What is (a) A pod which divides circularly into an upper and lower half, of which the former acts as a kind of lid, as in the pimpernel and purslane. (b) The theca of mosses called?

pyxidium — (a) A pod which divides circularly into an upper and lower half, of which the former acts as a kind of lid, as in the pimpernel and purslane. (b) The theca of mosses. (Webster's 1913.)

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