Subtribes Goodyerinae and Cranichidinae - The Pollination Biology of North American Orchids: North of Florida and Mexico - page 8

Table 1.2 2ESULTSFOROPENPOLLINATED;MEANRANGE=ANDEXPERIMENTALTREATMENTSONFOURSPECIES
of Goodyera enclosed in nylon net (percentage capsule set/percentage fertile seed [median (range)])
(Kallunki 1981 )
Variables G. oblongifolia G. pubescens G. repens G. tesselata

Source of plants Michigan Wisconsin,

Rhode
Island

Michigan Michigan

Open pollinated a
Flowers visited (%)

49.8 (3-84) 86 50.5 (3-97)

Flowers pollinated (%) 44.2 (3-66) 79 48.8 (3-96)

41.0 (2-84)
Unmanipulated, caged 0 0 0 0
Pollinarium removed, caged 0 0 0 0
Selfed 100/40 (2-87) 90/77 (12-94) 88/36 (6-88) 86/88 (38-94)
Cross-pollinated 92/60 (0-93) 94/64.5 (8-92) 100/63.5 (0-92) 100/79 (40-97)
a Means and range of means for G. oblongifolia and G. tesselata and the means of one population
for G. repens
b Kallunki ( 1976 )

Fruit set (%) 49.8 (8-70) 49 (76) b

Agamospermy has also been suggested. Leavitt ( 1901 ) reported polyembryonic
seeds in G. tesselata and G. pubescens . Ackerman ( 1975 ) also found a few polyem-
bryonic seeds in some highly fertile capsules of G. oblongifolia , but embryological
studies are needed to determine whether these were produced by cleavage of the
FERTILIZEDZYGOTEORWEREADVENTITIOUSANDASEXUALINORIGIN4HEFORMERINTERPRETA-
tion is favored by the fact that there were never more than two embryos, and these
were always partially fused.
Kallunki ( 1981 HASCONDUCTEDSYSTEMATICEXPERIMENTALPOLLINATIONSONCAGED
plants of all four species collected from the wild. Each was capable of producing
seed with embryos when artificially self- or cross-pollinated, but no autogamy or
agamospermy was found (Table 1.2 ). Kipping ( 1971 ), Stevenson ( 1973 ), Ackerman
( 1975 ), and Kallunki ( 1976 ) also observed no conclusive evidence for either autog-
amy or agamospermy in our species.
In Kallunki's ( 1981 EXPERIMENTSOUTCROSSEDANDSELFEDPLANTSOFTENDIFFEREDIN
capsule and seed production (Table 1.2 ), but none of the differences were statisti-
cally significant. In addition, although Ackerman ( 1975 ) reported average seed
fertility in selfed plants to be somewhat lower than that in naturally pollinated
plants, fertility remained high. There has, therefore, been little to no selection for
self-incompatibility barriers in these species. Mechanisms for the promotion of
outcrossing are nevertheless present (see below), and Goodyera may be said to
process a clonal outbreeding system. For a summary of the advantages and disad-
vantages of this system, see the discussion in the section on Isotria verticillata
(Chap. 9) and (Mehrhoff 1983 , p. 1451).
%XPERIMENTALCROSSESBETWEENANYTWOOFTHEFOURSPECIESOF Goodyera also
produced fertile seed (Table 1.3 ) (Kallunki 1981 ), but intraspecific crosses usually
produced a higher median percentage of fertile seeds than interspecific crosses
(Kallunki 1981 ). This suggests that some degree of incompatibility may be present,
but interspecific fertility levels remained high in all cases (Table 1.3 ). Goodyera