Ginkgo

In the vicinity of the public toilet, two ginkgo trees frame the main avenue. Ginkgos are living fossils – they already existed at the time of the dinosaurs. Many species of ginkgo have become extinct in the course of the Earth's history, with Ginkgo biloba the only species that still exists today. However, it is at risk of extinction in the wild. There are only a few ginkgo forests left in its native country of China. In Asia, however, ginkgos have been cultivated in Buddhist temples for thousands of years. They have also been popular street trees in cities around the world for some time.

Ginkgo trees are either male or female. The two trees on the main avenue are both male. The tree by the wall, however, has a female branch at a height of about two metres, which produces fleshy seeds in autumn. This branch goes back to an experiment by garden director Joseph Franz von Jacquin (1766-1839), who wanted to find out whether the female branch would change its sex if he grafted it onto a male tree. The branch remained female and Jacquin thus proved that the sex of plants lies in the wood and is not determined by the sap of the male tree.

The tree is therefore a witness to the history of science. While Jacquin's father and his contemporaries ’only’ described God-given nature, Joseph Jacquin and others intervened in nature and manipulated it to gain new insights.