Secondary xylem forms wide, continuous rings around the pith and vascular cambium located on the outer edge of the xylem produces secondary xylem and phloem tissues. Annual growth rings in temperate woody plants are caused by seasonal dormancy of the cambium layer resulting in larger, more porous spring wood and denser, smaller summer wood cells.

1. Lross section or s yr. od stem Secondary xylem Found as wide, continuous rings around the pith.
Vascular cambium Vascular cambium is located on the outer edge of the xylem and produce
secondary xylem and phloem tissues. The vascular cambium underlies the phloem tissues.
Annual rings Also known as growth rings. The cambium layer in woody plants of temperate
biomes have seasonal dormancy. Growth is most active in spring and tapers in summer, ceasing
in fall. Spring wood typically has larger vessels that are more porous. Summer wood is
comprised of denser, smaller cells. The first cells of the next season's spring wood are produced
next to the smallest summer wood cells of the previous year. Annual growth rings are "caused"
by the alternating pattern of spring and summer wood. Phloem The phloem underlies the bark
and appears as wedge-shaped areas. Cork Cork forms beneath the epidermis and is formed by the
cork cambium. Once cork is present, the epidermis splits and falls off. Cortex The cortex is
located beneath the cork and outside the phloem.