Transcript Plant Anatomy

Plant Anatomy
Spikelet
Inflorescence
Culm (stem)
Node (joint)
Internode
Stolon
Leaf
Rhizome
Plant TISSUES
Dermal •
epidermis (“skin” of plant) –
single layer of tightly packed –
cells that covers
& protects plant
Ground •
bulk of plant tissue –
photosynthetic mesophyll, –
storage
Vascular •
transport system in –
shoots & roots
xylem & phloem –
Plant CELL types in plant tissues
Parenchyma •
“typical” plant cells = least specialized –
photosynthetic cells, storage cells –
tissue of leaves, stem, fruit, storage roots –
Collenchyma •
unevenly thickened primary If
walls
I’d –
only
had triplets!
support
–
Sclerenchyma •
very thick, “woody” secondary walls
support
rigid cells that can’t elongate
dead at functional maturity
–
–
–
–
Parenchyma
 Parenchyma cells are unspecialized, thin, flexible & carry out many metabolic
functions

all other cell types in plants develop from parenchyma
Fig. 38.12a
Collenchyma
 Collenchyma cells have thicker primary walls & provide support
 help support without restraining growth
 remain alive in maturity
the strings in celery stalks
are collenchyma
Fig. 38.12b
Collenchyma
Celery
Sclerenchyma
Thick, rigid cell wall •
lignin (wood) –
cannot elongate –
mostly dead at maturity –
Cells for support •
xylem vessels –
xylem tracheids –
fibers –
rope fibers •
sclereids –
nutshells •
seed coats •
grittiness in pears •
Fig. 38.12c
Schlerenchyma
hau – used to make rope
vessel elements
 Xylem


vessel
element
Vascular tissue
move water & minerals up from roots
dead cells at functional maturity
 only cell walls remain
 need empty pipes to efficiently move H2O
 transpirational pull
dead cells
Aaaah…
Structure–Function
again!
tracheids
Fig. 4.9
Fig. 38.13b
Fig. 38.13a
Fig. 4.6
Phloem: food-conducting cells
 carry sugars & nutrients throughout plant
sieve tube
companion cell
sieve plate
plasmodesmata
living cells
Phloem: food-conducting cells
 sieve tube elements & companion cells
Fig. 38.14a
Fig. 38.14b
Phloem
Aaaah…
Structure–Function
again!
Living cells at functional maturity •
cell membrane, cytoplasm –
control of diffusion •
lose their nucleus, ribosomes & vacuole –
more room for specialized transport of •
liquid food (sucrose)
Cells •
sieve tubes –
sieve plates — end walls — have pores to facilitate flow of •
fluid between cells
companion cells –
nucleated cells connected to the sieve-tube •
help sieve tubes •
Fig. 38.15
Cross section of root
Vascular bundle (Stele) = contains xylem and phloem
Cortex
Epidermis
Root hairs
Absorb water and minerals –
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•
•
Vascular tissue in roots: dicot
phloem
xylem
Cross-section of a root
Vascular tissue in roots: monocot
xylem
phloem
Root Cross Section
Vascular tissue in stems
dicot
trees & shrubs
collect annual rings
monocot
grasses & lilies
Cross-section: young dicot stem with ring of vascular bundles
Fig. 38.25a
Fig. 38.25b
Monocot stem section showing scattered
vascular bundles and enlargement of single
vascular bundle (“monkey face”).
Woody dicots
Discrete vascular bundles replaced by •
continuous rings of xylem
Each ring is xylem produced during one •
growing season
Vascular cambium •
Fig. 38.7a
Fig. 38.7b
Cross-section:
woody stem
showing 3 years
of secondary
growth. Note pith
at center. Dark
(reddish) ring is
the bark
containing a layer
of living phloem
and outer dead
cork.
Stems: Secondary growth
•Vascular tissue, (xylem) makes up the bulk of the stem
•Form tree rings
Lilac leaf cross section
Fig. 38.34
Fig. 38.8
Fig. 38.33