The European Ash tree (species: Fraxinus excelsior) is a medium size tree native to most of Europe and quite common in Spain where these images were taken. They are relatively common in pasture land in the northern half of Spain where they are used along stone fences and also for poles and firewood using the "Pollarding" method of tree management. The tree in the image above looks as if it has been Pollarded at some point although the branches look as though it has been a number of years since this took place and the tree has been allowed to grow without being trimmed back like many of the others in the area.
The leaves of the European Ash are pinnate compound with 5-11 leaflets. The individual leaflets have serrated margins and measure about 2 inches long and less than 1 inch wide.
The image above shows the newly forming flowers. Below is a picture of the samara like seeds that occur in clusters that look similar to those of the Boxelder maple when they are hanging dry on the tree in the spring.
I found the 1885 illustration below in Wikipedia under a public domain license.
Several of the the images in this post are from the town of "Alameda del Valle" north of Madrid. The word "Alameda" means "a stand of Alamo trees". In this context "Alamo" is the Spanish name of the "Populus nigra" tree.