Under synthetic tissue are grouped all tissues and cells which form substances or compounds other than protoplasm. Such compounds are stored either in special cavities or in the cells of the plant, as the glandular hairs; internal secreting cavities of barks, stems, leaves, fruits, seeds, and flowers; photosynthetic cells or cells with chlorophyll, and the parenchymatic cells which form starch, sugar, fats, alkaloids, etc.
The most important non-glandular synthetic tissue is the photosynthetic tissue, which is composed of the chlorophyll-bearing cells of the plant. These are the so-called green cells of leaves, of stems of herbs, of young woody stems, and in the older woody stems of plants like wild cherry, birch, etc.
<Callout type="important" title="Key Role">Leaves collectively constitute the greatest synthetic manufacturing plant in the world because the green cells of the leaf produce most of the food of men and animals.</Callout>
During the day a large quantity of starch is formed. At night through the action of a ferment the excess of starch remaining in the leaf is converted into sugar (C6H12O6) — C6H10O5 + H2O = C6H12O6. In this form it is distributed to the living cells of the plant.
The glandular tissue of the plant is divided into two groups, according to where it occurs. These groups are, first, external glandular tissue, and secondly, internal glandular tissue. The most important external glandular tissue is composed of the glandular hairs. These are divided into two groups: first, unicellular; and secondly, multicellular glandular hairs.
Multicellular uniseriate stalked glandular hairs occur on the leaves of tobacco (Plate 61, Fig. 4), belladonna (Plate 61, Fig. i). In each of these hairs there are eight secretion cells.
Key Takeaways
- Photosynthetic tissue is crucial for producing food through the combination of carbon dioxide and water into starch.
- Glandular tissues produce essential oils, alkaloids, and other compounds used in medicine.
- Understanding plant structures can aid in identifying medicinal plants.
Practical Tips
- Use Lugol's solution to test for starch presence in leaves.
- Identify glandular hairs by their structure and location on the plant.
- Recognize different types of glandular hairs (unicellular, multicellular) based on their characteristics.
Warnings & Risks
- Be cautious when handling plants with glandular hairs as they may contain irritants or toxins.
- Incorrect identification can lead to ingestion of harmful substances.
Modern Application
While the chapter focuses on historical plant anatomy and chemistry, understanding these principles is still crucial for identifying medicinal plants in survival situations. Modern techniques have advanced our ability to analyze compounds but knowing how to identify them through physical characteristics remains vital.
Frequently Asked Questions
Q: How can I test for starch presence in leaves?
To test for the presence of starch in leaves, place the leaf in hot alcohol to remove chlorophyll and then add Lugol's solution. If starch is present, the contents of the cells will become bluish black.
Q: What are glandular hairs?
Glandular hairs are specialized structures that produce essential oils, alkaloids, and other compounds used in medicine. They can be unicellular or multicellular and occur both externally on leaves and internally within plant tissues.
Q: Why is understanding photosynthetic tissue important?
Photosynthetic tissue is crucial for producing food through the combination of carbon dioxide and water into starch, which then converts to sugar at night. This process sustains life in both plants and animals.