From Cell to Organ-10 
201 Syllabus
From Cell to Organ-10
201 Syllabus
Tissue Organization and Organs
The most
simple pattern of tissue organization is seen in Roots.
Imagine a stack of ice cream cones. Fill the first cone with raspberry
ice cream. This is the Xylem. Coat the inside of a second cone
with a layer of blueberry ice cream. The ice cream represents the Phloem.
Place this over the first cone. Coat another cone with mint ice cream and
place it over the other two cones. The mint ice
cream is ground tissue. We should have a stack of three
cones. The outermost cone shell is the Epidermis.
Some Stems and Leaves have the same kind of organizational pattern! This is especially true for the most ancestral land plants.
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 The Root and some Stems have concentric circles of Epidermal Ground & Vascular Tissues |
 Some Leaves have only one Vascular Bundle. These are called Microphylls. |
 Stem X-section |
 Microphyll (Small Leaf) |
 Dicots like Ohi'a Lehua have a large central Vascular Bundle called a Midrib, plus smaller Lateral Bundles. |
 Leaves of Monocots like Sugarcane have many Vascular Bundles of similar dimensions. |
 Dicot Leaf X-section (Megaphyll) |
 Monocot Leaf X-section (Megaphyll) |
| These leaves are called Megaphylls because they have more than one vein, among other traits. | |
 Monocot Stems have many Vascular Bundles arranged in a complex pattern within the Ground Tissues. |
 Dicot Stems have one ring of Vascular Bundles located in the periphery of the Ground Tissues. |
 Monocot Stem x-section |
 Dicot Stem X-section |
