Fig. 4

SEM images of vascular tissues in the rhizome. a Unusual vascular bundle structure in transverse section, b grains in bundle sheath fiber in tangential section, c sieve plate in metaphloem in tangential section, d reticulate vessel pits in tangential section. MX metaxylem, MP metaphloem, arrow in a two pairs of metaxylem vessels, arrow in c sieve plates, arrow in d intervascular pit membrane