Tribe Malaxideae - The Pollination Biology of North American Orchids: North of Florida and Mexico - page 99

The pollination mechanism and a number of pollinators have been reported for
other species. For example, Wallace ( 1974 ) studied the pollination of L. reflexa
2"R,INDLEYINSOUTHERN!USTRALIA4HEPOLLINATORHEREWASANUNIDENTIlEDDIP-
teran in family Sarcophagidae. Attracted by an odor reminiscent of stale egg yolk,
it landed on the labellum and crawled toward the base in search of nectar. A space
between the two-winged column and curved labellum just accommodated the fly.
As it withdrew from the flower, the top of its thorax contacted the rostellum and
received a deposit of glutinous fluid. Continuing its withdrawal, it contacted and
lifted the anther cap, and pollinia were discharged onto the deposit of sticky fluid.
Franzen ( 1990 ) speculated that a similar pollinator might visit L. furcata (Hook f.)
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might also attract members of the Sarcophagidae, which, as the name suggests,
often deposit their eggs on decaying plant or animal material.
Different insect groups are probably involved in the pollination of other mem-
bers of the genus, as already implied by the reported absence of a floral odor in
L. liliifolia. Christensen ( 1994 ), for example, considered small gnats as potential
pollinators of some Liparis species with long racemes and unpleasant smelling, tiny
greenish flowers, and Peterson [in Christensen ( 1994 )] found that Culex mosquitoes
pollinated L. viridiflora (Blume) Lindley grown in a window at Aarhus University
in Denmark. Darwin ( 1862 ) thought that the wings on either side of the entrance to
the stigma in this and some other species might serve as a guide for the insertion of
pollinia, but he observed no pollinators.
Reproductive Success and Limiting Factors
Once they reached a critical, minimal size, most plants at Whigham and O'Neill's
( 1991 ) Maryland site flowered regularly each year producing a more or less constant
number of flowers per inflorescence. However, only 0.0-7.3% of open-pollinated
flowers produced fruit. They attributed this very low level of fruit production to the
combined effects of pollinator limitation; small, dispersed populations; and self-
incompatibility. Asexual reproduction also occurs. Corms, loosely embedded at or
near the surface of the litter layer, are able to reproduce by the production of offsets.
In addition to low levels of fruit production, limiting factors of particular signifi-
cance in the northeastern USA, where this species is becoming scarce, include forest
succession with increased shading; predation by herbivores, particularly deer; and
competition from invasive plant species (e.g., Sheviak 1974 ).
Liparis loeselii (L.) Richard (Loesel's Twayblade or Fen Orchid)
Habitat and Distribution
Also found in Europe, L. loeselii is distributed throughout northeastern North
America from eastern Nova Scotia to Saskatchewan and south to Iowa, Tennesse,