Rb. Primack et al., COSTS OF REPRODUCTION IN THE PINK LADYS SLIPPER ORCHID (CYPRIPEDIUM ACAULE) - DEFOLIATION, INCREASED FRUIT PRODUCTION, AND FIRE, American journal of botany, 81(9), 1994, pp. 1083-1090
An earlier experiment with the pink lady's slipper orchid demonstrated
that plant leaf area was lowered only after successive years of incre
ased fruit production. This result suggested that the cost of reproduc
tion was small in relation to the energy budget of the plant. To test
this idea, plants were subjected to experimental hand-pollination trea
tments to increase fruit set as well as leaf removal treatments to dec
rease the energy budget of plants. Changes in plant size in years 2 an
d 3 and, to some extent, rate of flowering, were determined by a combi
nation of initial plant size, leaf removal treatments in year 1, fruit
production in year 1, and damage from an unplanned fire in year 2. Pl
ants that had both leaves removed and produced a fruit in 1987 decreas
ed in size in the following 2 years in comparison with other treatment
groups. The cost of fruit production was not apparent in plants that
had only one or no leaves removed. Plants apparently have to be put in
to severe physiological stress in order for a cost of reproduction to
appear in the following year. The cost of producing one fruit was a de
cline of plant size in the following year of 30 cm(2), which is very s
imilar to our previous experiment using a different design. An additio
nal experiment failed to find evidence that these plants increase thei
r photosynthetic rate to compensate for the loss of leaves or the cost
of maturing fruit. Published experiments in both the greenhouse and t
he field that failed to find a cost of reproduction should be reevalua
ted in terms of the intensity of treatment imposed and the overall ene
rgy budget of the plant in field situations.