
Green cardamom is a spice — seed-filled pods from a plant in the ginger family.
Eucalyptus-citrus is the note, and warm spice is not the same thing — a cinnamon-and-clove blend fills the slot and changes the drink. Whole pods can be lifted out of an infusion; ground cannot, and it clouds.
Black cardamom
Green cardamom is the pod of Elettaria cardamomum — sweet, floral, eucalyptus and citrus. Black cardamom is a different genus, usually dried over open fire, with a larger, coarser pod and a smoky character. They are not interchangeable: black will make a delicate drink taste of campfire.
The aromatic part is the cluster of hard black seeds inside the pod — 8 to 16 of them — used crushed or ground; the outer husk is largely inert.
Whole pods keep for months in a sealed jar. Ground cardamom fades faster.