golpar (Persian hogweed)
Ground seeds of Persian hogweed, a typically Iranian spice that is bitter, resinous and faintly lemony.
Golpar is the dried seed of Persian hogweed, an umbelliferous plant native to Iran, and is usually sold ground. It smells strong, earthy and resinous and tastes distinctly bitter with a faintly lemony edge, so it is used sparingly. Persian cooks sprinkle it over pomegranate seeds, boiled broad beans, potatoes and soups, and add it to pickled vegetables. It is sometimes mislabeled as angelica seed. It can be found in Persian and Middle Eastern grocery stores, occasionally in Turkish supermarkets, and otherwise by mail order.
Substitute:
There is no real substitute, because no common spice has this combination of bitterness and resinous aroma. A pinch of ground celery seed or a little cumin adds an earthy note, but the dish will taste noticeably different; when in doubt, it is better to leave golpar out.