It is the world's only one-needled pine tree and can live for 1,000 years.
The US native is rare because it is difficult to germinate and is rarely seen for sale. But one newly-propagated specimen was recently spotted at Ashwood Nurseries in Stowbridge, Staffordshire, by Aberglasney operations director Graham Rankin.
Two mature specimens exist in the UK - one at the Cambridge Botanic Garden and the other in Derbyshire.
"The Pinus monophylla is native to the USA (Idaho, Utah, Nevada, Arizona and California) and Mexico, where in the arid conditions it can thrive for up to a millennium," said Rankin. "How it will prosper here, we shall have to wait and see. It might not approve of the slightly cooler weather in west Wales."