Keys to Nature
Key to the Orchids of the Chicago Region

© Jeffrey R. Hapeman, Cypripedium parviflorum - Keys to Nature Project

Key to the Orchids of the Chicago Region
Bil Alverson and Jennie Kluse, with illustrations by Kathleen Garness
Adapted from a key to the orchids of Wisconsin by Jeffrey R. Hapeman (, with consultation of Mike Homoya's Orchids of Indiana (1993, Indiana University Press) and Fred Case's Orchids of the Western Great Lakes Region (1987, Cranbrook Institute of Science) for additional species that do not occur in Wisconsin. All three publications are excellent resources for learning about the ecology, biogeography, and taxonomy of orchids. More information about Kathy Garness's wonderful orchid illustrations can be found at Special thanks to all those who generously contributed photos and information that make this key possible: John and Jane Balaban, Merel Black, Lisa Culp, Genna Flemming, Jim Fowler, Peter Grube, Jeff Hapeman, E. Haug, Lorne Heshka, Mike Homoya, Hugh H. Iltis, Emmet Judziewicz, R. K. Kupfer, Ken Lange, Mark Larocque, Scott A. Milburn, T. F. Niehaus, Christopher Noll, Marcie O'Conner, Jeffrey S. Pippen, Kenneth Robertson, Paul Rothrock, Rusty Russel, Dan and Karen Tenaglia, and Lowell Urbatsch. We dedicate this work to Fred Case, a remarkable and respected teacher and writer who was passionate about midwestern orchids and their conservation; he passed away at the age of 83 on 12 January 2011.


Key Structure:
1. Leaves absent (or apparently so) at flowering - 2.
1. Leaves present at flowering - 5.

2. Flowers many along a stalk - 3.
2. Flower solitary; leaf thin, grasslike, or sometimes not present at flowering time - Arethusa bulbosa

3. Flower spike arising from a corm, flowers purplish white; leaf remnants may be visible at flowering - 4.
3. Flower spike arising from a coral-like rhizome; plants leafless saprophytes - genus Corallorhiza

4. Flowers spurless; leaf with silvery striped veins - Aplectrum hyemale
4. Flowers with spur longer than the ovary and petiole combined; leaf with purple underside and often spotted on upperside - Tipularia discolor

5. Lip (at least in part) shaped like a cup, pouch, or slipper - 6.
5. Lip not shaped like a cup, pouch, or slipper - 8.

6. Lip shaped like a broad slipper or pouch - genus Cypripedium
6. Lip not slipper-shaped but part of the lip is shaped like an open cup - 7.

7. Leaves at base of plant only, variously marked or scrawled with white lines. Flowers small, white, clustered on a spike - Goodyera pubescens
7. Stem leafy; flowers with a cup-like lip, variously colored with green, white and purple; lip bearing a fleshy projection - Epipactis helleborine

8. Lip bearing a spur-like nectary - 9.
8. Lip lacking a spur-like nectary - 12.

9. 1 or 2 basal leaves - 10.
9. Lip lacking a spur-like nectary - 12.

10.Flowers bicolored (pink or pale purple and white); lip smooth; two basal leaves - Galearis spectabilis
10. Flowers green or greenish-white - 11.

11. Spur shaped like a short pouch, much shorter than the lip; flowers green - Coeloglossum viride
11. Spur elongate, at least as long or longer than lip - genus Platanthera

12. Flowers several to many, held along the flowering stalk or clustered into an "umbrella" at top - 13.
12. Flowers one to few, borne at the end of a stalk or in the axils of the upper leaves - 16.

13. Leaves 1 or 2, relatively broad (typically oval or elliptical in shape); persistent - 14.
13. Leaves 1 to many, relatively narrow (linear or lance-shaped); or if broader then wilting and dying quickly (not persistent) - 15.

14. Leaf one, seemingly attached mid-stem (but actually arising near ground and then clasping the stem); flowers small, green or greenish-white - genus Malaxis
14. Leaves two, at base of plant - genus Liparis

15. Flowers several (3 - 15), relatively large and usually pink, rarely white; lip uppermost, covered with false stamens (pseudostamens) - genus Calopogon
15. Flowers numerous to many (often 15 - 40 or more), small, white or cream-colored, often in conspicuous spirals on the flowering spike - genus Spiranthes

16. Flowers borne in axils of upper leaves - Triphora trianthophora
16. Flowers borne at the end of stalk - 17.

17. Leaf grass-like, arising from base of plant and clasping stem (but may be absent at flowering time) - Arethusa bulbosa
17. Leaf broader, found midway up or higher on stem - 18.

18. Leaves 1 or 2, midway up stem; plus a single, green, leaf-like bract just below the flower - Pogonia ophioglossoides
18. Leaves 5, all clustered in a whorl just below the flower - genus Isotria


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This page was last modified on: Sun, 12 Jun 2011 21:46:21 -0500.