Nuphar lutea

Vigorous water plant floating, leaves lying flat on the water; invading large areas with meter-long rhizomes as thick as your arm on the floor of the pond; very strong-growing.

Depends on water level; leafe stalkes up to 200 cm long.

Above water level, like buttercups, up to 4 cm large, golden yellow, June to August; slightly sweet fragrance.

Plate-size, perfectly round, pale fresh green, leathery; leaves raised off the water when water is not rough enough; in the first year after planting or at water depths above 250 cm, leaves only underwater; slender, very wavy, light green.

Sun to semi-shade, likes warmth, frost hardy.

Very nutritious, swamp, humic or loamy gravel, optimal water depth 75-200 cm, though sometimes 400-600 cm; stagnant or slowly flowing water; moderately tolerant of salt.

The rhizomes are filled with air and must be weighed down with a rock to keep them from floating during planting and establishment.