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of the genus
Argogorytes
, otherwise well-known as the exclusive, pseudocopulatory
pollinators of the fly orchid,
Ophrys insectifera
L. (Nilsson
1981b
).
Tipula
(crane
fly) also visited along with some predatory insects (e.g.,
Chloroperla torrentium
0ICTUSUALLYDESTRUCTIVETOmOWERSANDGENERALLYASSOCIATEDWITHPRIMITIVEBLOSSOM
types (Darwin
1862
; Muller
1873
; Silen
1906
; Heimans and Thijsse
1907
; Faegri
ANDVANDER0IJL
1971
).
Where pollinia were removed, they attached to the head of legitimate pollinators
(Nilsson
1981b
). The pollination mechanism is essentially the same as in
L. cordata
(Nilsson
1981b
), except that, according to Darwin (
1862
), ejection of the rostellar
glue and release of the pollinia do not occur as highly synchronized, independent
events. Rather, the glue contacts both the tips of the pollinia and the insect as it
is ejected, cementing the two together. Also extrafloral nectaries are present in
L. ovata
0ROCTORAND9EO
1972
), and these may prolong foraging of some insects
until the floral nectar is located.
Little information is available on the pollination biology of other North American
species of
Listera
, but certain generalizations have been extrapolated from similari-
ties and differences in floral morphology. Apparently, all species of
Listera
secrete
nectar and have a touch-sensitive column (Melchior and Werdermann
1954-1964
;
Dressler and Dodson
1960
; Dressler
1993
), but only
L. cordata
and
L. ovata
share a
strongly bent labellum, a feature Nilsson (
1981a
) believes to be adaptive for pollina-
tors that crawl between flowers in a raceme. Other North American species, such as
L. convallarioides
(Swartz) Nuttall (Fig.
3.2a
),
L. borealis
Morong,
L. auriculata
Wiegand,
L. caurina
0IPER
L. banksiana
Lindley),
L. australis
Lindley, and
L. smallii
Wiegand, lack such a bend and may be serviced by other pollinators which
fly, rather than crawl, between the flowers (Nilsson
1981a
). Similarly,
L. cordata
and
L. ovata
both have a very short column adapted to insects with short mouthparts. The
long, overarching columns in North American species, such as
L. auriculata
,
L. bore-
alis
, and
L. convallarioides
(compare Figs.
3.1b
and
3.2a
), suggest adaptation to
other groups of pollinators with long mouthparts or long legs (Nilsson
1981a
).
Hapeman (
1996
) photographed a small Dipteran, possibly a fungus gnat, on the
flower of
L. auriculata
in Wisconsin, and Ambs (
2009
) stated, without reference or
further detail, that this orchid might be pollinated by mosquitoes. It must share at least
one common pollinator with
L. convallarioides
as a naturally occurring hybrid of
these species (
L.
×
veltmanii
Case) is known (Case
1964
). Although he observed no
pollinators, Kipping (
1971
) found that 50-70% of the flowers of
L. convallarioides
set fruit over a 2-year period in El Dorado County, California. Like
L cordata
, the
orchid is protandrous (Ramsey
1950
), and despite the differences in floral morphol-
ogy noted above, Kipping believes that nectar secretion, pollinator movements, and
pollinia removal may be similar in the two species.
Other Neottieae
Two additional genera of this tribe,
Cephalanthera
L. C. Richard and
Epipactis
Zinn. occur in North America. These genera are similar in general appearance and
labellar morphology, but differ in column structure (Dressler
1993
). In addition,
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