Samolus valerandi
Leaves very thin, basal leaves obovate, 3–4 cm long; cauline leaves narrower and smaller. Flowers on filiform pedicels in loose racemes. Corolla 8–10 mm diam., white. Glabrous, erect herb with flowering stems up to 30 cm high. Widespread. Margins of swamps and rivers. Fl. spring-summer. Common Brookweed or Water Pimpernel