
Star anise is the star-shaped dried fruit of the illicium tree, an aromatic spice with a strong anise scent.
Ground star anise is faster and cloudier, a pinch at a time. Aniseed carries the same anethole and less warmth. A dash of pastis or another anise liqueur brings the aroma and alcohol, which suits a cold drink where infusion is not possible.
Japanese star anise
Illicium anisatum: similar in appearance and poisonous. It is not sold as food, but the resemblance is close enough that star anise should come from a grocery supplier and not from the craft aisle.
Aniseed
An entirely different plant, an umbellifer, sharing anethole — which is why both taste of anise. Aniseed is sweeter and plainer, with none of the woody spice around it, so a syrup made on it comes out simpler and less warming.
Whole stars keep for months sealed and dark, and hold their aroma far better than the ground spice. A star that has lost its smell has nothing left to give a syrup.