Q: The attached photos are of a beautiful flowering plant that grows on the edge of the dam at the lake where I live. Do you know what it is?
A: It looks like turtlehead, Chelone lyonii.
This interesting native perennial loves damp spots and will spread to make nice patches along streams or ponds. The blooms usually occur July – September. It dies back to the ground in winter but sprouts vigorously in April.
Since it can be floppy if allowed to grow too tall, shear it to 8″ when the clump exceeds 12″ tall. This will produce subsequent shorter sprouts and more flowers.