Plant Anatomy

Spikelet

Inflorescence

Internode

Culm (stem)

Node (joint)

Rhizome

StolonLeaf

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 walls–support

•Sclerenchyma –very thick, “woody” secondary walls–support–rigid cells that can’t elongate–dead at functional maturity

If I’d onlyhad triplets!

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 stalksare 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

tracheids

vessel elements Vascular tissue

Aaaah…Structure–Functionagain!

vessel element

dead cells

Xylem move water & minerals up from roots dead cells at functional maturity

only cell walls remain need empty pipes to efficiently move H2O transpirational pull

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

living cells

plasmodesmata sieve plate

Phloem: food-conducting cells sieve tube elements & companion cells

Fig. 38.14a

Fig. 38.14b

Phloem•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

Aaaah…Structure–Functionagain!

Fig. 38.15

Cross section of root•Vascular bundle (Stele) = contains xylem and phloem•Cortex•Epidermis•Root hairs

–Absorb water and minerals

Vascular tissue in roots: dicot

xylemphloem

Cross-section of a root

xylem

phloem

Vascular tissue in roots: monocot

Root Cross Section

Vascular tissue in stems

dicottrees & shrubs

monocotgrasses & lilies

collect annual rings

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