Case Study: Amur Cork Tree

Amur cork tree is currently the most reported taxon in the PGSIP database. A large deciduous tree with a broad, low-branched crown, Amur cork tree is stately in gardens & parks (see photo). However, public gardens contributing to PGSIP are seeing it escape from cultivation. After connecting and comparing notes related to their observations, the gardens participating in PGSIP found something curious: P. amurense is widely reported as dioecious in literature, meaning that male and female flowers occur on separate plants. However, observations at gardens indicate that its reproductive biology may be more complicated. "Male" trees that were fruitless for years, sometimes decades, have been observed producing fruit at some gardens, sometimes only on isolated branches. This indicates both that the reproductive biology of this taxon and its cultivated varieties deserve more study and that management strategies that call for planting only male cultivars may not fully address its spread from cultivation.

San Francisco