I went on an outing recently in the "Sierra de Tejado Negro" (the Black Roofs Mountains - all the small towns in this mountain range use black slate for their roofs and thus the name). While on a hike near one of these towns I came across a number of Sweet Chestnut trees (Castanea Sativa). In my previous post on this tree species I did not have any good pictures of the fruit forming. In this post you can get a better idea of what the Chestnut fruits look like as they form. In the picture above you can see that part of the flower is still present even as the fruit forms. I saw this a few times at it looks like one Chestnut can form from each flower "prong".
As you can see in the picture above the forming Chestnuts have some pretty wicked looking spikes. They are sharp but not extremely stiff or hard.
The leaves of the Sweet Chestnut are the key to distinguishing it from the Common Horse Chestnut tree that has a similar fruit but a very different leaf.
Along the trail I came across both old an young trees but none so old as the "Sacred Chestnut of Istan" that I have blogged about in the past.