shaped like a book
• (a.) Having the form of liber, or resembling liber.
Li'bri·form (lī'brĭ*fôrm) adjective [ Liber + -form .] (Botany) Having the form of liber, or resembling liber. Libriform cells , peculiar wood cells which are very slender and relatively thick-walled, and occasionally are furnished with bordered pits.