Abstract

CAMINA, Julia L. et al. Spatial and temporal distribution of floral rewards within the caPitula: the caSe of hyaliS argentea (aSteraceae). Bol. Soc. Argent. Bot. [online]. 2019, vol.54, n.1, pp.1-5. ISSN 1851-2372.

Background and aims: Differential resource allocation to attraction, reward, and sexual functions has been observed at capitula level of derived species of Astera-ceae. Heterogamous capitula contain a combination of pistillate, staminate or sterile and perfect forets, thus rewarding and sexual functions are performed by different kinds of forets and at different times. Such spatial and temporal distribution of re-wards within the capitula is not as clearly established in species with homogamous capitula, where all forets are perfect and produce pollen and nectar. We evaluated the spatial and temporal distribution of foral rewards in homogamous capitula of Hyalis argentea. M&M: We compared the foral phenology, the number of pollen grains and nectar volume and concentration between ray and disk forets, and registered the foraging behaviour of foral visitors. Results: Capitula have a centripetal and alternate fowering pattern and they were visited by bees, ants, butterfies, moths, beetles and thrips, but pollinated mainly by Apis mellifera. We did not fnd a temporal pattern in the offer of rewards within the capitula, but we do fnd a spatial pattern in nectar volume increasing from outer to inner forets. Conclusions: This spatial variability in nectar quantity could impact pollinator behav-ior and thus enhance outcrossing likelihoods improving sexual reproduction in this self-incompatible species.

Keywords : Asteraceae, capitulum maturation, Hyalis argentea, nectar, pollen..

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