Biology Reference
In-Depth Information
Fig. 2.6
Spiranthes lucida
and
Augochlorella aurata.
(
a
) Lateral view of flower with part of peri-
anth removed. (
b
) Bee removing nectar, showing the position of head and mouthparts. (
c
) Lateral
view of flower after removal of the pollinarium and head of
A. aurata
with pollinarium attached to
the clypeus (forehead), scale bar = 5 mm.
an
anther,
cl
callus,
cr
cardo,
ga
galea,
ne
nectar,
po
pollinia,
sg
stigma,
si
stipes,
vs
viscidium. After Catling (
1983c
),
©
2008 of NCR Canada.
Reproduced with permission
carried pollinaria of
S. lucida
.
A. aurata
usually visited only a single flower in each
inflorescence, even though the spikes normally bore a number of fully open blooms.
When visits to a second adjacent flower occurred, they always involved flight. In no
case did the bee begin its exploration on the lowermost open flower. Compared to
Bombus
, halictine visits to a spike were less systematic and involved much less
crawling and fewer flower visits.
Other species of
Spiranthes
, particularly taxa having relatively small, amply-
distended flowers, often with small viscidia and pollinia, are also sometimes pollinated
by halictines (e.g.,
S. casii
var.
casii
,
S. lacera
var.
lacera
,
S. lacera
var.
gracilis
,
S. tuberosa
) (Tables
2.3
,
2.5
,
2.9
) (Stevenson
1973
; Catling
1980b, 1983c
). The pollinia
of
S. casii
var.
casii
are occasionally found attached between the compound eyes of
Lasioglossum versans
(Lovell) [=
Dialictus versans
(Lovell)] (Catling
1983c
).
However, this is probably abnormal, and except for
S. lucida
it is likely that halictines
usually enter the flowers of
Spiranthes
upside down in order to reach the nectar at the
base of the floral tube (Catling
1980b, 1983c
). The viscidium is then attached to the
underside of the prementum or to the ventral edges of the stipes. Catling (
1980b,
1983c
) observed a
L. imitatum
(=
Dialictus immitatus
) pollinating
S. lacera
var.
lacera
in this manner, but considered it a rare event.
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