Popped kernels of popcorn come in 2 shapes, butterfly and what?

Popped kernels of popcorn come in two shapes, butterfly and mushroom.

Butterfly popcorn, also called snowflake popcorn, has an irregular outline with several protruding wings. It is the shape most people recognize from cinemas and home popcorn makers. Mushroom popcorn expands into a compact, rounded ball with few or no wings, giving it a shape reminiscent of a mushroom cap.

The difference comes from how the kernel’s hull and starchy interior split under heat and steam pressure. Popcorn is a special type of corn whose hard outer shell traps moisture. When heated, the water becomes steam, pressure builds, and the softened starch bursts outward as the hull ruptures.

Mushroom flakes are sturdier and less likely to crumble, so commercial producers often use them for caramel corn, chocolate-coated popcorn, and other heavily flavored snacks. Butterfly flakes are lighter and more delicate, with more surface area for butter or seasoning. A single cob can produce both shapes, although breeders have developed varieties that strongly favor one form.