It is usually found in metaxylem tracheids and vessels.经常在木质部管胞和导管中发现.Exarch Denoting a stele in which the metaxylem develops to the inside of the protoxylem.外始式:指后生木质部在原生木质部之内的中柱类型....

n.后生木质部...

metaxylem的音标：metaxylem的英式发音音标为：[metə'zaɪləm]metaxylem的美式发音音标为：[ˌmetə'zaɪlem]...