Plant Tissue Classification:
Simple Tissues Detailed:
| Property | Parenchyma | Collenchyma | Sclerenchyma |
|---|---|---|---|
| Wall material | Cellulose (primary only) | Pectin + Hemicellulose at corners | Lignin (secondary, uniform) |
| Living/Dead | Living | Living | DEAD at maturity |
| Function | Storage, photosynthesis, buoyancy | Flexibility, support in young organs | Rigidity, mechanical support |
| Location | Throughout (cortex, pith, mesophyll) | Below epidermis, dicot stem, petioles | Seed coats, nut shells, mature stems |
| Subtypes | Chlorenchyma, Aerenchyma | Angular, Lamellar, Lacunar | Fibres, Sclereids (stone cells) |
Complex Tissues Detailed:
| Component | Xylem | Phloem |
|---|---|---|
| Conducting element | Vessels (dead, cylindrical) + Tracheids (dead, tapering) | Sieve tubes (living, enucleated) |
| Support cells | Xylem fibres (dead) | Phloem fibres (dead) = bast fibres |
| Living storage | Xylem parenchyma (ONLY living xylem element) | Phloem parenchyma |
| Metabolic support | — | Companion cells (living, nucleated) |
| Direction of transport | Upward (unidirectional) | Both directions (source → sink) |
| Substance transported | Water + dissolved minerals | Organic solutes (sugars, amino acids) |