Size-dependent allocation of biomass to ancillary versus flowers of the inflorescences of the epiphyte Tillandsia stricta Soland (Bromeliaceae)

Abstract

The amount of resources invested in reproduction is closely correlated to plant size. However, the increase in reproductive investment is not always proportional to the increase in vegetative growth, as the proportion of plant resources allocated to reproduction can increase, decrease or be maintained along different plant sizes. Although comprising thousand of species, epiphytes are poorly studied in relation to reproductive allocation (RA). We describe the variation in the RA of the epiphytic bromeliad Tillandsia stricta Soland with increasing plant sizes. Our goal is not only to evaluate the RA of the whole inflorescence but also quantify the contribution of ancillary structures in the final RA of this plant species. With increasing sizes of T. stricta the reproductive allocation of biomass to the whole inflorescence decreased significantly along plant sizes from 37% to 12%. Reproductive allocation to ancillary and to flowers decreased respectively from 30% to 9% and 10% to 3%. As leaves are the main source of water and nutrients absorption in atmospheric Tillandsia, the total leaf area and area per leaf were used as indicators of foraging capacity, that also increased with plant size. We discuss these results with respect to the capacity of T. stricta to reproduce in the heterogeneous environment of the canopies.