Anatomy of Flowering Plants: Dicots vs. Monocots
🎯 Vascular Tissue System
- Made of xylem (water transport) and phloem (food transport).
- Together they form vascular bundles.
- Open bundles (dicots): Have cambium between xylem/phloem → can make secondary tissues.
- Closed bundles (monocots): No cambium → no secondary growth.
- Radial arrangement (roots): Xylem & phloem on alternate radii.
- Conjoint arrangement (stems/leaves): Xylem & phloem on same radius (phloem outer side).
🌻 Dicot Root (Sunflower Example)
- Outermost: Epiblema with root hairs → absorbs water 💧
- Cortex: Thin-walled cells with air spaces.
- Endodermis: Innermost cortex layer with waterproof Casparian strips 🛑
- Pericycle: Thick-walled cells → makes side roots & cambium.
- Vascular bundles: 2-4 xylem/phloem patches → later forms cambium ring.
- Pith: Small or absent.
🌾 Monocot Root
- Similar to dicot root except:
- More than six xylem bundles (polyarch) 🚀
- Large, well-developed pith
- No secondary growth ❌
🌿 Dicot Stem
- Epidermis: Outer layer with cuticle, stomata & hairs.
- Cortex:
- Hypodermis: Collenchyma → gives strength 💪
- Parenchyma: Thin-walled cells with air spaces.
- Endodermis: Starch-rich “starch sheath”.
- Pericycle: Sclerenchyma patches above phloem.
- Vascular bundles: Arranged in a ring → conjoint, open, with endarch xylem.
- Pith: Large center with air spaces.
🌴 Monocot Stem
- Hypodermis: Sclerenchyma (tough layer).
- Vascular bundles: Scattered, conjoint, closed.
- Each bundle has sclerenchyma sheath.
- Ground tissue: Parenchyma fills space.
- No phloem parenchyma → has water cavities 💦
🍃 Dicot Leaf (Dorsiventral)
- Epidermis: Waxy cuticle; more stomata on lower side.
- Mesophyll:
- Palisade: Tightly packed columnar cells (top) → main photosynthesis ☀️
- Spongy: Loose cells with air cavities (bottom).
- Vascular bundles: In veins; size varies; bundle sheath present.
- Xylem faces top, phloem faces bottom.
🌱 Monocot Leaf (Isobilateral)
- Stomata equally on both sides ⚖️
- Mesophyll NOT divided into palisade/spongy.
- Bulliform cells on top: Turgid → leaf open; flaccid → leaf curls (saves water) 🔄
- Vascular bundles nearly same size → parallel veins.
💎 NEET Super-Short Notes
| Feature | Dicot | Monocot |
|---|---|---|
| Vascular Bundles | Open, in a ring (stem) | Closed, scattered |
| Secondary Growth | Yes (cambium present) | No |
| Root Xylem Bundles | 2-4 | >6 (polyarch) |
| Leaf Stomata | Mostly lower surface | Both surfaces |
| Bulliform Cells | Absent | Present |
🌟 Key Takeaways
- Plants have 3 tissue systems: Epidermal (skin), Ground (filler), Vascular (transport).
- Dicots = Secondary growth ✅, Monocots = No secondary growth ❌.
- Casparian strips in roots control water entry!
- Monocot stems: Vascular bundles look like “islands in a sea” 🌊
- Leaf anatomy matches function: Dicots = sun-catching, Monocots = water-saving!
You’ve got this! Remember: Roots anchor, stems support, leaves feed 🌿✨
