[ggm]

We probably disagree what ultra rare means. They're significantly less common than rhododendrons. They're more common than Wollemi pines.

It's headline hyperbole. They aren't common, any more than hothouse structures capable of growing them are. Same with giant lilypads (for instance).

Fruit bearing Banana plants and Cocoa pods are rare enough in Britain that Kew and Edinburgh Botanical gardens used to have little movable arrows on sticks to show you the fruit if you walked around the hothouse. Same with giant bamboo to show you how fast it grew in a day: if you came morning and afternoon same day you could see the growth.