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U.S. Forest Service

Plant of the Week

Map of the United States and Canada showing states. States are colored green where the species may be found. Range map of Calopogon tuberosus. States are colored green where the species may be found.

Close up of the Calopogon tuberosus flower.Close up of the Tuberous Grass Pink (Calopogon tuberosus). Image by Christopher David Benda.

Group of Calopogon tuberosus.Group of Tuberous Grass Pink (Calopogon tuberosus). Image by Christopher David Benda.

Calopogon tuberosus in its natural habitat.Tuberous Grass Pink (Calopogon tuberosus) in its natural habitat. Image by Christopher David Benda.

Tuberous Grass Pink (Calopogon tuberosus)

By Christopher David Benda

This gorgeous wildflower is called grass pink and it is in the Orchid family (Orchidaceae). The genus name “Calopogon” is Greek and means “beautiful beard.” It refers to the hairlike structures on the upper petal. It has a bulb-like corm that resembles a tuber, hence the name “tuberosus.” The slender grass-like leaves give rise to the name “grass pink.” It is a stunning wildflower.

Flowering stems have one to several flowers and typically several bloom at a time. They range from light pink to magenta, with some flowers being white. There are three spreading sepals and two lower petals, with one above called the upper lip. There are many orange stamen-like structures on the upper lip that attract pollinators. A curved column with the male and female flower parts arches below the upper lip. Flowers bloom from mid-May to July.

The pollination of grass pink is fascinating. Orchid flowers are highly evolved with all kinds of complex interactions occurring between the flowers and their pollinators. Bumblebees land on the upper lip of the flower, and upon landing they are thrown backwards where their backs are dipped in pollen. There is no nectar reward and the bumblebees fly off to another flower to do it again. This apparently works best on newly emerged, naïve bumblebees.

This is one of few orchids that does not have resupinate flowers. Most orchid flowers actually rotate as they develop and appear upside down, that is, the lower lip is placed above; this genus does not.

There are five species of Calopogon in North America and this species is the most widespread. It is mainly a coastal species, but also occurs in the Midwest. It prefers moist places like wet meadows, calcareous fens, and acidic bogs.

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