Biology Reference
In-Depth Information
took longer to flower than clonal ramets. Nevertheless, a variable but usually high
number of capsules were usually produced (Correll
1978
; Brackley
1985
; Homoya
1993
; Reddoch and Reddoch
1997
). The percentage of flowering rhizomes in each
patch usually ranged from 0 to 8%. However, at 2-4 year intervals the percentage
increased to over 8% and up to 30%. Although rhizomes were no longer connected
to one another, the intermittent large flowerings were synchronized within patches,
between patches, and between populations. Reddoch and Reddoch (
2007
) corre-
LATEDTHISSYNCHRONYWITHTHEOCCURRENCEOFANEXTENDEDWARMDRYPERIODIN-AYOF
the preceding year.
Kallunki (
1981
FOUNDWIDEINTRASPECIlCVARIATIONINFRUITSETINFOURMIXED
open-pollinated populations of
G. tesselata
and
G. oblongifolia
from Michigan
(Table
1.2
). A fruit set of 90% reported by Kipping (
1971
) for a small population of
G. oblongifolia
IN#ALIFORNIAEXTENDSTHERANGEEVENFURTHER+ALLUNKIATTRIBUTEDTHE
variation she observed to differences in the abundance and visibility of
Goodyera
SPECIESTHEPRESENCEORABSENCEOFCOMPETINGSPECIESANDORDIFFERENTIALEXPOSURE
to strong winds and human activity. In any case, mean fruit set values in naturally
pollinated plants of
G. tesselata
,
G. repens
, and
G. oblongifolia
were markedly
lower than in hand-pollinated plants (Table
1.2
), suggesting that pollinator recruit-
ment might be a limiting factor. Flowering plants also produced a higher mean
number of new rhizomatous growths than nonflowering plants (Ackerman
1975
),
implying an absence of resource limitation. Long-term studies are needed, however,
to sort out possible initial differences in plant vigor.
In Ackerman's (
1975
) study of
G. oblongifolia
in California, pollinaria were
REMOVEDFROMOFOPENPOLLINATEDmOWERSANDDEPOSITEDONOFEXPOSED
stigmas. Mature capsules developed in 46% of the flowers. Ackerman considered
the mortality rate, taken as the difference between the number of flowers pollinated
and the number of capsules that matured, to be significant. Intervals between polli-
nation and fertilization and between fertilization and maturation of the capsules
were short. Seeds were sometimes liberated within a few weeks of flowering (Catling
1990
). Although Swamy (
1949
) thought such short intervals represented a primitive
condition, Ackerman (
1975
) believed they were related to mortality rates, repre-
senting a secondary adaptation to environmental conditions.
Wind distribution of the seeds and adaptation to common and widely occurring
pollinators indicate a potential for wide dispersal (Muesebeck et al.
1951
; Ackerman
1975
). Ackerman (
1975
) suggests that the disjunct population structure of
G.
oblongifolia
may reflect this potential. However, Case (
1987
) believes that, at least
in the Great Lakes region, disjunct populations may represent remnants of a once
more widespread distribution fragmented by glaciation.
A number of factors, therefore, appear to contribute to the reproductive success of
one or more species of
Goodyera
(Ackerman
1975
). Seed production is increased by
self-compatibility, clonal growth, aggregation of flowers, nectar production, and adap-
tation to common pollinators; maintenance of genetic variability results from occa-
SIONALOUTCROSSINGPROMOTEDBYPROTANDRYANDHYBRIDIZATIONISRESTRICTEDTOANEXTENT
that permits individual species to maintain their identities; capsule mortality may
be minimized by short maturation time; and the establishment of new populations is
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