Lecture 28- secondary growth Flashcards
what does the lateral meristem do?
adds thickness to woody plants (secondary growth)
what are the two cambiums the lateral meristem consists of?
vascular cambium
cork cambium
what does the vascular cambium do?
adds layers of secondary xylem and phloem
produces cells in both directions
forms a complete ring
where is the vascular cambium found in the woody stem?
outside the pith and primary xylem and inside the primary phloem and cortex
what does the cork cambium do?
replaces the epidermis with the periderm (thicker and tougher)
what is the periderm?
cell layers of the outer bark
what arises first, the cork cambium or vascular cambium?
vascular cambium
what is the function of vascular rays?
enables lateral transport (originates from vascular cambium)
what happens to the pith after many years of secondary growth?
crushed by secondary xylem
is secondary growth present in both dicots and monocots?
no, only in dicots
what is the difference between early wood and late wood?
late wood has thick cell walls (contributes to stem support)
early wood thin cell walls (to maximize water delivery)
what are the 4 types of wood?
soft wood
hard wood
heart wood
sap wood
what are characteristics of soft wood? (5)
uniform texture
primarily made of tracheids
has a resin canal (helps produce sap)
secondary growth
dead at maturity
what are characteristics of hard wood? (4)
variable texture
dicots
angiosperms
no secondary growth
what are characteristics of heart wood? (2)
non living (not active in transport)
darker color (accumulates stuff)
