Exam 3 (wood/secondary growth)

Apical vs lateral meristems in plant growth

Apical meristems are found at the tips of roots and shoots, responsible for primary growth, while lateral meristems, such as the vascular cambium and cork cambium, contribute to secondary growth, increasing the thickness of stems and roots.

primary growth

lengthening up (taller) and roots growing further down (deeper)

secondary growth

widening (girth) and spreading out in the roots

what does vascular cambium produce

Vascular cambium produces secondary xylem (wood) and secondary phloem, contributing to the plant's growth in thickness.

what does cork cambium produce

Cork cambium produces cork cells that form the outer protective layer of the plant, known as the periderm.

What cells are formed to the inside and outside of the vascular cambium?

The vascular cambium produces secondary xylem (wood) to the inside and secondary phloem to the outside, facilitating the plant's growth in diameter.

primary xylem and phloem formation

Primary xylem and phloem are formed during a plant's primary growth from the procambium located in the apical meristems

secondary xylem and phloem formation

secondary xylem and phloem develop later during secondary growth from the vascular cambium

what tissues form the bark?

Bark consists of ALL the tissues external to the vascular cambium, including secondary phloem and periderm

function of secondary phloem

transports water and organic solutes between roots and leaves 

function of periderm

A suberized layer that protects and insulates underlying tissue

function of lenticels

allow for gas exchange between living stem or root cells and the outside air

heartwood

the dead, inner wood, which often comprises the majority of a stem's cross-section (secondary xylem)

sapwood

the living, outermost portion of a woody stem or branch that still transport materials

softwood

 xylem consists primarily of tracheids; NO fibers or vessel elements. Found in cone-bearing trees (conifers) like pine, spruce, larch, fir and redwood

hardwood

xylem includes tracheids PLUS fibers and vessel elements. Found in dicots native to temperate and tropical regions such as oak, maple, ash, walnut, and hickory

trachieds

water conducting cell in the xylem 

vessel elements

parts of the building blocks of vessels that transport water (pipes)

pines vs oaks

• Pines have softwood (conifers)

• Oaks have hardwood (dicots)

what groups of plantrs show secondary growth?

Conifers and dicots (NOT monocots)

A

pith

C

spring wood

A

summer wood

B

primary xylem

G

phloem

cork cambium

D

vascular cambium

C

secondary xylem

J

cortex

F

xylem ray

E

phloem ray

B

Growth Ring