1. BIO20B
Development & Physiology
Prof. Justin Cummings
Plant Physiologist /Restoration
ecologist

2. Lab #1 Plant morphology
•Print out handouts from eCommons
•All assignments are to be turned in at 2:00 on
Friday

3. Plant of the week #1
Coast redwood, Sequoia sempervirens
World’s tallest living species
2000+ years old
Stump-sprouting
Thick bark
UCSC’s redwood

4. • Kingdom: Plantae
-Includes glaucophytes, red algae, and green
plants
-All descended from an ancestral organism
with primary chloroplast

5. •Green Algae- ancestral organism
to all land plants

6. Adaptations allowing for the colonization of land
by plants
1.Cuticle: waxy covering of leaves
2.Stomata: Openings in leaves and stems that allow for gas exchange
3.Gametangia: multicellular organs that enclose plant gametes and prevent them from
desiccating
4.Embryos: young plants contained within a protected structure
5.Pigments: allow for protection against harmful uv radiation
6.Fungal mutualism: promotes nutrien and water uptake from soil

7. Gymnosperms vs. Angiosperms
Gymnosperms- Seed plants that
don’t produce flowers
Angiosperms- Flowering plants

8. Angiosperms: Monocots vs. Eudicots
Arrangement of
Cotyledons Veins in leaves flower petals vascular bundles
in stem
Monocot 1 parallel Usually in
multiples of 3 scattered
Eudicot 2 netlike Usually in
multiples of 4 or 5 in a ring

9. Autotrophs: Obtain carbon through atmospheric
carbon fixation and photosynthesis
What do plants need?
•Light
•CO_2
•Water
•Minerals

10. Basic Plant Structure
• Shoot system
• Stem and Leaves
-Photosynthesis and Water/Nutrient Transport
•Root System
•Roots
-Absorb water, nutrients, and stores products from photosynthesis

11. Fig 5.7
•
Plants Cell
•90% of cell volume
•Primarily serves as a storage structure
•Water filled sacks containing minerals, enzymes, amino acids, and
sugars from photosynthesis

12. •2 cells walls
•Primary and secondary cells walls
•Primary cell wall
Mades up of hemicellulose and pectins
•Secondary cell wall
•Internal to primary cell wall
•Increases structural support
•Embedded with lignin

13. Meristematic cells give rise to more specialized cells
• Undifferentiated cells
• Cell division -> one meristem cell; one differentiated specialized cell
3 Types of mature cells
3 Types of tissue
Parenchyma
Dermal
Schlerenchyma
Ground
Collenchyma
Vascular

14. 1. 3 types of cells
PARENCHYMA
•Most common cell types
•Most of a leaf
•Metabolically active
•Totipotent
( e.g. wounding, cuttings)
•Primary cell wall; middle lamella (region between cells that binds them
together) (no secondary cell wall)
•Large vacuoles
Involved in:
•Photosynthesis
•Storage cells in roots
•Most of a fruit

15. 2. 3 Types of mature cells
From the Greek: “Glue”
COLLENCHYMA
• Flexibility and support
• Thickened primary cell walls; no secondary wall
• Occur in bundles
• Tend to be long, pliable ------- Why is celery stringy
• (Alive when mature)
• Rich in pectins ------Jelly

16. 2. 3 types of mature cells
COLLENCHYMA
• Provide support to petiole, non-woody stems, and growing organs

17. 3. 3 types of mature cells
From the Greek: “Hard”
SCLERENCHYMA
•Function: Structural Support
•Thick 2º cell walls
•Lignified
•Dead when mature
(in non- growing parts)
•Protection of seed & fruits
•Different types:
•Sclereids----------- Why are pears gritty
•Fibers ----------------- Most of what we wear!

18. Fibers
Rigid sipport to wood
Sclereids
Densly packed cells; e.g. Nut Shell

19. 1. Dermal Tissue
From the Greek “Over skin”
EPIDERMIS
• One-cell thick
• Cuticle (wax on surface
• Specialized cells
• Tichomes
• Root hairs
Periderm- Dermal tissue of stems and roots of woody plants

20. 2.
Ground Tissue
• Between dermal and vascular tissue
• Metabolically active
• Photosynthesis, storage
(parenchyma)
• Support
(schlerenchyma, collenchyma)

21. 3. From the latin
“small vessel”
VASCULAR TISSUE
• Continuum of phloem and xylem
• Transport
• Phloem: sugars
• Xylem : water
• Support (xylem)

22. Two specialized cels in vascular tissue: Xylem
and Phloem
4. Tracheary elements (=schlernchyma)
• Dead when mature
• Thick cell walls
• Interconnect via pits in walls
• Connect end to end
• Conduct water
• Tracheids (gymnosperms & vessel elements
(angiosperms)

23. Two specialized cells types in vascular tissue:
Xylem and Phloem
5. Sieve tube cells = parenchyma
• Live when mature
• Missing nuclei , vacuoles....
• Need companion cells
• Connect end to end
(sieve plates)

24. * This will be on the test
Organs in the roots Organs in the shoots
roots stem leaves
3 Types of Tissue
Dermal Vascular Ground
3 Types of cells
Parenchyma Collenchyma Schlerenchyma

25. Look at root and shoot in book

26. How do plants grow?
• Plants show indeterminate growth (keep growing.
• Totpotent cells (1 cell-> whole organism).
Meristems
• Cells unspecialized
• Divide ->additional cells
Apical meristem Lateral meristem
1º growth 2) growth (thickening
e,g. roots * shoot tips e.g. tree trcuk

27. MERISTEMS cont.
What if meristem is damaged?
• Other cells become meristematic
After the meristem
• All subsequent growth = elongation

28. MERISTEMS cont.
How does a tree grow?
Then, 2º growth from lateral meristems <Vascular cambium
Cork cambium
1º growth from apical meristem

29. What’s a growth ring?
In Winter/spring, lots of rain,
• Xylem cells bigger,
• with thin walls
= light
In Summer/fall, dry
• Xylem cells smaller
• with thick walls
= dark

30. How do little bunnies
kill big trees
“Girdling”
Because the
cambium (the
meristem) is
close to the
surface