Unlike the Forest Botanical Garden which presents woody plants arranged in systematic groups, tree and shrub species within the Arboretum are arranged according to geographic regions of collection (China, Japan, Caucasus/ Asia Minor, Korea, and North America).
Special features of the Japan section
Declared a 'National Conservation Collection' (Nationale Schutzsammlung) the Japan section contains more than 200 woody plant species in 2011. It is situated around the Microbiology and Plant Pathology buildings, guest house, ENI (Europäisches Neurowissenschaftliches Institut), and Biozentrum (see map). The Japan section has been severely affected by development activities around the ENI and Biozentrum, resulting in a massive decline of its inventory. However, after completion of the buildings the new outdoor facilities will be incorporated into the Arboretum and the collection within the Japan section will continue to grow.
Japanese Wisteria in flower (Wisteria floribunda)
Characterized by a huge amount of decorative, woody plants worthy of being planted in a garden, the Japan section will delight plant lovers and garden owners alike. Floristic highlights include the cherry blossom in April and the display of colourful fruits and foliage by many of the section’s woody plants in fall.
The vegetation of Japan covers a wide geographical area extending from the subtropical Ryukyu Islands to the Kuril Islands, the latter being affected by subarctic conditions. Mountain forests experience high levels of precipitation and humidity. As a consequence of the enormous climatic gradient between northern and southern islands and a great degree of geographic isolation, the Japanese flora is extraordinarily rich in species.
'National Conservation Collection'
Declared a “National Conservation Collection” (Nationale Schutzsammlung) by the 'Botanical Gardens Association' (Verband Botanischer Gärten, VBG), the Japan section as a living reference collection plays a pivotal role in the conservation of gene resources of Japanese trees and shrubs. Since 1999, on behalf of the Federal Agency for Nature Conservation (Bundesamt für Naturschutz) the VBG, which represents Botanical Gardens of the German-speaking countries, has developed a concept to identify important collections, worthy of particular attention. This concept aims at the conservation of cultural heritage and plant biodiversity, as well as protection and continuity of botanical collections. Other 'National Conservation Collections' include the Korea and Caucasus/ Asia Minor sections of the Plant Geographic Arboretum.
Notable trees within the Japan section
The southernmost representatives of the Japanese flora to be seen in the section, namely Hinoki or Japanese Cypress (Chamaecyparis obtusa) and Japanese White Pine (Pinus parviflora), naturally occur in cool-temperate to alpine mountain ranges on Kyushu and Shikoku Islands, both of which are in the subtropics.
Most of the Japanese woody plants that are capable of withstanding the German winter originate from the temperate to alpine regions on the main island Honshu, e.g. Japanese Maple (Acer palmatum), Cornus controversa, Kobushi Magnolia (Magnolia kobus), and Sargent’s Cherry (Prunus sargentii).
Northern Japanese plants include Sakhalin Fir (Abies sachalinensis), Betula maximowicziana, Japanese Yew (Taxus cuspidata), and Laurel-leaf Poplar (Populus laurifolia).
In the wild Sargent’s Cherry (Prunus sargentii) grows in Japan and on Sakhalin, the latter being situated in eastern Russia, only a few miles north of Japan. In Europe this flowering cherry is quite frequent in parks and botanical gardens. In April Prunus sargentii is completely covered in simple, pink flowers up to 4cm (app. 1.6in) in size that form umbels comprising two to four flowers.
Book author Hans-Dieter Warda cuts it right to the chase:
“Plant specialists and plant lovers often avoid clear statements when it comes to evaluating a plant species. Rather they might say things like ‘…belongs to the most precious within this group.’
“About Prunus sargentii you can say by all means: because of its picturesque growth, early and overwhelming abundance of flowers, luminous, orange-red foliage in fall, and not least because of its decorative bark in winter, it is the most beautiful flowering Cherry in our gardens.” (1)
(1) Warda, Hans-Dieter, 1998. Das große Buch der Garten- und Landschaftsgehölze. Bruns Pflanzen Export GmbH, Bad Zwischenahn.
Sargent’s Cherry blossom in front of the Institute of Microbiology