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U.S. Forest Service

Plant of the Week

Platanthera obtusata range map. Platanthera obtusata range map. USDA PLANTS Database.

Blunt-leaf Orchid flowers. Blunt-leaf orchid flowers. Photo courtesy Wikimedia Commons.

Blunt-leaf Orchid plant. Blunt-leaf orchid plant. Photo courtesy Wikimedia Commons.

Blunt-leaf Orchid plants. Blunt-leaf orchid plants. Photo courtesy Wikimedia Commons.

Blunt-leaf Orchid (Platanthera obtusata (Bands ex Pursh) Lindley)

By Mark Jaunzems

This is a true circum-boreal or northern plant that ranges all across the arctic regions of Asia, Europe, and North America. In the United States, the blunt-leaf orchid occurs in the Rocky Mountains, along the northern tier of states that border Canada and into Alaska. Another and rarer subspecies of this orchid occurs scattered across the northern portions of Asia and in Europe in northern Scandinavia. (Hulten, 1968)

Blunt-leaf orchid grows in wooded bogs and evergreen forests in the southern part of its range but in the far north it is more widespread and cosmopolitan and can grow in open heathlands or birch-aspen forest. Sometimes it is the only flowering plant visible in the mossy coniferous understory of some white cedar-balsam fir-black spruce swamps. In the northern tier of U.S. states this species can be fairly common and it serves as an indicator of other orchid species, such as calypso (Calypso bulbosa), round-leaved orchid (Amerorchis rotundifolia) , the rattlesnake plantains (Goodyera spp.), and the twayblades (Listera spp.) that may share the same habitats (Case, 1997).

This species has a diminutive flower that is just 1/8 inch to 1/4 inch long with several flowers on a single stalk that is only a few inches tall. Like many orchids this plant has interesting pollination ecology with small moths and mosquitoes. These insects are first attracted by the nectar or fragrance produced by this species. Many orchids use a pollen packet or pollinia for pollination so when a small insect visits one of these plants the pollinia becomes attached to the insect. If the insect finds another orchid the pollen drops off at that time. The pollinia produced by the orchid can be almost as large as a mosquito head; which, as you can imagine can interfere and slow down its flying (Thein, L. B. and F. Utech, 1970).

Blunt leaf orchid blooms in mid-summer around the time that fireweed (Epilobium angustifolium) starts flowering which can be from late June to early August depending on what part of the plants range one is located. Although this plant is not large or spectacular, it is worth taking a look at (Figure 2). Also, its wetland habitat is important to protect for many reasons and include the fact that it often grows together with several other orchids, plants, and at least one species of lichen which are under state and or federal protection.

For More Information

  • PLANTS Profile - Platanthera obtusata, Blunt-leaf orchid
  • Case, F.W. Jr. 1997. Revised Edition. Orchids of the Western Great Lakes Region. Cranbrook Institute of Science, Bloomfield Hills, Michigan, United States.
  • Hulten, E. 1968. Flora of Alaska. Stanford University Press, Stanford, California, United States.
  • Thein, L. B. and F. Utech. 1970. The mode of Pollination in Habinaria (Platanthera) obtusata. American Journal of Botany 57(9) 1031-1035.