Potamogeton berchtoldii, common name small pondweed is an aquatic plant. Potamogeton berchtoldii is native to Europe (including Britain, Ireland, continental Europe, Scandinavia), the Middle East, North America (Canada, USA), Asia (Bhutan, China, Japan, Kazakhstan, Korea, Tajikistan, Turkmenistan, Russia, Uzbekistan), Asia Minor and the Middle East (Iraq, Iran, Turkey). Ecology and Potamogeton berchtoldii has a wide ecological tolerance, growing in lakes, ponds, ditches, slow-flowing streams and rivers, temporary pools and sometimes appearing in artificial habitats such as cattle troughs. It is a good colonist and may quickly exploit new habitat. The production of large numbers of both turions and seed likely allows it to quickly exploit new or disturbed habitat, but in stable environments it is likely to be outcompeted by more robust plants. In Britain, small pondweed is common and widespread. It is probably under-recorded due to its relatively small size and confusion with P. pusillus. Although it does not occur in very acid environments, small pondweed is otherwise tolerant of a wide range of water chemistry and seems able to survive in eutrophic conditions. However, it is less tolerant of high nutrient levels than the related and very similar P. pusillus. It is the only British fine-leaved pondweed likely to be encountered in oligotrophic lakes, where it generally grows in deeper water with Isoetes and Nitella spp. Small pondweed is not in cultivation, though it is likely to spontaneously colonise new ponds, probably via waterfowl. It is unlikely to persist for long in this environment, however, unless competing plants are regularly cleared. Its small stature and noninvasive habit make it suitable for growing in a pond or aquarium.