Final answer:
Fossil pollen, phytoliths, and starch grains are all examples of microfossils that are used to study past plant diversity and paleoenvironments.
Step-by-step explanation:
Fossil pollen, phytoliths, and starch grains are all examples of microfossils. These microfossils are commonly used by paleobotanists and palynologists to study past plant diversity and paleoenvironments. Pollen grains preserve well in sedimentary records and can provide valuable information about past climate conditions and the presence of specific plant species. Phytoliths are microscopic silica bodies that form in plant cells, and they can help identify different plant species. Starch grains, which are made of carbohydrates, can also provide information about ancient plant diets and food processing.