This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The habitat of this water-lily is small Scottish lakes. The plant has the water-lily habit, being aquatic, resembling the Yellow Water-lily, from which it differs in the smaller, more-rounded petals, and shorter anthers. The leaves are heart-shaped, oblong, 2-lobed below, the lobes distant, spreading at length. The submerged leaves are thin and transparent, wavy, kidney-shaped. The leaf-stalk is 2-edged. The flowers are small and yellow. There are 5 sepals. The stigma is rayed at the margin, with 8-10 rays, and these form acute teeth. The anthers are oblong, not twice as long as broad. The capsule is furrowed above. The plant is floating. The flowers are in bloom from June to August. The plant is a herbaceous perennial.