Kalmar "Family Ophioglossaceae" tana nufin dangin ferns na haraji waɗanda aka fi sani da "harsunan adder" ko "harshen adder's ferns". Wannan dangi ya haɗa da kusan nau'ikan ferns 80 waɗanda aka rarraba su a duk faɗin duniya, da yawa fannin da aka samo suna bayyanar da kasancewar masu sauki, fronds marasa ganuwa da aka bayyana daga rhizome. Sau da yawa fronds suna da tsayi kuma suna da siffar silinda, tare da tsari mai ɗaukar hoto mai suna sporangium wanda yake a gindin frond. Ana samar da spores a jere ɗaya kuma ba a rufe su da wani indusium.Wasu nau'ikan gama gari a cikin dangin Ophioglossaceae sun haɗa da Ophioglossum ("harsunan adder"), Botrychium ("moonworts"), da Helminthostachys. ("ruwan ribbon"). Ana samun waɗannan ferns a wurare masu ɗanɗano ko jika, irin su fadama, ciyayi, da ciyayi masu dausayi, kuma suna taka muhimmiyar rawa a cikin waɗannan muhallin.