In botany, a dry fruit that opens when ripe. It splits from top to bottom into separate segments known as valves, as in the iris, or forms pores at the top (e.g., poppy), or splits around the circumference, with the top falling off (e.g., pigweed and plantain). The spore-forming organ (see sporophyte) of liverworts and mosses is also called a capsule.

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