Green Mountain, an old American potato

Green mountain was once one of the most popular main crop potatoes in the USA.  It was introduced in 1878, from a cross of Dunmore and Excelsior.  It is often reported to be a late variety, but behaves more as a mid-season type here.  It is delicious and high yielding, but has almost no disease resistance, so it is a very difficult potato to keep going where there is much disease pressure.  It flowers only briefly, so it is not easy to get much seed from it, but it is possible.