1. Plant Structure, Growth, and Development (Ch. 35)

2. What are Angiosperms?

3. Angiosperm Body 2 Taxonomic classes monocots eudicots Monocots
One cotyledon
Parallel veins
Floral parts in 3’s
Fibrous Roots
Eudicots
Two cotyledons -
Netlike veins
-Floral parts in 4’s and 5’s
Tap root

4. Angiosperm Body
Need to be able to inhabit soil and air at the same time
roots and shoots
Plant morphology
study of the external structure
arrangement of flower parts, etc.
Plant anatomy
study of the internal structure
arrangement of cells, tissues in a leaf, etc.
Tissue – groups of cells, consisting of one or more types, that perform a specialized function
Organ – consists of several types of tissues that together carry out specific functions

5. Angiosperm Body Two basic systems root system
aerial shoot system (stems, leaves, flowers)
Vascular Tissues
transport materials
xylem transports water and dissolved minerals
phloem transports food

6. Root System
Anchoring, absorbing water and minerals, storing carbohydrates
Taproot system
one large, vertical root
mostly eudicots
firm anchorage; one large vertical root
stores lots of reserve food
gives rise to lateral roots

7. Root System Fibrous root system mat of threadlike roots
mostly monocots
extensive exposure to soil, water, minerals
concentrated in topsoil; prevents erosion

8. Root System Adventitious roots
plant organ that grows in an unusual location
arising above ground or from stems/leaves
Root hairs
thin, tubular extension of a root epidermal cells
increase SA near root tip

9. Root System Mycorrhizae
mutualistic relationship between fungi and roots
Root nodules
contain symbiotic bacteria to convert atmospheric nitrogen to compounds usable by the plant

10. Modified Roots (a) Prop roots (b) Storage roots
(c) “Strangling” aerial roots
(d) Buttress roots
(e) Pneumatophores

11. Shoot System Vegetative shoots Stems and leaves Floral shoots Flowers
Alternating system of nodes and internodes
Raises or separates leaves
Raise reproductive structures

12. Shoot System - Stems Nodes where leaves attach to stems Internodes
segment of stem between nodes
Axillary bud
embryonic side shoot
has potential to form a branch shoot
usually dormant in young plants
pruning

13. Shoot System - Stems Terminal (apical) bud
bud on shoot tip; composed of developing leaves and a compact series of nodes and internodes
where most of the growth of a young plant occurs
May inhibit growth of axillary buds
apical dominance

14. BELL RINGER

15. Modified Stems Stolons
Runners allow plant to colonize a large area & reproduce asexually
Rhizomes
Horizontal stem that grows below ground
Tubers
Swollen ends of rhizomes; store food
Bulbs
Vertical, underground shoots

16. Modified Stems Rhizomes. The edible base
of this ginger plant is an example
of a rhizome, a horizontal stem
that grows just below the surface
or emerges and grows along the
surface.
(d)
Tubers. Tubers, such as these
red potatoes, are enlarged
ends of rhizomes specialized
for storing food. The “eyes”
arranged in a spiral pattern
around a potato are clusters
of axillary buds that mark
the nodes.
(c)
Bulbs. Bulbs are vertical,
underground shoots consisting
mostly of the enlarged bases
of leaves that store food. You
can see the many layers of
modified leaves attached
to the short stem by slicing an
onion bulb lengthwise.
(b)
Stolons. Shown here on a
strawberry plant, stolons are horizontal stems that grow
along the surface. These “runners”
enable a plant to reproduce
asexually, as plantlets form at
nodes along each runner.
(a)
Storage leaves
Stem
Root
Node
Rhizome

17. Shoot System - Leaves Main photosynthetic organ Blade
Petiole
(a) Simple leaf. A simple leaf is a single, undivided blade. Some simple leaves are deeply lobed, as in an oak leaf.
(b) Compound leaf. In a compound leaf, the blade consists of multiple leaflets. Notice that a leaflet has no axillary bud at its base.
(c) Doubly compound leaf. In a doubly compound leaf, each leaflet is divided into smaller leaflets.
Axillary bud
Leaflet
Shoot System - Leaves
Main photosynthetic organ
Blade
Joined to node by a petiole
Venation (vascular tissue)
parallel
netted
Classification
shape
spatial arrangement
venation

18. Modified Leaves Tendrils on vines Spines of cacti Storage Reproductive
Bracts

19. Dermal, Vascular, and Ground Tissues
Tissue system
A functional unit connecting all of the plant’s organs
Dermal tissue system
Outer protective covering
Epidermis in nonwoody plants
Cuticle
Periderm in woody plants

20. Dermal, Vascular, and Ground Tissues
Vascular tissue system
Long distance transport b/w roots and stems
Xylem and phloem
Collectively called the stele
Ground tissue system
If internal to the vascular tissue  pith
If external to the vascular tissue  cortex

