As with all spices, cardamom's flavor and fragrance come from essential oils that quickly fade if not properly handled. If possible, buy whole cardamom pods.
There are three types of cardamom:Green cardamom - The small pods resemble puffed-up pumpkin seeds. They can easily be slit open with a fingernail and contain clusters of about 10 sticky black seeds, which is the source of most of cardamom's flavor and aroma. The pods may be cooked whole and will soften in heat and liquid, but the casings are not usually consumed whole.
White cardamom - These pale pods are the same ones as green cardamom, but they have been bleached. Most spice buyers say the flavor of white cardamom is milder than the green, but that is also why professional cooks say they don't like to use it.
Availability - Ground cardamom is widely available at supermarkets. Whole cardamom seeds may be at some supermarkets and specialty shops. Green cardamom pods are sold through natural food stores such as Whole Foods Markets; green and black cardamom can be found at specialty spice retailers and at Indian and Middle Eastern groceries.