Presentation is loading. Please wait.

Presentation is loading. Please wait.

The leaf is the main photosynthetic organ of most vascular plants Leaves - Overview Shoot system Leaf Blade Petiole Leaves generally have a flattened blade.

Similar presentations


Presentation on theme: "The leaf is the main photosynthetic organ of most vascular plants Leaves - Overview Shoot system Leaf Blade Petiole Leaves generally have a flattened blade."— Presentation transcript:

1 The leaf is the main photosynthetic organ of most vascular plants Leaves - Overview Shoot system Leaf Blade Petiole Leaves generally have a flattened blade and a stalk called the petiole, which joins the leaf to a node of the stem

2 Most Dicots have branch-like veins and palmate leaf shape Monocots have parallel leaf veins and longer, slender blades Leaves - Comparisons Monocots and Dicots differ in the arrangement of veins, the vascular tissue of leaves

3 1. Stoma (stomata) – small pores that act as a doorway for gases involved in photosynthesis (found mainly on the underside of leaves). 2. Guard Cells – Cells that regulate the opening of the stomata. 3. Lower and upper epidermis – outer layer of a plant that serves for protection, like skin.

4 4. Palisade layer – layer where majority of chloroplasts are found ( site of photosynthesis ). 5. Spongy layer – cells surrounded by air spaces; allow water, CO 2 and O 2 to diffuse during photosynthesis. 6. Waxy layer/cuticle – protects leaf from water loss and from feeding insects.

5 Leaves – Structure and Development Most dicots have 2 types of mesophyll –Palisade mesophyll high photosynthesis –Spongy mesophyll air spaces for gas & water exchange Monocot leaves have 1 type of mesophyll

6

7 Leaves – Structure and Development Leaves are several layers thick – each with different cell types

8 Epidermis Leaves Leaf epidermis contains stomata - allow CO 2 exchange Stomata flanked by two guard cells, control open vs. closed The ground tissue in a leaf, called mesophyll, fills the middle Key to labels Dermal Ground Vascular Cuticle Sclerenchyma fibers Stoma Bundle- sheath cell Xylem Phloem (a) Cutaway drawing of leaf tissues Guard cells Vein Cuticle Lower epidermis Spongy mesophyll Palisade mesophyll Upper epidermis Guard cells Stomatal pore Surface view of a spiderwort (Tradescantia) leaf (LM) Epidermal cell (b) 50 µm 100 µm VeinAir spacesGuard cells Cross section of a lilac (Syringa)) leaf (LM) (c)

9  Xylem – cells that carry water and dissolved minerals from the roots to the leaves.  Phloem – cells that carry food (sugar) that is made in the leaves to all parts of the plant. Use: Collectively the vascular tissue, xylem and phloem create a vein or vascular bundle to transport material in plants.

10  Open – with light and when guard cells are filled with water.  Closed – without light and when guard cells are lacking water (dehydrated).  Why is it important to have stomata open? Closed vs. Open

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25 Question time????????

26


Download ppt "The leaf is the main photosynthetic organ of most vascular plants Leaves - Overview Shoot system Leaf Blade Petiole Leaves generally have a flattened blade."

Similar presentations


Ads by Google