The Ruizia mauritiana is a large green shrub with cascading leaves shaped like lovehearts. There’s one just off the main walkway through the magnificent Temperate House in London’s Kew Gardens, a Victorian marvel nearly 200 metres long. Among all the surrounding greenery, the plant looks unassuming – but examples of this specimen are extremely rare. In fact, by the mid-1990s, it was thought to be extinct in the wild. But then came some thrilling news: a 10-metre tall example had been spotted in the Mauritian highlands. And soon Kew’s scientists were wading through a guava thicket in the east African island nation to take some cuttings.
Those scientists would go on to make a remarkable discovery. Previously, the Ruizia mauritiana was thought only to grow male flowers (whose stamen produce pollen). But, during its cultivation, researchers realised that this wasn’t the case: the sex of this plant’s flowers depends on the temperature. In hot conditions, it grows male flowers. But in cooler climates, it produces female ones (whose stigmata receive pollen).
