BIOG162 - Module 28 Stems

Covers stems and their structure.

terminal bud

the meristem responsible for primary growth in stems

axillary buds

meristem dispersed on the stem

nodes

where leaves attach on stems

internodes

spaces located between nodes

phyllotaxy

how leaves are arranged

alternate

1 leaf per node

opposite

2 leaves per node

whorled

3+ leaves per node

rosette

when the internode length is short

vascular bundles

clusters of vascular tissues

monocot vascular bundles

randomly distributed vascular bundles, have fundamental tissue

dicot vascular bundles

bundles arranged in a circle, have pith and cortex regions

fundamental tissue

when there is no pith or cortex is in parenchyma

vascular cambium

thin layer of lateral meristem that separates xylem and phloem

the result of cell division in vascular cambium

xylem and phloem are formed through secondary growth, there is more xylem than phloem

secondary growth result

secondary xylem and secondary phloem

large amounts of _____________ creates woody stems

secondary xylem

annual growth ring

generates a ring with each addition of secondary xylem, forms in result of changes in the environment and weather

dendrochronology

the study of tree rings and ring dating

spring xylem

cambium adds more vessel elements; wider

summer xylem

cambium adds more tracheids; narrow

wood rays

form when parenchyma tissue is added

bark

consists of periderm, cortex, and all phoem types

periderm

contains cork cells and a lateral meristem

cork cambium

lateral meristem, produces a parenchyma layer called phelloderms

heartwood

darker, more central, can’t transport water

sapwood

lighter, outer, transports water

lenticels

gaps for potential gas exchange

what forms lenticels?

ruptures in the periderm layers