Zannichellia (common name horned pondweed) is a genus of submerged aquatic flowering plant. The genus is fully adapted to an aquatic life cycle including underwater pollination. Zannichellia has threadlike leaves and tiny flowers. There are perhaps five species, including Zannichellia palustris.Zannichellia, after G.G. Zannichelli, 1662-1729, Italian botanist.