The role of botanical gardens in plant conservation©
Botanical gardens are much about colourful display and arboreal grandeur. Until relatively recently, though, most botanical gardens were largely collections of exotic plants arranged for the pleasure of the public - not unlike the zoos of the past. In other words, exotic eye candy to entertain the customer and not so much about conservation. University-based botanical gardens have always provided special gardens and research collections for the education of experts, but these were mostly inaccessible. Essentially, the typical garden visitor would have no clue as to the value of the plants beyond any intrinsic beauty or other esthetic appeal they might have. It's worth noting that the earliest European botanical gardens were cloistered herb gardens administered by Latin-speaking monks. The walls and yew hedges surrounding them were meant to keep the knowledge in and the riff-raff out. Such academic traditions have been broken - although not always completely - the various kinds of interpretive signage common in modern botanical gardens being an indicator of the newfound willingness to communicate with the public.
Justice, D. 2016. The role of botanical gardens in plant conservation©. Acta Hort. (ISHS) 1140:127-130