ï~~2006
THE MICHIGAN BOTANIST
193
TWO RECORDS OF ACHLOROPHYLLOUS
CYPRIPEDIUMACAULE FROM WISCONSIN
Matt Bushman
U.S. Forest Service - Chequamegon-Nicolet National Forest
Great Divide District
10650 Nyman Ave.
Hayward, WI 54843
715-634-4821
[email protected]
The pink lady's slipper orchid (Cypripedium acaule Aiton.) is one of the more
common orchid species in the Great Lakes region, occurring in habitats ranging
from dry sandy upland woods under mixed oaks, pines, or aspens to lowland
bogs amidst sphagnum moss and beneath cedar, spruce, or tamarack (Voss, 1972;
Luer 1975; Case, 1987). The plant also ranges over much of eastern North America (Case, 1987; Cribb, 1997). Variants of the plant have been recorded throughout its range, including plants with two flowers per inflorescence and a white
flowered variant (Cribb, 1997). The white flowered variant of the pink lady's
slipper (f. albiflora Rand & Redfield) is a rare find and typically occurs in the
northeastern part of the plant's range (Luer, 1975). This variant is not a true albino or achlorophyllous plant because it contains chlorophyll and derives most
of its energy through photosynthesis. Achlorophyllous plants are thought to lack
chlorophyll and other pigments that are associated with photosynthesis (Cummings & Welschmeyer, 1998). However, Cummings and Welschmeyer (1998)
found in their study of ten apparent achlorophyllous plant species, representing
four families (Lennoaceae, Monotropaceae, Orchidaceae, and Orobanchaceae),
that chlorophyll and other chlorophyll-related pigments were present although,
at dramatically reduced levels. Although no previous record of a seemingly
achlorophyllous pink lady's slipper is known (Fred Case, personal communication, 20 October 2005), the purpose of this article is to announce the discovery
of two separate occurrences of apparent achlorophyllous variants of pink lady's
slipper in Wisconsin.
Achlorophyllous orchids demonstrate an apparent absence of chlorophyll.
Rather than harnessing their energy via photosynthesis, these plants are theorized to be mycotrophic which means that they parasitize mycorrhizal fungi for
nutrients and carbon compounds (Furman & Trappe, 1971). The parasitized
fungi, in turn, gain their nutrients and compounds from external sources such as
photosynthesizing green plants or from the soil or decomposing organic matter
and therefore act as a bridge between a source of nutrients and the apparent
achlorophyllous plant (Furman & Trappe, 1971). A non-orchid example of this
relationship is shown in a study conducted by Bjorkman (1960) on Monotropa
hypopitys. Bjorkman (1960) demonstrated that Monotropa shared mycorrhizal
fungi with nearby trees and that nutrient materials passed from the trees, through
