Fennel. You don't see the bulbs very often in Greek dishes, but wild fennel, which grows everywhere, is another story.
It grows everywhere in Greece and is a key anise-y flavouring in dolmades and other dishes (often replacing its cousin, dill). The ferny leaves are an essential ingredient in dishes such as marathopita and yahnera. An abundance of wild fennel on the east coast of Attica gave its name to the town and site of the famous Greek victory over the Persians in 490 BC, that would go on to give its name to the 26 mile race that replicates the run of Pheidippides who brought the good news back to Athens
γύρη του μάραθου (gyri tou marathou): fennel pollen
σπόρους μάραθου (sporous marathou): fennel seeds
Images by fragrantica, maxipixel