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 plant is wet meadows, banks of streams, river-sides, damp woods. The habit is erect. The plant resembles V. officinalis (V. mikanii), of which it has been considered a variety, but here there are 4-6 pairs of lance-shaped leaflets, which are toothed all round. The leaves are pinnate, alternate. The leaflets in the radical leaves are ovate to acute, those of the stem-leaves oblong to lance-shaped, toothed on both edges. The terminal leaflets of the radical leaves are sometimes the largest. The plant produces large stolons. The plant is 2-4 ft. in height. The flowers bloom from June to August, and the plant is a herbaceous perennial.