21. Plant Cells Protoplast
contents of a plant cell not including the cell wall
Lignin
Structural component of cell walls
All start out similar to parenchyma cells; become more specialized
Can generate an entire plant from one parenchyma cell

22. Plant Cells Parenchyma cells “typical” plant cell
chloroplasts for photosynthesis
large central vacuole
store starch
comprise fleshy tissue of fruits
Collenchyma cells
unevenly thick primary walls
support for young plants without restraining growth
living and flexible throughout life

23. Plant Cells Sclerenchyma cells
rigid, thick secondary walls with lignin
function only in support
may be dead at maturity but produce secondary walls before protoplast dies
Sclereids
Very thick cell lignified cell walls; nutshells & seed coats
Fibers
Long, slender and tapered

24. Plant Cells Water-conducting cells of xylem
dead at functional maturity
allow water to flow from cell to cell
tracheids
In nearly all vascular plants
Water moves through pits
vessel elements
Angiosperms and some gymnosperms
Water moves through perforation plates

25. Plant Cells Food-conducting cells of phloem
alive at functional maturity
sieve-tube cells make the sieve tube elements/members that transport sucrose and other organic nutrients
sieve plate
Pores that allow flow from cell to cell
companion cells
Ribosomes and nucleus serve the sieve tube cell too

26. Figure 35.12 Locations of major meristems: an overview of plant growth

27. Meristems generate cells for primary and secondary growth
Begins with germination and occurs throughout life of plant
Indeterminate growth
Meristems
perpetually undifferentiated tissues
Apical meristems
Responsible for primary growth (growth in length)
Lateral meristems
Responsible for secondary growth (growth in thickness)

28. Meristems generate cells for primary and secondary growth
Two types of lateral meristems
Vascular cambium
Add layers of vascular tissue called secondary xylem (wood) and secondary phloem
Cork cambium
Replaces the epidermis with thicker, tougher periderm

29. Plant Growth Finite life span genetically & environmentally determined
annuals, biennials, and perennials
Annuals
Complete their life cycle in a year
Cereal grains, legumes, wildflowers
Perennials
Live many years
Trees, shrubs, some grasses
Biennials
Life span –generally 2 years
Live through an intervening cold period between vegetative growth and flowering
Beets, carrots

30. Figure 35.14 Primary growth of a root

31. Primary Growth Lengthens Roots and Shoots
Primary growth of roots
pushes roots through soil; root cap covers apical meristem
Zone of cell division
apical and primary meristems
Zone of cell elongation
elongate in size
Zone of maturation
specialize in function

32. Primary Growth Lengthens Roots and Shoots
Epidermis
Ground tissue
Vascular tissue
Stele
Endodermis
Pericycle

33. Primary Growth Lengthens Roots and Shoots
Primary growth of shoots
Apical meristems give rise to primary meristems
Leaf primordia give rise to leaves
Shoot elongation is due to lengthening of internode cells below the shoot tip
Branching occurs due to activation of axillary buds

34. Tissue Organization of Stems
Epidermis
Covers stems
Vascular tissue in bundles
Axillary buds meristems develop lateral shoots
Parenchyma, collenchyma, and scelerenchyma cells are present

35. Tissue Organization of Leaves
Epidermis
tightly locked cells
protect from damage & pathogens
waxy cuticle
Stomata
pores on underside of leaf
site of gas exchange
Guard cells
control stomata opening for gas exchange
Flaccid  stomata are closed due to lack of water

36. Tissue Organization of Leaves
Mesophyll
Ground tissue of leaf between epidermal layers
palisade parenchyma
upper half of leaf
spongy parenchyma
air spaces to allow O2 and CO2 to circulate
lower half of leaf

38. Tissue Organization of Leaves

39. Vascular Cambium and Secondary Vascular Tissue
Secondary growth of stems
Stems and roots of woody plants
vascular cambium
transport and storage of starch
Adds secondary xylem (wood) and secondary phloem
cork cambium
protective layers
Bark (refers to all tissues external to vascular cambium)
phloem, phelloderm, cork cambium, cork
Secondary growth of roots

40. An overview of primary and secondary growth

41. Cork Cambium and Production of Periderm
Phelloderm
Thin layer of parenchyma cells that forms to the interior of the cork cambium
Accumulation of cork cells
Deposit suberin in walls then die
Protects from water loss, physical damage, pathogens
Lenticels
Small, raised areas in the periderm
Help cells to exchange gases

42. Growth, Morphogenesis, and Cell Differentiation Produce the Plant Body
Development
Specific series of changes by which cells form tissues, organs, and organisms
Growth
Irreversible change in size
Cell division and expansion
Morphogenesis
Process that gives a tissue, organ, or organism its shape and determines the positions of cell types
Pattern formation
Differentiation
Process by which cells with the same genes become different from one another
Control of gene expression