Flower:

Solitary flowers at the end of branching stems in the upper part of the plant. Flowers are flattened, about 1/8-inch across, with 4 petal-like sepals that are broadly triangular to egg-shaped to semi-circular, 1 opposite pair often slightly larger than the other. Sepals are green, yellowish green or reddish green, sometimes purple marked. In the center is a transluscent disk, green to brown to reddish, surrounded by 4 to 8 (usually 8) short stamens, typically purple, red or orange tipped, though our specimen has yellow stamens. A pair of leaf-like bracts about as large as the flower sit at the base of the flower, usually just above a leaf that looks like a larger bract.

Leaves and stems:

Leaves are round to egg-shaped to fan-shaped, 3/8 to 5/8 inch long and up to ¾ inch wide, hairless, scalloped or shallowly notched or lobed around the edges, with little or no leaf stalk. Leaves are mostly opposite but may be alternate in the upper branches. Stems trail along the ground, rooting at the nodes. Upper branches are prostrate to ascending.

Notes:

At first glance of the marshy bend in the brook this species appeared to be emerging watercress (Nasturtium officinale) or perhaps giant chickweed (Myosoton aquaticum) but turned out to be a new find for us. We didn't think of tasting it—may try next time.