Flower power: its association to bee power and floral functional morphology in papilionate legumes.

CÓRDOBA, S.; COCUCCI A. A.

ANNALS OF BOTANY

OXFORD UNIV PRESS

Año: 2011 vol. 108 p. 919 - 931

0305-7364

Background and aims We tested the hypothesis of filtering of pollinators in papilionate legume flowers according to their ability to exert strength to open flowers to access to rewards. In addition, the interactions with pollen vectors was expected to explain the structural complexity of this flower architecture since operative flower strength may be determined by a combination of morphological traits which form part of an intrafloral functional module. Methods Six papilionate species were studied: Collaea argentina, Desmodium uncinatum, Galactia latisiliqua, Lathyrus odoratus, Spartium junceum and Tipuana tipu. We measured the strength needed to open keels and the strength that pollinators were capable of exerting.  We also measured morphological traits of all petals to reveal which of them could be either mutually correlated or correlated with operative strength and moment of strength and participated in a functional module. Key results We observed that pollinators were capable in all cases of exerting forces higher and often several times higher than that needed to access to floral rewards, and no association could be detected between floral operative strength and strength exerted by the corresponding pollinators. On the other hand, we found strong and significant correlations among morphometric traits and of these with operative strength and moment. This was particularly evident among traits of the keel and the wings, presumably involved in the functioning of the floral moveable mechanism. Conclusions With the exception of the one bee (Apis melifera), flower operative strength does not seem to be acting in pollinator filtering.  On the other hand, strong correlations among certain petal morphometric traits (particularly between the keel and wings) give support to the idea that an intrafloral module is associated to the functioning of the mechanism of these legume flowers. In addition, the highly significant correlations found across petals support the view of functional phenotypic integration transcending the ontogenetic organization of flower structure.