The fruit of the pepper consists of many minuscule fruits – each about the size of a poppy seed – embedded in the surface of a flower spike that closely resembles a hazel tree catkin. Like "Piper nigrum", the fruits contain the alkaloid piperine, which contributes to their pungency. Another species of long pepper, "Piper retrofractum", is native to Java, Indonesia. The fruits of this plant are often confused with chili peppers, which belong to the genus "Capsicum", originally from the Americas.