Calopogon tuberosus (Tuberous Grass-pink)

Plant Info
Also known as:
Family:Orchidaceae (Orchid)
Life cycle:perennial
Habitat:part shade, sun; coniferous swamps, peat bogs, sedge meadows
Bloom season:June - August
Plant height:8 to 21 inches
Wetland Indicator Status:GP: OBL MW: OBL NCNE: OBL
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: irregular Cluster type: raceme

[photo of flowers] A lively raceme of 2 to 12 light (rarely white) to deep pink flowers 1 to 1½ inches across, at the top of a smooth, slender stem, typically opening sequentially from the bottom upwards. Flowers are irregular, 6-parted and atypical to most orchid species, the lip - a modified petal - is situated at the top of the flower rather than the bottom. The lip is generally anvil-shaped, wider than long, with an abruptly inflated triangular tip, rounded or angled on the ends, and a cluster of long, yellow tipped, stamen-like bristles at the constriction point between the tip and neck below, sometimes with a few bristles scattered on the sides of the neck. Above the bristly tip is a circular area on the lip covered in short, stout bristles that are white or yellow with yellow or orange tips. The lip is flanked by two broadly, lance oval sepals, then a pair of somewhat smaller lance-elliptic petals with another single lance-elliptic sepal below. The center column curves down and out just above the lower sepal, stigma embedded at the tip between two flaring flat, rounded lobes (rostellum). 

Leaves and stem: Leaf attachment: alternate Leaf type: simple

[photo of leaves] The single leaf is very long and linear, grass-like, 3¼ to 13½ inches long and typically between 1/10 to just over ½ inch wide, the tip well below the flower cluster.


Tuberous Grass-pink was long considered the only Calopogon species found in Minnesota until Oklahoma Grass-pink (C. oklahomensis) was recognized as a new species in south central US, and subsequent herbarium studies revealed several likely candidates for Minnesota dating back to 1884. While it is more than less accepted as native to the state it is likely long extinct and unlikely to be encountered. Still the possibility exists and while the two are very similar in appearance they can be distinguished on several characteristics. The first would be habitat, C. tuberosa inhabiting wet, moss covered floating mats and fen meadows from the Twin Cities north and C. oklanhomensis on upland mesic prairie or oak savanna. Another characteristic is a shorter leaf in C. tuberosa that typically stays well below the flower cluster where the C. oklanhomensis leaf reaches into the flower cluster. Both species have a modified petal that is the upper lip with a cluster of bright yellow, stamen-like bristles near the tip. But in C. tuberosa, the expanded tip is shorter than wide like an anvil, where C. oklanhomensis is more fiddle-shaped, about as long as wide. Above the cluster of brightly colored bristles found in both species, the shorter bristles in the center of expanded tip in C. tuberosa are often white with yellow to deep orange tips where in C. oklahomensis they are pink.

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More photos

Photos courtesy Peter M. Dziuk, taken on floating sphagnum mats along a lake edge in Aitkin County. Photos courtesy Christopher David Benda taken in Illinois.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Lou - Blaine, Anoka County
on: 2011-05-03 12:13:40

A large colony has been observed over the last 5 years in a bog meadow in Blaine MN

Posted by: Fred - Lake Bemidji State Park
on: 2013-07-04 17:10:33

Found along the Bogwalk in Lake Bemidji State Park on July 2, 2013.

Posted by: Brett W - Otsego
on: 2015-06-27 17:55:13

Saw a lot of these today in Kathio State Park out in a fen.

Posted by: Steve L - Itasca county around the edge of Stumple Lake
on: 2017-06-29 20:16:52

29 June 2017. Found them today. They are just starting to open.

Posted by: Debbie Petersen - Cass County
on: 2018-07-02 20:09:27

Found many in a coniferous swamp southeast of the town of Boy River today.

Posted by: Janie J - Savanna Portage State Park
on: 2019-07-20 13:04:13

At the end of the bog boardwalk there were several in bloom, some with a white top part of the flower. (I would like to share a picture with the moderator, if there is an interest.

Posted by: Mark Basiletti - Black Duck Mn
on: 2023-06-28 10:20:42

Many seen in bog bordering north shore of Anderson Lake.

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