OIA2007 CELL TYPES & INCLUSION

Meristematic Cells

Small, isodiametric, thin-walled cells with large nuclei.

Actively divide (e.g., root & shoot tips, cambium).

Permanent Tissues

Derived from meristems; lose division ability.

Two types: Simple (e.g., parenchyma) and Complex (xylem, phloem).

Parenchyma

Living, thin-walled cells with air spaces; perform photosynthesis & storage.

Collenchyma

Living, thickened at corners (uneven cellulose); support in growing shoots & leaves.

Sclerenchyma

Dead cells with lignified walls; two types: fibres & sclereids.

Fibres

Long, slender cells.

Examples: Flax, jute, hemp, Cinchona bark (diagnostic features: large, funnel-shaped lumen).

Sclereids (Stone Cells)

Short, thick-walled; e.g., in pear (Pyrus communis).

Types: Brachysclereids (Pyrus communis - pear), Astrosclereids (water lily), Osteosclereids (cinnamon bark) & irregular sclereid (wild cherry bark)

Xylem Components

Vessels, tracheids (water conduction), fibres (support), parenchyma (storage).

Xylem Lignin Patterns

Annular, Spiral, Scalariform (male fern rhizome), Reticulate (Gentian root, Rhubarb), Bordered Pitted (Liquorice root).

Phloem Components

Sieve-tube members (conduct), Companion cells (support, regulate).

Sieve Plates

Perforated ends connecting sieve tubes, enabling nutrient transport.

Epidermis

Protective, continuous outer layer; may contain crystals, papillae, trichomes.

Cuticle

Fatty cutin layer on epidermis; can be striated (diagnostic).

Stomata Types

Anomocytic (Digitalis), Anisocytic (Belladonna), Paracytic (Senna), Diacytic (Vasaka).

Guard Cells

Regulate stomatal opening via turgor pressure.

Trichomes Definition

Epidermal outgrowths; can be unicellular or multicellular, glandular or non-glandular.

Glandular Trichomes

Found in Hyoscyamus, Belladonna, Digitalis.

Non-Glandular Trichomes

Protective, reduce water loss; found in Senna, Anise.

Cicatrix

Scar left behind when trichome detaches—diagnostic marker.

Ground Tissues Functions

Photosynthesis, storage, support, secondary growth.

Ground Tissues Found In

Pith, cortex, mesophyll, endosperm.

Ergastic Substances

Non-living cell products: reserve, excretory, and secretory.

Reserve Carbohydrates

Starch (potato, rice), inulin (Dahlia), cellulose.

Starch Grain Shapes

Maize: polyhedral, Potato: ovoid, Ginger: sac-like.

Multicompound Starch

Seen in Ipecacuanha.

Starch Staining

Blue-violet with iodine, shows hilum, concentric rings

Proteins

In amorphous (Maize) or crystalline (Castor) forms (e.g., aleurone grains).

Lipids

Reserve oils (liquid/solid); e.g., Castor oil.

Mucilage

Present in epidermis, stains pink with ruthenium red (e.g., Senna, Isapgol).

Examples of Excretory Products

Alkaloids, tannins, glycosides, resins, volatile oils, calcium salts.

Calcium Oxalate Crystals

Types: prisms, clusters, needles, crystal sand (microsphenoids).

Prisms

One prism per Parenchyma cell (form sheath around fibres), found in Cascara, Senna, Liquorice

Crystal Sand (Microsphenoids)

Tiny crystals found in Atropa belladonna.

Rosette/Cluster Crystals

Found in Stramonium, Rhubarb, Senna.

Needle-Shaped Crystals

Acicular type in Ipecacuanha, Squill.

Examples of Secretory Products

Enzymes, pigments (e.g., chlorophyll, anthocyanins, flavonoids), nectar.

Enzyme Functions

Breakdown of carbs, proteins, lipids.

Pigments

Photosynthesis (chlorophyll), coloration (flavonoids, anthocyanins).

Nectar

Secreted to attract pollinators.

Diagnostic Value of Inclusions

Used to identify crude drugs by starch, crystals, trichomes, sclereids.