The White Bog Orchid, Platanthera dilatata, has three varieties, though these varieties are not immediately evident to the casual observer, since they involve primarily the length of the spur and that is often hidden by the flowers themselves or by the bract on the stem of the flower. This difference may seem of little account and not sufficient ground for considering these to be different varieties, but as Paul Martin Brown points out in his Wild Orchids of the Pacific Northwest and Canadian Rockies, this difference in spur length as well as the fact that they have different ranges "may be related to specific pollinators."
The ranges of these three varieties overlap a great deal. We know several areas where two varieties or even all three varieties can be found, but very seldom are the different varieties found growing intermixed with one another. They all have the same fragrance, so strong that the whole area will be perfumed on a warm and still day, so if the difference does indicate different pollinators, one would think that the pollinators are at least the same kind of insect, perhaps butterflies or moths., and indeed we have seen butterflies feeding from these flowers on several different occasions and in different locations.
The variety with the shortest spur is Platanthera dilatata var. albiflora. This variety is not as common as the next, but we have found it fairly frequently. Where found it seems to be abundant. It is this variety which is believed to hybridize most easily with different species of the green Platantheras.
The second variety is Platanthera dilatata var. dilatata, which has a spur that is about the same length as the lip. This variety is by far the most common and we have found it growing all over the Pacific Northwest, often with Platanthera stricta and sometimes by the thousands in every wet area.
The third variety is, in our experience, the rarest. It has a spur that is much longer than the lip and for that reason also more noticeable than the spurs on the other varieties. Though we have made a point of looking for this variety we have found it in only a few widely separated locations.
All three varieties are prone to having flowers in which the lip is caught in the "hood" formed by the petals and sepals, so that the flowers are not fully open. Variety dilatata seems most prone to this, and we have found flower spikes on which very few of the flowers are fully opened.
One other variation has to do with the shape of the lip which in all the varieties is "dilated" (broadened) at the base. Very often in varieties albiflora and dilatata this "dilation" is so sharp that the base of the lip looks almost square. We have never this in variety leucostachys.
Note: these notes are to be taken only as observations and not as having any scientific authority.