Flower-level developmental plasticity and mating system in Datura

Reductions in herkogamy with flower positions may be expected in environments with either low pollinator abundance or low nutrients.

To ensure effective pollen transfer, constancy in the morphological expression of traits involved in the spatial disunion of pistil and stamen (herkogamy) along successive branching is necessary. Camargo et al. measured within-plant trend variation of herkogamy-related traits expressed in response to variation in nutrient availability of two populations that differ in pollinator abundance.

Leeuwenberg’s architectural model of Datura stramonium
Leeuwenberg’s architectural model of Datura stramonium. The model consists of a sympodial succession of equivalent sympodial units (metamers), each of which is orthotropic and determinate in its growth. Then, the apex is expected to transform into one flower in each node. A module refers to a portion of an axis (metamer) made up of a single terminal meristem which corresponds to a sympodial unit. Thus, every flower position represents the traits expressed at each sympodial unit, resulting in the sequence of within-individual floral variation observed; in the figure, there is a sequential decrease in flower size and metamer length for the first four positions.

Both populations differ in flower size and had opposite direction in the within-plant variation observed. With decreasing nutrients, a systematic within-plant trend of reduction in flower size, pistil and herkogamy along flower position, increased the probability of self-fertilization in the population of lower pollinator abundance.

Reference List

Camargo, I. D., Nattero, J., Careaga, S. A., & Núñez-Farfán, J. (2017). Flower-level developmental plasticity to nutrient availability in Datura stramonium: implications for the mating system. Annals of Botany, 120(4), 603–615. https://doi.org/10.1093/aob/mcx093