Fred, the contributor of today’s photographs, notes:
This is an impression of Castanea sativa (German: Esskastanie – “ess” meaning “eat”) which can be found in large quantities at this time of year in the forests of southern Germany … They look great and taste really well baked or roasted!
Spanish chestnut or sweet chestnut is a tree with a long human-related history. Thought to be historically distributed in southeast Europe and Asia Minor, its many uses led it to be cultivated (and naturalized) throughout much of Europe and northern Africa over the span of three thousand years. Its cultivation in North America has been restricted as it is susceptible to chestnut blight, though this is not necessarily the case for trees grown in Europe (source).
The Plants for a Future database goes into detail on the economic botany of this species: Castanea sativa. As alluded to by Fred, the plant is primarily grown for its edible nuts. When roasted, the nuts can incite people to sing holiday carols (I tried to roast some last year, but the first attempt wasn’t too successful – better to do it immediately upon purchase of the nuts rather than waiting a couple weeks was the lesson learned). The nuts are also ground into a gluten-free flour, used as a coffee substitute or used to flavour beer (source: Wikipedia – also includes more photographs of the species).
I found the chestnut consumption data via the Small Farm Center at UC Davis to be rather interesting. The per capita consumption in China of chestnuts is roughly 900g / person (2lb.), double the per capita consumption in Europe at 450g / person (1lb.). Lagging far behind is the consumption in the US – 22.5g / person (1/20 of a lb.), suggesting that what is a seasonal treat for North Americans is much more widely used as a food in China and Europe.