Movement-assisted dichogamy in Atamisquea emarginata (Capparaceae) |
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Authors: | D Medan G Ponessa |
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Institution: | (1) (e-mail: diemedan@mail.retina.ar), Cátedra de Botánica, Facultad de Agronomía de la Universidad de Buenos Aires, Av. San Martín 4453, 1417-Buenos Aires, Argentina., AR;(2) Fundación Miguel Lillo, Miguel Lillo 251, 4000-San Miguel de Tucumán, Argentina., AR |
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Abstract: | Various aspects of the reproductive biology of Atamisquea emarginata Miers ex Hook. et Arn. were studied in a population from Tucumán, northern Argentina. Flowering took place in late (austral)
spring to early summer. The creamy white, entomophilous flowers were protandrous and lasted 3.5–4.5 days. A pleasant odor
along with nectar and pollen attracted 36 mostly diurnal insect species of which 41.7% were Hymenoptera, 38.9% Lepidoptera
and 19.4% Diptera. However, 75% from all recorded species were infrequent, and domestic bees made ca. 94% of all visits. One
halictid bee, one sphecid wasp, one myzinid wasp, four small- to medium-sized butterflies and a hawkmoth completed the set
of relatively frequent insect visitors. Pollen and stigma were presented in the same place within the flower, but interference
was prevented by a movement-assisted, complete dichogamy mechanism in which the bending ability of the gynophore played a
fundamental role. This form of dichogamy was previously unknown in the Capparaceae. In comparison with the known species of
the closely allied genus Capparis L., A. emarginata has diurnal, smaller, longer-lasting flowers, that offer much smaller nectar amounts, and that attract a rather generalized
array of non-hovering visitors, while Capparis behaves as a more crepuscular-biased sphingophile or ornithophile or chiropterophile. Low levels of seed set under bagging
indicates dependence on insect visits and are partly congruent with an earlier report of self-incompatibility in A. emarginata. Pollen tubes arrived to ovules in 90.6% of the inspected flowers. Fruit set of open-pollinated flowers was 43.6%–53.7%.
Ninety-five percent of all ovules were regularly aborted in each fruiting ovary; thus, each fruit contained 1.2 developed
seeds. Full-sized individuals were expected to produce ca. 10,700 potential offspring per year.
Received August 19, 2002; accepted October 8, 2002 Published online: February 7, 2003 |
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Keywords: | : Movement-assisted dichogamy Atamisquea emarginata pollination protandry Capparaceae |
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