Biology Reference
In-Depth Information
Fig. 8.3
Calopogon tuberosus
. (
a
) Flower, front view with lip erect, scale bar = 5 mm; (
b
) Flower,
front view with lip depressed, scale bar = 5 mm; (
c
) Apex of column, scale bar = 2.5 mm.
an
anther,
ri
ridge,
ro
rostellum,
sg
stigma
C. tuberosus
develops a variable number of non-resupinate flowers in 1 (-3)
loose, terminal, scapose raceme(s) (Table
8.1
). Flower color is highly inconstant
and ranges from pale pink or occasionally white to deep magenta (Heinrich
1975
;
Luer
1975
; Case
1987
; Boland and Scott
1991
; Smith
1993
). Firmage and Cole
(
1988
) report fewer flowers per inflorescence for populations in Maine, the lower
numbers purportedly a response to a cooler climate. The lateral sepals are reflexed
distally. The lip is erect and includes two small and obscure, basal lateral lobes and
a linear middle lobe with a broadly winged, obtuse apex (Fig.
8.3a
) (Luer
1975
). Its
ventral surface is densely bearded with short, ultraviolet absorbing, filiform to clav-
ate bristles arranged in rows (Case
1987
; Smith
1993
). The column is incurved and
widely winged at its tip (Fig.
8.3c
). An incumbant, terminal anther produces masses
of tetrads in two pairs of soft pollinia. The stigma is perpendicular to the column
and proximal to the anther; a rostellum is usually present, but a viscidium is absent
(Fig.
8.3c
) (Stoutamire
1971
; Sheviak and Catling
2002c
). The absence of a vis-
cidium and the occurrence of loosely formed, friable pollen masses in all three
orchids may not represent a primitive condition but may, as in
Cypripedium
, be an
adaptation to pollination by hairy insects (Stoutamire
1971
).
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