Why is the fossil record of Caryophyllales limited?

The limited fossil record of the Caryophyllales is primarily due to the fact that the order consists chiefly of herbaceous plants, which are generally less likely to be preserved in the fossil record than woody plants.1

Because of this lack of fossil evidence, scientists must rely on other methods to understand the order's phylogeny and evolutionary history. Researchers primarily use DNA analysis to determine the relationships between living members of the order and to trace their origins within the eudicot flowering plants.1