Sex differential nectar secretion in protandrous Alstroemeria aurea (Alstroemeriaceae): is production altered by pollen removal and receipt?

We examined diurnal and nocturnal nectar secretion across sexual stages in protandrous Alstroemeria aurea, a bumble bee-pollinated herb with long-lived flowers native to the southern Andes We found the following patterns: (1) most nectar was produced diurnally and (2) three times more sugar was secr...

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Bibliographic Details
Published in:American journal of botany 1998-02, Vol.85 (2), p.245-252
Main Authors: Aizen, MA, Basilio, A
Format: Article
Language:English
Subjects:
Alstroemeria aurea
Alstroemeriaceae
Anthers
Botany
bumble bees
Bumblebees
Flowers
Flowers & plants
male and female functions
Nectar
Nectar secretion
Plant reproduction
Plants
plasticity
Pollen
pollen removal and deposition
Pollinating insects
Pollination
protandry
Reproductive Biology
Sugars
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Summary:We examined diurnal and nocturnal nectar secretion across sexual stages in protandrous Alstroemeria aurea, a bumble bee-pollinated herb with long-lived flowers native to the southern Andes We found the following patterns: (1) most nectar was produced diurnally and (2) three times more sugar was secreted during the male than female phase, not only because the male phase lasted longer but also because the rate of nectar production was higher. This 3:1 ratio in nectar production matched the ratio of the minimum number of bumble bee visits required on average to saturate male (pollen removal) vs female (seed set) functions. Standing crop of nectar, on the other hand, did not differ greatly between male- and female-stage flowers left open to visitors, because the high-production male-phase flowers were visited more frequently than female-phase flowers In an experiment concurrent with the repeated nectar sampling of individual flowers over their life-span, we removed pollen from anthers or deposited pollen on stigmas by hand. Neither treatment, designed to mimic effects of visits by Alstroemeria's native bumble bee pollinator, affected nectar production The absence of plasticity in nectar secretion in relation to pollination events may reflect a low cost of nectar production, or may result from developmental constraints related to the evolution of the synchronous protandry that characterizes A aurea.
ISSN:0002-9122
1537-2197
DOI:10.2307/2446312