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While most hypotheses purport that leaf driptips facilitate drying of the leaf surface through water removal aft rainfall (Richards 1952), one other possible function of driptips is to reduce the drop size of leaf runoff and thereb abate soil erosion under a plant (Williamson 1981). And the ecological distribution of phenotypic traits often provid evidence to evaluate such alternate hypotheses.

Within wet tropical forests relative humidity decreases from ground level to the canopy, so evaporation potential is greatest in the canopy and lowest at the soil surface. Consequently, the rate of post rainfall leaf drying should be an increasing function of leaf height. If driptips function in water removal to facilitate leaf drying, then they should be well developed in the lower plant strata and poorly developed in the canopy. However, if driptips function to reduce drop size, they should be poorly developed in ground stratum plants because …