“It can cause blurred vision, irregular heartbeat, low blood pressure and potential fatality…”

Across the island of Socotra, in the Indian Ocean, unique-looking trees dot the landscape.

One is the cloud-shaped Socotra dragon tree (or dragon blood tree), which is named after the dark red resin that spills from its bark if cut.

The other is the Socotra desert rose. While there are several subspecies of desert rose, the one found on Socotra is native to the isolated Yemeni island.

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It’s also known as the bottle tree – and it’s easy to see why. The bulbous, swollen-looking trunk can grow up to 2.4 metres (8 feet) in diameter at the base and stores plenty of water so it can survive the harsh desert landscape.

From early March until late April, it erupts with striking pink and white flowers. But these beautiful blooms hide a secret – the tree is poisonous.

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The sap contains cardiac glycosides, which are sometimes used in medicine to treat congestive heart failure or an irregular heartbeat. These work by increasing the force of the heart’s contractions while simultaneously slowing heart rate.   

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If a large, unregulated amount is taken, however, cardiac glycoside overdose can occur, with symptoms such as blurred vision, irregular heartbeat, low blood pressure and potential fatality.

Other subspecies of the desert rose are found across Southern Africa, Eastern Africa, Saudi Arabia and Yemen. Interestingly, caterpillars of the polka-dot wasp moth (native to the Caribbean) have been observed feeding on the desert rose.

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