1. Monocot Roots large vascular cylinder in center
ring pattern of xylem (large openings) and phloem tissue surrounded by endodermis
vascular cylinder surrounded by fairly thick cortex
fibrous root system

2. Dicot Roots small vascular cylinder in center;
large openings are xylem tissue surrounded by smaller phloem cells in a ‘star’-shaped pattern
very thick cortex
tap root system

3. Stems
support leaves
transport materials between roots and leaves (e.g. water, sugar)
storage of food (e.g. sugars)
may be photosynthetic
Woody stems: found in trees and shrubs, don’t die back in winter, annual rings used to determine age
Herbaceous stems: green in colour, contain chlorophyll, undergo photosynthesis, die back in winter

4. Monocot Stems
vascular bundles scattered in fundamental (ground) tissue

5. Dicot Stems
vascular bundles in ring pattern in fundamental tissue

6. HERBACEOUS STEMS
Vascular Bundles
collection of xylem and phloem
xylem is closer to the inside
and phloem the outside
phloem
xylem

7. Vascular Cambium
between the xylem and the phloem
this is where new xylem and phloem are made
vascular cambian

8. Woody stem
Heartwood
dead cells fill with materials that harden
Sapwood
active xylem that transports water & minerals
sapwood
heartwood

9. new layers of xylem & phloem cells allow stem to grow in width
Vascular Cambium
new layers of xylem & phloem cells allow stem to grow in width
Cork
dead phloem cells containing chemicals
Bark
outer protective layer, also dead phloem
vascular cambian
cork
bark

10. Annual rings
more xylem forms in wet months (light band) than in dry months (dark band)
Dry months
Wet months

11. bark
annual rings
cambium
pith
rays
heartwood
sapwood

12. Both herbaceous and woody stem types are found in monocots and dicots
However there is no secondary growth (stem diameter increases) for woody monocot stems and thus no “tree rings” to use to determine their age.
Palm tree cross-section showing no annual rings

13. Modified Stems
Tuber: modified for food storage, grow underground (e.g. potato)
Bulb: underground stem with layers of modified leaves (e.g. onion)
Corm: enlarged, underground stem, with scaly leaves (e.g. gladioli)
Rhizome: thick, fleshy underground stems (e.g. irises)
tuber
bulb
corm
rhizome

14. Leaves main function is photosynthesis
(carbon dioxide + water --> glucose + oxygen)
green colour due to chlorophyll pigment which absorbs energy and reflects green
a. Leaves tend to be broad and flat to increase the surface area exposed to sunlight. b. Photosynthesis occurs primarily within the mesophyll cells in the interior of the leaf. The vascular bundles carry water to the leaves and carry the product of photosynthesis, sugar, to other parts of the plant. It is the pores called stomata, mostly on the underside of leaves, that allow for the passage of gases in and out of the leaf. c. Guard cells of the stomata control the opening and closing of the stomata. When sunlight shines on the leaf during the day, the guard cells engorge with water that makes them bow apart, thus opening the stomata.When sunlight is reduced, water flows out of the guard cells, causing the stomata to close.

15. Cuticle:
waxy layer that prevents water loss
Epidermis:
Outer layer of cells that protects the leaf

16. Palisade Layer
Main site of photosynthesis as cells have many chloroplasts
Spongy Layer
Some photosynthesis, but lots of air spaces [for CO2]

17. Vein
Xylem & phloem to bring water & remove sugars
Guard Cells
Stoma(ta)
Small openings that allow air in and out of leaf
Cells that swell when filled with water to open stoma

18. Monocot Leaves veins (vascular bundles) are spaced evenly along leaf
leaves tend to be long & narrow
stomata allow exchange of gases

19. Dicot Leaves veins are large, spaced randomly through leaf
leaves are broad, have many parts
stomata found mostly along bottom of leaves

20. Leaf Adaptations
spines (e.g. cacti and pine needles) have thick waxy cuticle to prevent water loss
thick leaves (e.g. jade plant) are used for water storage
aquatic plants (e.g. water lily) must have stomata on upper surface of leaf only for gas exchange

21. Drawing some plant parts
Draw a cross section of each the following:
Monocot root and dicot root (using the ‘wedge’)
Monocot stem and dicot stem (using the ‘wedge’)
Monocot leaf and dicot leaf (drawing everything)

22. Name of Specimen (stain used if known)
Magnification Number
“Wedge” is large enough to show detail of pattern
“Wedge” includes centre of field of view
High detail inside wedge including stippling
Low detail outside of wedge to show pattern
Wedge is in centre or on right side of field of view
All plants have vascular bundles.
(VERY IMPORTANT TO SHOW!!!)
THE “WEDGE” METHOD:Used when specimens take up the entire field of view or to show repeating patterns in a specimen.