Monday, October 1, 2012

Three Varieties of the White Bog Orchid

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.


  1. Hi Ron,
    That is very interesting. I have experienced Platanthera in the US as a very varying genus. A very interesting genus too. Your observations on P. dilatata are quite interesting.
    Also that butterfly seems to have a pollinea (the little yellow object) on its trunk, which hints to the fact that it is indeed the pollinator.

    1. Hello Martin,
      Once again, thanks for commenting. You certainly are correct about the genus Platanthera. Already the genus Piperia with ten species has been separated from Platanthera, though even this is subject to debate, and I would not be surprised at other efforts to break up or further define Platanthera. There are about 40 species in all and ten here in the northwest with four varieties, one subspecies and several natural hybrids.
      The butterflies are interesting, too. There were at least four different butterflies working these flowers when we saw them, three smaller butterflies and one larger Swallowtail. That makes me wonder whether about the whole idea of different pollinators for the different varieties.
      All very interesting and I would love to show you all of these. Not many around here interested in all the minutiae or in being hauled around to see what to me is very interesting.

    2. Hi,
      40 species is a lot. Sounds kinda like the craze with the Ophrys genus in southern Europe.
      I have a book on american orchids and found the fringed Platanthera species to be among the most beautiful orchids, even though I have only seen pictures (I understood, that those are more in the midwest to east tho.). The ones I have seen have impressed with their sheer size (1.2m height easily in Wells Grey) and variance. The flowers were really past their season as you remember, so I cannot say much about that.

      Not many here care about orchids either. It is seen as a hobby for geezers and oddballs. But I am enjoying it. Long walks out in the nature. See the beauty of the landscape and the living things. I don't mind being the laughing stock for some, if that is what I get back from a hobby. And that is also why there are clubs for this hobby. In the 3 years since I joined our native orchids society I have learned so much about the plants and made experiences and friends, that I would not want to miss, really.

    3. We feel the same, Martin. It is another excuse to be out hiking and exploring, things we love to do anyway. Nor do we care what people think. The two of us are often found crawling around on the forest floor and get some very strange loos and questions from other hikers.

      The native orchid club here only has about a dozen members and many of them are not very active. I've learned a lot in the club, but we do a lot on our own as well, in fact we almost prefer that, since we are into photography and the others aren't and are always waiting for us.

      I would love to see some of the fringed Platanthera species, but have not had opportunity, though we will probably make a trip to the Michigan-Illinois-Ohio area next summer and I have a contact there who has promised to show me around.