Rare orchid found growing on Oxford Brookes campus roof

The White Helleborine is listed as Vulnerable on the Great Britain Plant Red List.

But it was found growing on the green roofs of Oxford Brookes University’s John Henry Brookes Building during a plant survey led by Dr Andrew Lack, a Senior Lecturer in Environmental Biology.

Dr Lack said: “That was the find of the day, a totally unexpected orchid that I have not seen there before and is almost confined to the Chilterns within Oxfordshire.”

The green roofs, installed on buildings opened since 2012 including the Colonnade, Abercrombie extension and John Payne Building, were originally planted with drought-resistant stonecrop (Sedum) species.

Over time, they have evolved into semi-wild habitats supporting more than 100 plant species, including wild clary, salad burnet, ladies’ bedstraw, and at least six species of cranesbill.

Viper’s bugloss, a striking blue-flowered plant, is growing in some quantity across the roofs of the John Henry Brookes Building and is a hit with the bees.

The most unusual recent addition to the roofs is night-flowering catchfly, a nationally declining annual now known in Oxfordshire from only a handful of sites in the north-west of the county.

Dr Lack said: “We must treasure them, whole ecosystems largely invisible above our heads but adding considerably to the biodiversity of our campus.”

However, not all new arrivals are welcome.

Woody seedlings such as birch, willow, sycamore, buddleia and bramble have started to establish, posing a risk to the structural integrity of the roofs.

Dr Lack added: “Rogue tree and shrub seedlings could prove destructive for the roofs and will need to be removed.”