that most assume it’s digitally enhanced. Yet under natural sunlight, it gleams like a metallic jewel. Measuring just 1–2 cm in diameter, these hard, spherical fruits are considered by researchers to have the most intense natural blue hue in the plant kingdom, Forbes reported.

Fruit doesn't contain any blue pigment

What makes this fruit extraordinary is that it contains no blue pigment at all. Unlike most blue plants, which rely on anthocyanins—pigments that shift color with pH—the blue quandong achieves its hue through structural coloration. Scientists discovered this when grinding the fruit to extract pigment: instead of blue, the material turned a dull grey, Forbes reported.

Structural coloration works like an optical illusion. Microscopic layers in the fruit’s skin scatter light in such a way that only blue wavelengths reflect back to the eye. It’s the same principle that gives peacock feathers and butterfly wings their iridescent shimmer—but in plants, this phenomenon is extremely rare.

Where it grows

Native to tropical Australia, Papua New Guinea, and parts of Indonesia, the blue quandong is a tall rainforest tree with spreading branches. Its jewel-like fruits stand out even in dim light, making them a visual marvel and a scientific curiosity.

Why it matters

The discovery of structural coloration in plants opens new doors for biomimicry and sustainable colour technologies. For now, the blue marble tree remains a reminder that nature still holds secrets—and sometimes, those secrets are dazzlingly blue.