Tribe Calypsoeae - The Pollination Biology of North American Orchids: North of Florida and Mexico - page 128

Fig. 6.9 Corallorhiza striata . ( a ) Flower, front view; ( b ) Flower, exploded view, scale bars = 2 mm
Autogamy is also present in southern Ontario populations of C. maculata . Based
on examination of stipe rotation, Catling ( 1983 ) reported that self-pollination
occurred in 5-50% of the flowers on each plant with variation evident both within
and among populations. Kipping found fruit set ranging from 51 to 64% in flowers
of C. maculata enclosed in screen cages in El Dorado and Marin Counties, California,
respectively. Insect pollination and probable outcrossing is also recorded for this
species (Kipping 1971 ; Luer 1975 ) and for C. striata var striata (Catling 1983 ;
Freudenstein 1997 ; see below).
The possible development of autogamy within C. odontorhiza , differences in the
mechanism of self-pollination (see below), and a hypothesis of relationships among
the species (Freudenstein 1994b ; Freudenstein and Doyle 1994 ; Senyo and
Freudenstein 2000 ) all suggest that autogamy has originated independently in C.
bentleyi , C. trifida , cleistogamous C. odontorhiza , and C. maculata .
A variety of breeding systems are therefore present in Corallorhiza , including
cleistogamy and autogamy in C. odontorhiza var. odontorhiza (Catling 1983 ) and
C. bentleyi (Freudenstein 1999 ), outcrossing in C. striata (Freudenstein 1997 ) and
C. odontorhiza var. pringlei (Catling 1983 ), and facultative autogamy in C. macu-
lata and possibly C. trifida (Catling 1983 ).
Pollinators and Pollination Mechanisms
Autogamy was long suspected in C. odontorhiza based on the connivent perianth
parts in the majority of plants and the high levels of ovary expansion observed in
natural populations (e.g., Luer 1975 ; Catling 1983 ; Case 1987 ). In his Ontario study,