They are increased by division of the stem or rhizome, or by seeds.
The rhizome, which is the officinal part, though yellow in the recent root, becomes of a dark yellowish-brown by age.
Scales of rhizome and stipes narrow, of firm texture and with thick-walled cells.
Rhizome short with membranous, orange or brown scales having a few bluntish teeth on each edge.
Oleum zingiberis, ...