Senna is an important medicinal plant known for its use as a laxative. Below are the detailed morphological and microscopical characters of Senna:



Morphological Characters:

  1. Leaves:

    • Shape: Pinnate compound, with leaflets arranged in pairs (4–5 pairs per leaf).
    • Color: Green to pale green.
    • Size: Leaflets are 2–5 cm long, lanceolate or oblong in shape, with an acute apex and an asymmetrical base.
    • Surface: Smooth with prominent veins on the underside.
    • Odor: Characteristic, faint.
    • Taste: Slightly bitter.

  2. Flowers:

    • Shape: Yellow, arranged in racemes.
    • Size: Small, with 5 petals and 10 stamens.
    • Calyx: Green with five sepals.
    • Corolla: Yellow and slightly zygomorphic (bilaterally symmetrical).

  3. Fruit:

    • Type: Legume or pod.
    • Size: 5–7 cm long, flattened, and slightly curved.
    • Color: Light brown when mature.
    • Seeds: Hard, brown, and oblong in shape.

  4. Stem:

    • Shape: Erect, smooth, and cylindrical.
    • Color: Green to light brown.
    • Size: Can grow up to 1–2 meters in height.

Microscopical Characters:

  1. Leaf Epidermis:

    • Upper Epidermis: Contains rectangular cells with a smooth cuticle.
    • Lower Epidermis: Presence of stomata (anisocytic type), with more stomata on the lower surface.
    • Trichomes: Non-glandular and multicellular trichomes are present, especially on the lower epidermis.

  2. Vascular Bundle:

    • Midrib: Contains a crescent-shaped vascular bundle.
    • Xylem: Located towards the upper surface, and phloem is towards the lower surface.
    • Parenchyma: Ground tissue surrounding the vascular bundle consists of parenchymatous cells.

  3. Mesophyll:

    • Palisade Cells: The upper half of the mesophyll contains compactly arranged palisade parenchyma.
    • Spongy Parenchyma: Below the palisade, loose, spongy parenchyma is present, which helps in gas exchange.

  4. Calcium Oxalate Crystals:

    • Raphides and prisms of calcium oxalate are observed in the parenchymatous tissues.

These features are critical for identifying and differentiating Senna from other medicinal plants during quality control and pharmacognostic studies.