We don't have synonyms for extravaginal yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are extramarginal and intravaginal.
(adj) :
(botany) Beyond or outside of a sheath; applied to branches springing from buds, which break through the sheath of the subtending leaf, chiefly in grasses.
(adj) :
(botany) Beyond or outside of a sheath; applied to branches springing from buds, which break through the sheath of the subtending leaf, chiefly in grasses.