Morphology of Stems
Session 6: Morphology of Stems
Total Session Time: 120 minutes
Prerequisites
Learning Tasks
By the end of this session students are expected to be able to:
Resources Needed:
SESSION OVERVIEW
|Step |Time |Activity/ |Content |
| | |Method | |
|1 |05 minutes |Presentation |Introduction, Learning Tasks |
|2 |20 minutes |Presentation |Introduction to Stems and External|
| | |Brainstorming |Features |
|3 |35 minutes |Presentation |Internal Structures of Dicot Stems|
|4 |30 minutes |Presentation |Internal Structures of Monocot |
| | | |Stems |
|5 |20 minutes |Presentation |Differences between Monocot and |
| | |Small group |Dicot Stems |
| | |discussion | |
|6 |05 minutes |Presentation |Key Points |
|7 |05 minutes |Presentation |Evaluation |
SESSION CONTENTS
STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)
READ or ASK students to read the learning objectives and clarify
ASK students if they have any questions before continuing.
STEP 2: Introduction to Stems and External Features (20 minutes)
have underground stems
o Stems support the leaves and other structures e.g. flowers,
fruits
o Stems are used for vegetative reproductive i.e. cuttings
o Stems position leaves to receive maximum sunlight
o Stems determine size and shape of the plant
o Facilitates movement of water, minerals, and manufactured
food in the plant
o Some stems carry out photosynthesis
o Stores foods
|Activity: Brainstorming (5 minutes) |
| |
|Ask students to brainstorm on the following question: |
| |
|What are the external structures of the stem? |
| |
|ALLOW few students to respond? |
| |
|WRITE their responses on the flip chart/ board |
| |
|CLARIFY and SUMMARISE by using the content below |
o Internodes: distances separating one node from
another
o Nodes: Points at which leaves are attached
o Lenticels: Breathing pores
o Buds: Growth of shoot
o Terminal or apical but, at tip of plan
o Axillary bud in nodes on stem
o Bud scale scars: Indicate where terminal bud has been located previous
year
o Leaf scars:
o Show where leaf was attached
o Usually consist of three tissues, Dermal tissue, Ground
tissue and Vascular tissue
o The dermal tissue
protect & control gas exchange
o The Ground tissue
sometimes functions in photosynthesis
o The Vascular tissue
STEP 3: Internal Structures of the Dicot Stem (35 minutes)
and Stele.
o Epidermis
substance
o Cortex
collenchyma cells
intercellular spaces
[pic]
o The Stele
o Layers of cells between endodermis and vascular bundles
o Consist of xylem, phloem and cambium
o Xylem and phloem in stem occur together to form the vascular
bundles
o These vascular bundles are wedge shaped
o The vascular bundle is conjoint, collateral, open and endarch
o Phloem
parenchyma
other parts of the plant body
o Cambium
cells
o Xylem
tracheids
parts of the plant body
o It is the large central portion of the stem
o It is composed of parenchyma cells with intercellular spaces
o The pith extends between the vascular bundles and form primary
medullary rays
o These extensions of the pith between the vascular bundles are
called
o It stores food
STEP 4: Internal Structures of the Monocot Stem (30 minutes)
o Epidermis,
o Hypodermis,
o Ground tissue and
o Vascular bundles
parenchymatous cells and covered with a thick cuticle in some
plants
epidermis
closed
STEP 5: Differences between Dicot and Monocot Stems (20 minutes)
|Activity: Small Group Discussion (10 minutes) |
| |
|DIVIDE students into small manageable groups |
| |
|ASK students to discuss on the following question |
| |
|What are the differences between monocot and dicot stems? |
| |
|ALLOW students to discuss for 10 minutes |
| |
|ALLOW few groups to present and the rest to add points not |
|mentioned |
| |
|CLARIFY and SUMMARIZE by using the contents below |
[pic]
STEP 6: Key Points (10 minutes)
usually above the ground, and in some plants below the ground. The stem
supports the leaves
lenticels, buds, leaf scars and bud scales
various function of support, storage, transport and photosynthetic in
some plants
STEP 7: Evaluation (5 minutes)
References
Trease, G. E., Evans, W. C., & Evans, D. (2009). Trease and Evans
pharmacognosy. London: Saunders.
Joanne Barnes et al (2002), Herbal medicines 3rd Edition: Pharmaceutical
Press
Wallis, T. E. (2005). Textbook of pharmacognosy. New Delhi: CBS.
Robbers, J. E., Speedie, M. K., Tyler, V. E., & Tyler, V. E. (1996).
Pharmacognosy and pharmacobiotechnology. Baltimore: Williams &
Wilkins.
Heinrich, M., Kinghorn, A. D., Maizels, D., Gibbons, S., & Phillipson, J.
Churchill Livingstone/Elsevier.
Unataka kutumiwa notes hizi kupitia WhatsApp?Kwa notes zilizopangiliwa vizuri kwa kusoma offline au PDF, bonyeza kitufe hapa chini. Ujumbe wenye Level, Semester, Module na Topic utaandaliwa moja kwa moja.TUMIWA NOTES WHATSAPP
