This is the sterile male organ at the end of the banana bunch. The bunch grows from the female, self-fruiting flower above the male flower. Two species of banana flower are commonly used for cooking, one a green flower, the other purple. The long green flower is better as it does not go brown when cut, whereas the less expensive purple flower discolours very quickly.
To prepare the flower for a sa, lahp or kao poon (a Lao noodle dish), remove the tough, outer petals and any large stamen until the creamy, inside leaves are exposed. Finely slice from the tip across the width of the flower directly into a bowl of water that has a little bit of salt or lime juice added. If using in a soup or stew, simply hand shred the leaves into pieces and immediately add to the pot. Do not use the outside stamen, but the inner ones may be cooked. Banana flower is also a traditional medicine for maternal health care as it encourages lactation. Belgium endive may be substituted.