Cinchona, a well-known medicinal plant used for its alkaloids, particularly quinine, has distinctive morphological and microscopical characters that help in its identification. Here's a breakdown of these features:



Morphological Characters:

  1. Plant Type: Cinchona is a small to medium-sized evergreen tree or shrub.
  2. Bark:
    • The bark, which is the main medicinal part, is rough, grayish to brown in color, and can be up to 2 cm thick.
    • It is aromatic with a bitter taste due to the presence of quinine and other alkaloids.
    • When dried, the bark becomes brittle and can be easily powdered.
  3. Leaves:
    • The leaves are simple, opposite, elliptical to lanceolate in shape, and have a smooth margin.
    • They are dark green on the upper side and lighter beneath, with prominent veins.
  4. Flowers:
    • The flowers are small, tubular, and pink to red in color, forming terminal panicles.
  5. Fruit:
    • The fruit is a capsule that contains numerous small seeds.

Microscopical Characters:

  1. Cork Cells:
    • The outermost layer of the bark consists of a thick layer of cork cells. These cells are rectangular in shape and are arranged in radial rows.
  2. Parenchyma:
    • The secondary cortex or parenchyma cells are large, thin-walled, and filled with starch grains, which can be observed under the microscope.
  3. Stone Cells (Sclereids):
    • Scattered throughout the bark are stone cells or sclereids, which are thick-walled, lignified cells that provide mechanical support. These are often irregularly shaped.
  4. Medullary Rays:
    • These are radial bands of parenchyma cells extending from the central vascular tissue towards the outer cortex. They help in the transport of nutrients.
  5. Phloem Fibers:
    • The bark also contains fibers of the phloem, which are long, spindle-shaped cells providing tensile strength. They are often lignified.
  6. Calcium Oxalate Crystals:
    • Cinchona bark contains numerous calcium oxalate crystals, usually in the form of rosettes or prisms.
  7. Vascular Bundles:
    • The vascular bundles are scattered and include phloem with sieve tubes and companion cells, which are essential for the transport of organic substances.

These characters are essential for the identification and authentication of Cinchona bark, especially in the pharmaceutical industry where it's used for extracting alkaloids like quinine, used to treat malaria.