The eleventh tree on the tour stands in the grove of trees between the library and Mensa. It is a Bee-bee tree, also known as the Korean evodia, botanical name Tetradium daniellii (synonymously called Euodia hupehensis) of the rue family or Rutaceae.
It is a deciduous shrub or small tree whose height rarely exceeds 20 meters. Its bark is smooth and gray, similar to the copper beech. Its opposing leaves are between 15 and 40 centimeters long. The leaflets are pointed, five to fifteen centimeters long, half as wide, shiny dark green on top, dull on the underside. In autumn the foliage changes color only slightly.
The original areas of its distribution were China and Korea. It is found at altitudes from sea level to 3200 meters, mainly in forests or on their borders. The bee-bee tree prefers fresh to moist soils, rich in nutrients, and both sunny and shady locations. Its vigorous sinker root system requires a relatively large amount of space in width. The roots also reach deep soil layers, which is why the bee-bee tree can cope with periods of low rainfall. Bee-bee trees are short-lived, surviving only to around 50 years of age. In Central Europe, they are hardy and are planted mainly as a bee pasture.
Bee-bee trees carry numerous other names, owing to its flowers. The old name Euodia means good fragrance; hupehensis refers to the tree's home in the Chinese province of Hupeh. At flowering time between June and August, inflorescences of about five to fifteen centimeters in size form. The bee-bee tree is dioecious, i.e. female and male flowers are on separate individuals. It bears radially symmetrical flowers with whitish-green to brownish petals in large umbels up to 15 centimeters in diameter. The German names "Duftesche" and "Stinkesche" (scented or stinky ash) refer to the smell of the flowers. If the flower umbels are still pleasantly fragrant, the leaves exude an unusually intense odor when crushed. Because the flowers are so abundant and numerous and offer a lot of nectar, the plant is also called bee tree and honey ash, so it is planted mainly as a bee pasture.
The new name Tetradium daniellii refers to the fruits that grow in packs of four (tetrads). The epithet commemorates the British military surgeon Daniell, who brought them to Europe. The red bellow fruits ripen between August and November, bearing pinhead-sized, roundish, black seeds.
An edible oil is said to be extracted from the fruit. There are no consistent reports of medicinal uses.