Corallorhiza odontorhiza (Autumn Coralroot)
| Also known as: | Late Coralroot |
|---|---|
| Genus: | Corallorhiza |
| Family: | Orchidaceae (Orchid) |
| Life cycle: | perennial |
| Origin: | native |
| Habitat: | part shade, shade; woods |
| Bloom season: | August - October |
| Plant height: | 5 to 8 inches |
| Wetland Indicator Status: | none |
| MN county distribution (click map to enlarge): |  |
| National distribution (click map to enlarge): |  |
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Detailed Information
Flower: 
![[photo of flowers]](/udata/r9ndp23q/pd/corallorhiza-odontorhiza-30.jpg)
Erect raceme of 7 to 16 tiny, non-descript nodding flowers about 1/8 inch long, on a short flower stalk. The ovary is predominant, greenish to yellow, about ¼ inch long. Petals and sepals are whitish at the base with brown purpling at tips, though white lower lip may fold slightly outward. The flowers of Minnesota's variety do not open and self pollinate within flower (cleistogamous) though the eastern variety does open and pollinates sexually (chasmogamous).
Leaves and stem:
![[photo of stems]](/udata/r9ndp23q/pd/corallorhiza-odontorhiza-26.jpg)
Leaves are reduced to overlapping sheathes from the base. Smooth throughout, stem color is the same as ovaries, greenish to yellow. Stems are unbranched, single to multiple clusters.
Fruit:
![[photo of fruit]](/udata/r9ndp23q/pd/corallorhiza-odontorhiza-47.jpg)
The ovaries develop into hanging capsules, ¼ to 1/3 inch long
Notes:
Perhaps a child only a mother autumn coral-root could appreciate, or those enthralled by the secrets of our native orchids. While early records are infrequent, this species could be just expanding its range westward into Minnesota, or its diminuative stature and late blooming date may have it too commonly passed over. The population in these photos has established itself since the late 1990s. There are 2 recognized varieties of C. odontorhiza: var. pringlei, the eastern species not known to be in Minnesota but recorded in Wisconsin and Iowa has flowers that open fully and resemble those of other coralroot species, and var. odontorhiza, with the flowers described here.
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More photos
Autumn Coralroot plants
a rare opened flower
more plantsPhotos courtesy Peter M. Dziuk, taken on a private residence in Washington County that was formly a production nursery field
Comments
Have you seen this plant in Minnesota, or have any other comments about it?
on: 2011-09-08 00:13:22
Found in two separate locations in the woods at about a 10 degree grade on our heavily wooded lot, under red and white oaks and maples. The plants are growing in groups of about 4-5.
on: 2011-12-09 09:23:42
Found a few clusters in early winter when the plants show up against the snow. Also know of some in eastern Carver County.
on: 2011-12-22 10:10:54
Reported by botanist Scott Milburn during a fall 2011 nature hike at Maplewood Nature Center. Stated as being the first found in Ramsey County. Reported by staff naturalist Oakley Biesanz in the nature center's monthly newsletter, quoting this site for more information on the plant! :) Thank you yet again, Minnesota Wildflowers!
on: 2015-08-19 06:51:01
Found in Miesville Ravine Park in mid-August under a 75% canopy of mixed oaks (bur and pin), sugar maple, basswood, black cherry, ironwood, and red cedar. Shrubs were about 40% canopy cover and consisted of prickly ash, gooseberry, and common buckthorn. The ground layer was sparse to interrupted made up of primarily Pennsylvania sedge. Site was on a northwest facing slope about 15 to 20%. Was in an area of many small and large ravines near a steep bedrock bluff. Soil was sandy. The plants were arranged in one cluster of about 5 stems. Very small--we almost stepped on them before noticing them. The sheath leaves with small, closed, nodding flowers were distinctive. Stems had a dark reddish cast.
on: 2016-08-15 17:00:50
Two plants, each with 2 stems, growing in a European buckthorn thicket in sand. Over story of red and bur oak.
on: 2018-09-11 09:36:44
Found multiple plants in multiple locations in Kandota township. Most plants the inflorescence was cleistogamous as is common with this species. One population had two viable florets. Companion plants include Galearis spectabilis, Quercus macrocarpa, Caulophyllum thalictoides, Betula papyrifera, Urtica spp., etc. No known pollinators have been identified, however seed set is low for chasmogamus plants vs. cleistogamous. More study must be done.
on: 2020-08-23 20:51:38
I believe that I have located 2 clusters on our wooded lake property. I also recently found an Indian pipe. Undisturbed primarily oak woods with pine, poplar, ironwood.
on: 2020-08-30 22:21:54
I found a few small populations of this deep in the middle of the Rock Marsh WMA in Pine County, MN. Perhaps a Pine County record? In fruit today, August 30, 2020. Aspen, Bur oak forests on islands between old river channels of glacial river St. Croix.
on: 2020-09-15 08:48:50
I found a couple of these in Maplewood State Park on 9/13/2020 and notice there are no records of it yet in Otter Tail County. Is there someone I could report it to, so there is a record?
on: 2020-09-15 09:36:24
Micayla, you could contact the DNR's Biological Survey department, but records won't be updated without confirmation.
on: 2022-08-26 15:17:05
We found Autumn Coralroot in SE Rice Co., August 26, 2022. I took a DNR official with me to check it out. Pics available.
on: 2022-09-14 11:46:55
I found a few plants in a mesic hardwood forest along the St. Croix river just north of Taylors Falls in Chisago County.
on: 2023-09-08 19:45:11
Found a couple of spots hiking along LST near Ely's Peak. Pretty cool birthday surprise!