Ulmus minor Mill., the field elm, is by far the most polymorphic of the European species, although its taxonomy remains a matter of contention. Its natural range is predominantly south European, extending to Asia Minor and Iran; its northern outposts are the Baltic islands of Öland and Gotland, although it may have been introduced by humans. The tree's typical habitat is low-lying forest along the main rivers, growing in association with oak and ash, where it tolerates summer floods as well as droughts.

Sliven is the eighth-largest city in Bulgaria and the administrative and industrial centre of Sliven Province and municipality in Northern Thrace. It is situated in the Sliven Valley at the foothills of the Balkan Mountains.