Iris pseudacorus, yellow iris is a very water-loving plant, often growing directly from it! You'd see it around rivers, ponds, both wild and within villages.
Three different variants (for diversity) in four different season cycles are done.
A biome needs 32 sprites. These only account for 3 of those texture slots.
You've already seen the willow sprite. There will need to be reeds, nettles, more willows, poplars, alders to compliment the set...perhaps also some natural features like very mossy rocks and stumps!