Insect Pollination of the Endangered Monkey-face Orchid (Platanthera integrilabia) in McMinn County, Tennessee: One Last Glimpse of a Once Common Spectacle

Author:

Lawrence W. Zettler

Additional Authors:

Neeraj S. Ahuja and Thomas M. McInnis, Jr.

Published:

March – 1996

Keywords:

Insect, Pollination, Orchid, Platanthera integrilabia, McMinn County, Tennessee

ABSTRACT
The Monkey-face Orchid, Platanthera integrilabia, was locally common on the Cum- berland Plateau of Kentucky and Tennessee prior to the 1940s, but is currently a C2 candidate for United States protection as an endangered species. Insect pollination of this orchid is described for the first time at the largest remaining population of the species, located in McMinn County, Tennessee, just prior to peak flowering (12-15 August 1992). Despite the orchid having flowers adapted to sphingid moth pollination, three day-flying Lepidoptera (Epargyreus clarus, Papilio glaucus, and P. troilus) carried pollinia on com- pound eyes and were pollinators. Over half of all flowers (624 of 1,096 or 56.9%) set fruit two months after flowering. A mean of 4.7 capsules per inflorescence and 3,433 seeds per capsule was recorded. The survival of P. integrilabia will likely depend on the continued existence of the McMinn County population as a seed source for a vigorous program to reestablish seedlings in suitable habitats.