Endangered Euphorbias

Euphorbia Stygiana Conservation Programme


Euphorbia stygiana is a hardy shrub which exists in the wild only in the Azores. As an “oceanic island endemic” it is inherently vulnerable to loss and when numbers started to decline, Portuguese botanists working on a recovery programme realized that it was not regenerating in its natural habitat and was in danger of becoming extinct.

As a National Plant Collection holder of Euphorbias, the Oxford Botanic Garden, tasked a team to carry out on an ex situ conservation programme – that is conserving the endangered species “in captivity”, rather than in its native habitat.

Senior Horticulturalist Clare Kelly, worked out how to propagate by cuttings so that numbers could be increased and plants supplied to other Botanic Gardens.  Three biology undergraduates took on the Euphorbia as an academic project. Susan MacBurney drew up a propagation protocol that delivered an 85% success rate when growing plants from seed.  She also came up with a pest control regime.  Julia Jeans investigated the seed biology including dormancy and storage.  Finally Helen Humphries looked at why the Oxford Botanic Garden’s population of Euphorbia stygiana was not reproducing from the seed that fell in the soil below the parents.  She discovered that the Garden’s wrens were eating the seeds.

The work of these four women has allowed the Oxford Botanic Garden to establish a self-propagating population of Euphorbia stygiana and to pass this knowledge on to other botanists. It is also an encouraging demonstration that species loss can be tackled by small teams, one species at a time.