Platanthera orbiculata (Large Round-leaved Orchid)
|Also known as:||Lesser Round-leaved Orchid|
|Habitat:||part shade, shade; coniferous bogs and swamps, moist upland pine woods|
|Bloom season:||July - August|
|Plant height:||8 to 28 inches|
|Wetland Indicator Status:||GP: FAC MW: FAC NCNE: FAC|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Open raceme on sturdy flower stalk of 6 to 33 green and white flowers about 1 inch long. A squarish upper sepal forms a hood over the 2 creamy pollen sacs, 2 oval-elliptic lateral petals spread out and point up, 2 larger oval sepals spread out to the sides. A long narrow tapered lower lip falls straight down, with a long slender spur, thickest at tip, running parallel to the ovary.
Leaves and stem:
Two opposite leaves at the base, nearly flattened against the ground, oval to nearly round, 2½ to 6 inches long, 1¼ to 6 inches wide with fine parallel veins and a more prominent central vein. 1 to 6 bract-like leaves are scattered along the upper part of the smooth stem.
Rarely in dense populations but scattered over an area, this species can be confused with Hooker's orchid, P. hookeri, but the latter has no bracts along the stem and the flower spur is tapered and narrowest at the tip. Large Round-leaved Orchid sometimes goes by Habenaria orbiculata (as in Newcomb's and Peterson's field guides), but genus Habenaria is now widely considered restricted to the tropical species and Platanthera the temperate zone species.
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Photos courtesy Peter M. Dziuk, taken in Chippewa National Forest near Akeley in Hubbard/Cass counties
Have you seen this plant in Minnesota, or have any other comments about it?