 Like other ferns , members of the Marsileaceae produce spores , but not seeds when they reproduce . Unlike other ferns , the spores in this family are produced inside sporocarps . These are hairy , short @-@ stalked , bean @-@ shaped structures usually 3 to 8 mm in diameter with a hardened outer covering . This outer covering is tough and resistant to drying out , allowing the spores inside to survive unfavorable conditions such as winter frost or summer desiccation . Despite this toughness , the sporocarps will open readily in water if conditions are favorable , and specimens have been successfully germinated after being stored for more than 130 years . Each growing season , only one sporocarp typically develops per node along the rhizome near the base of the other leaf @-@ stalks , though in some species of Marsilea there may be two or occasionally as many as twenty . The resemblance of the sporocarps to peppercorns gives the family its common name of pepperwort . 
