Sweden has as many as 90,000 lakes larger than one hectare. Most of these are either nutrient-poor with clear water and few plants (e.g. Lobelia dortmanna and Isoëtes spp.), like lake Vattern, or small ponds with brown water surrounded by floating mats of bog vegetation (e.g. sedges and Menyanthes trifoliata). Nutrient-rich lakes are found mostly in the south, and typically have dense reed stands, other emergent plants (e.g. Iris pseudacorus and Sparganium erectum), free-floating plants such as Hydrocharis morsus-ranae and Stratiotes aloides, and submerged vegetation with spp. of Potamogeton, Ranunculus, and others. The best known lakes in this category are undoubtedly Tåkern and Hornborgasjön.
