growth ring PO:0004514 annual ring (narrow) A portion of secondary xylem (PO:0005848) that has as parts a single layer of early wood (PO:0004515) and a single layer of late wood (PO:0004516) from the same growth season and is part of a shoot axis (PO:0025029) or root (PO:0009005). anillo de crecimiento (Spanish, exact) 年輪（＝annual ring) (Japanese, exact) Appears as a ring in a transverse section of plant axis (PO:0025004). May be an annual ring (one growth ring per year) or a false annual ring (more or less than one growth ring per year). growth layer (exact) false annual ring (narrow) tree ring (narrow) plant_anatomy secondary xylem