Black alder is a tree that likes marshy, boggy areas. Therefore, many trees of the species had grown here before the land of the Royal Łazienki was drained. Today, you can see them near water reservoirs. The bark of the black alder is dark and the wood becomes orange or even red when cut. It is rot resistant. The infructescence of the black alder, made up of many small nuts, resemble cones in appearance.