Corallorhiza odontorhiza (Autumn Coralroot)

Plant Info
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):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: indistinct Cluster type: raceme

[photo of flowers] 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: Leaf attachment: alternate Leaf type: simple

[photo of stems] 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: Fruit type: capsule/pod

[photo of fruit] 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

Photos 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?

Posted by: WCP - Chaska, Carver County
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.

Posted by: Heather - Lone Lake Park, Minnetonka
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.

Posted by: Mary Beth - Maplewood Nature Center, Maplewood, Ramsey County, MN
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!

Posted by: Joe - Dakota County
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.

Posted by: Bill - Afton, Washington Co.
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.

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