Are the large clumps formed by generative propagation or by vegetative propagation?
This is a big difference in relation to the normal life expectancy of this species.
Hi Berthold, Cypripediums as many other orchids form big clumps vegetatively. One plant, when it thrives, slowly or faster form several new buds or kids, instead of just one. So called colonies are usually formed by several separate plants that have grown (partly) from seeds.
Epipactis can form big colonies starting just from one plant. They grow usually long underground stolons and the new shoots can be quite far apart from each other.
As you know, many berries need a male plant and a female plant to grow berries.
E.g with cloudberry on some marshes are full of plants, but no berries. That's be cause they have been grown just vegetatively and are just female or male plants.