Rorippa nasturtium-aquaticum (syn. Nasturtium officinale) is very common in Brisbane creeks. Found in disturbed wetlands, drains, seepages and creeks. Introduced from Europe, probably for its astringent leaves used in salads. Leaves are pinnate. Flowers are produced in spring and early summer. The fruit is a siliqua, up to 2 cm long, slightly curved; with seeds in two rows on each side of the septum. Note: It is not a good idea to eat cress from creeks unless you know the water is very clean. Cultivated cress is usually available.
Photo: Robert Whyte