From a botanical viewpoint lake Husby Sø has one of the richest floras in the country. In 2005 a total of 54 plant species were recorded, of which 41 were underwater plants, 6 were varieties of stoneworts, one was a type of moss and there were also 7 species of floating aquatic vegetation. A total of 14 of the 19 varieties of pondweed in Denmark have also been recoded here, together with three pondweed crossbreeds. A total of 10 flowering plants are on the Danish yellow list, i.e. species that are in decline on a national scale in recent years. The species floating water-plantain that occurs here is on the Danish red list (vulnerable) and is one of the species of special concern in the EU. Water-plantain appears to be strongly threatened by overgrowth by, for example, reeds and lakeshore bulrushes. Another factor is the reduced dynamism in the lake because of the dams along the shore. The area is maintained in cooperation with local landowners by cutting vegetation along the shore and grazing.