Pronunciation: sfi- ' näp-s ə d
Function: noun
Etymology: ultimately from Greek sph ē n wedge + New Latin -opsis
Date: 1957
: any of a class or division (Sphenopsida or Sphenophyta) of primitive vascular plants characterized by jointed ribbed stems, small leaves usually in whorls at distinct stem nodes, and sporangia in sporangiophores and made up of the horsetails and extinct related forms