Text and pictures by N. Köster
Botanical gardens can help conserve threatened plant species from extinction, whether locally, regionally or globally, through ex situ collections. For this purpose, plants are used and propagated ex situ, i.e. in a scientific plant collection outside their natural habitat. Thus, the survival of endangered wild populations via horticulture can be ensured in the short to medium term. In the long run, however, this must be accompanied by adequate protection in situ, ie at the wildlife sites of the species. Once this has been ensured, ex situ collections of documented wild origins can make an effective contribution to supporting or eventually resettling the threatened wild populations at their original location.
The Botanical Garden Tübingen is dedicated to the conservation of endangered native wild plants. Regional focus is on the immediate surroundings of Tübingen and the Swabian Alb. In collaboration with local conservation groups, species are identified where the collection and reproduction in the Botanical Garden can in a meaningful way contribute to securing wild populations.
A success story of the past years represents the breeding of the 'Knockige Mastkraut' (Sagina nodosa), which was close to extinction in Baden-Würrttemberg. From the 1997 only 12 remaining plants in a fen near Ulm, seeds and Brutknöllchen were propagated in Tübingen, these new plants could be replanted in the wild already in the following year. On surfaces cleared from topsoil, a total of 240 plants were replanted, these multiplied considerably in the following years.
The extremely rare species in the immediate surroundings of Tübingen include the Hungarian Platterbse (Lathyrus pannonicus spp. Collinus) and the Zottige Fahnenwicke (Oxytropis pilosa), each of which occure in just two locations in Baden-Württemberg. Their populations grow in sunny spots near the edge of woods and in the dry and semi-arid grasslands of the southern slopes of the Tübinger Spitzberg form tiny outposts of the respective main habitats in the Pontic-Pannonian steppes of Eastern Europe.