Patterns of fruit and seed set within inflorescences of Pancratium maritimum (Amaryllidaceae): nonuniform pollination, resource limitation, or architectural effects?

We investigated patterns of fruit and seed production on inflorescences of a population of Pancratium maritimum in northwest Spain over a 2-yr period. Initial findings showed that the earliest opening flowers on an inflorescence are more likely to set fruit and produce more seeds than later opening...

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Bibliographic Details
Published in:American journal of botany 2000-04, Vol.87 (4), p.493-501
Main Authors: Medrano, Monica, Guitian, Pablo, Guitian, Javier
Format: Article
Language:English
Subjects:
Amaryllidaceae
architectural effects
Architecture
floral variation
Flowers
Flowers & plants
fruit and seed production
Fruit set
Fruits
Inflorescences
Pancratium maritimum
Plants
Pollen
pollen limitation
Pollination
Reproductive Biology
Resource allocation
Seed production
Seed set
Seeds
Spain
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Summary:We investigated patterns of fruit and seed production on inflorescences of a population of Pancratium maritimum in northwest Spain over a 2-yr period. Initial findings showed that the earliest opening flowers on an inflorescence are more likely to set fruit and produce more seeds than later opening flowers and that this pattern is maintained throughout the flowering season. Supplementary pollination and flower-removal experiments were performed to investigate whether the observed pattern is attributable (a) to variation in pollen receipt, (b) to sequestration of resources by the earliest flowers on an inflorescence, and/or (c) to "architectural" limitations on the fruit/seed production of later flowers. Supplementary pollination did not improve fruit or seed production by late flowers in either of the 2 yr of study. In flower-removal experiments, the remaining flowers showed improved fruit set and mean number of seeds per flower, by comparison with flowers in the same position on control inflorescences. When all flowers except the latest third were removed, these showed fruit set and seed production similar to those of early flowers on control inflorescences. These results strongly suggest that the observed within-inflorescence patterns of fruit and seed production in P. maritimum are mainly attributable to competition for resources (i.e., explanation b), though other adaptive explanations cannot be ruled out.
ISSN:0002-9122
1537-2197
DOI:10.2307/2656592