1.1 Classify the specimens according to their types of root systems:
corn (Zea mays L.) – fibrous
mung bean – tap
carrot (Daucus carota L.) – tap
radish (Raphanus sativus L.) – tap
sweet potato – tap
ginger (Zingiber officinale Roscoe) – fibrous
ginger lily (Hedychium coronarium Koen.) – fibrous
taro (Colocasia esculenta (L.) Schott.) or any Araceae – fibrous
onion or any Liliceae or Amaryllidaceae – fibrous
roots or leaves of life plant (Kalanchoe sp.) – fibrous
cuttings of begonia (Begonia sp.) – fibrous
bowstring hemp – fibrous
3. Examine the root system of water hyacinth and note the sequential development of tissues from the tip to the base.
3.1 Where are the youngest roots located? the oldest?
Youngest located at the tip of the root. Oldest located that the base of the root.
3.2 Identify the structure covering the root tip.
4. Examine under the microscope a cross-section of a young monocot root of spiderwort, Commelina benghalensis L. or corn and any dicot root. Locate and note the following primary tissues: epidermis, cortex, stele and pith.
4.1 Do you see the sub-epidermal cells (hypodermis or exodermis) in your specimen? If so, how many layers?
4.2 In which tissue are the intercellular spaces evident?
4.3 What features make the endodermis morphologically distinct?
4.4 Determing the number of layers and cell types in the pericycle
4.5 How many protoxylem poles do you see in your specimen?
4.6 Is the pattern of xylem differentiation endarch or exarch?
4.7 Is there a pith in the root core of your specimen?
4.8 What tissue gives rise to the lateral root?
4.10 Differentiate a root hair from a branch root
Root hairs are unicellular, epidermal outgrowth which are only temporary. Branch roots are multicellular, endogenous, long lasting and develop from mature roots.
4.11 What region occupies the largest in the root?
Region of elongation
4.12 Tabulate the anatomical differences between monocot and dicot root.
Dicot – tetrarch, shows second growth, phloem between arms of xylem
Monocot – polyarch, vascular bundles arranged in a ring
5. Examine the cross section of a woody dicot root
5.1 Enumerate the cell components of the bark and wood
5.2 Do you find root hairs? Why?
No. Epidermis, where root hair is found, is sloughed off during secondary growth.
5.3 Which tissue usually functions in food storage in an old root? Young root?
6. Examine the intact (entire) and cross-section of the root or radish, turnip, Pachyrrhizus erosus (L.) Urb. and sweet potato.
6.1 What tissues of these roots are edible?
Secondary tissue produced by cambia and upper part of root
7. Examine other specialized roots and tabulate their functions.
Plant Specimen – Specialized Part – Modification – Function(s)
Radish – Tap – Enlarged, fleshy – Food storage
Carrot – Tap – Enlarged, fleshy – Food storage
Sweet Potato – Tap – Enlarged, fleshy – Food storage
Turnip – Tap – Enlarged, fleshy – Food storage
Mangrove – Fibrous – Aerial root – Support
Pandan – Fibrous – Prop root – Support
8. Examine the cross section of the root of an aerial orchid and study the tissues
8.1 How does its morphology compare with the corn root?
Orchid has velamen which protects the aerial roots.
Some answers differ for each class/group. You need to do the experiment.
For 4.1, 4.4 & 4.5, answers depend on your specimen/slide.