iso·etes | \ īˈsōəˌtēz \
Definition of isoetes
1 capitalized : a large widely distributed genus (coextensive with the family Isoetaceae) of fern allies comprising the aquatic or marsh-growing quillworts that have a short buried lobed stem from which arises a tuft of quilt-shaped leaves bearing sporangia in their axils — see isoetales
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