Isotria verticillata (Muhl. ex Willd.) Raf.

Large Whorled Pogonia

Facts About

Accepted Synonyms: Arethusa verticillata, Pogonia verticillata

Isotria verticillata, commonly called Large Whorled Pogonia, is found throughout the central and eastern United States, from Texas to Maine, and in Ontario. It has a purplish brown stem and 5 leaves which form a whorled ring around the upper part of the stem. The leaves are green on the upper surface, and occasionally greyish blue or green on the bottom surface. It produces 1-2 flowers with purple-brown sepals, yellowish green petals, and a yellow-green to white labellum, which is often striped with purple. It can be distinguished from I. medeoloides by its larger size and its purple, instead of green, sepals. It is known to form extensive clonal groups and can be found in mesic to dry forests and woodlands, and occasionally in bogs.

Isotria verticillata is considered globally secure, but may be rare or vulnerable around the southern, western, and northern edges of its range.


This orchid is pollinated by bees, including Andrena ceanothi, Andrena miranda, Andrena nasonii, Augochlora pura, Lasioglossum cressonii and Nomada sayi which are attracted by the flowers' nectar guides, even though they provides no nectar. The pollinator lands on the flower and enters through the floral tube in search of nectar. The pollinator goes under the anther to the stigma where it gets a sticky substance on its thorax. As the pollinator is leaving the flower it passes by the anther and pollen is then stuck to the sticky substance on the thorax. The pollen is then transferred to the stigma of another flower.

Ecosystem Type

Disturbed habitats, forests, woodlands


Leaf arrangement:
Number of leaves on stem:
  • five
  • six
Form of the labellum:
the labellum is not pouch-like
Labellum outline:
the labellum is lobed
Main color of labellum:
  • blue to purple
  • green to brown
  • white
  • yellow
Nectar spur:
Inflorescence type:
the inflorescence has one flower or a pair of flowers
Labellum characteristics:
the labellum is lobed
Labellum length:
15–25 mm
Sepal length:
34–67 mm
Plant height:
4–40 cm
Show All Characteristics

Native to North America


North American Conservation Status & Distribution

Conservation Status

Select a location to view conservation status:

Conservation and Wetland Status
Global Rank Secure
US Status N/A
Canadian Status Endangered

North America Distribution

Adapted from USDA data