Plant Organization: Leaf development

1. Plant Organization: Leaf development

2. Organization Organization in plants is dependent upon programmed, controlled cell division, followed by growth, further cell division and ultimately, differentiation. Programmed and controlled cell division occurs within the domain of the vegetative apex. Leaves also follow a programmed development process

3. the apex All the tissues within the apex differentiate rapidly. By about 150 µm, cells within the apical region are starting to differentiate. In the pine apex (above), you can see developing leaflets. The Coleus apex to the right, shows rapidly developing leaflets beneath the apical dome.

4. internal organization adaxial epidermis palisade mesophyll vascular bundles spongy mesophyll stomata

5. leaf development these form the epidermis and associated structures marginal two types of initials submarginal these form mesophyll as well as the procambial and cambial tissue

6. how organized? epidermal, mesophyll and vascular tissues are organized and develop in specific ways. What is the control mechanism?

7. structural & functional tissue dermal non- vascular vascular dermal

8. two meristems sub marginal marginal

9. deriving procambium marginal sub marginal procambium

10. Esau’s developmental outline upper epidermis palisade parenchyma bundle sheath Vascular bundles procambium MI SI bundle sheath middle spongy parenchyma lower spongy parenchyma lower epidermis see notes below

11. no middle spongy layer? upper epidermis palisade parenchyma bundle sheath procambium vascular bundles MI SI bundle sheath lower spongy parenchyma lower epidermis

12. add a mestome sheath upper epidermis palisade parenchyma bundle sheath mestome sheath MI SI procambium vascular bundles mestome sheath bundle sheath lower spongy parenchyma Notes lower epidermis