2026-05-13 18:55

Status: #new

Tags: #biology #plants

Plant Organs

Roots

Root Function

• Water and dissolved mineral uptake
• Plant anchorage
• Carbohydrate, water and nutrient storage

Root Structure

• Root Cap $\to$ the tip of the root that protects growing tissues and can extend through resistant materials
• Cortex $\to$ Vascular Tissue is centralized in the centre of the root
  • Dermal tissue forces water towards the cortex
• Monocot xylem tubes are in a ring
• Dicot xylem tubes are in a x-shape

Stems

Stem Types

Tubers

• Enlarged portions of underground stems

Bulbs

• Short underground stems

Corm

• Short underground stems

Stolons

• Horizontal stems above the ground

Rhizomes

• Horizontal stems found underground
  A key difference between bulbs and corms is that bulbs have layers, both are papery on the outside, both are found underground, corms are more solid.

Monocot vs Dicot Stems

• Vasc. bundles scattered in Monocot, Dicot is a circular structure

Stem roots and applications

Tap root

• A single thick root in Dicots that grows deep into the soil

Fibrous root

• Many smaller shallow roots that maximize surface area

Stem Structure

• Stems support leaves and reproductive structure
• Associated with vertical structures with consistent diameter

Grafting

• Exposes vascular tissues, so you can put a new plant to create a new plant

Roots vs Stems

• This is done through cross examining plant tissues. The type of cell in which the bulging structure enlarges determines classification.

Leaves

• Leaves appear in a variety of sizes and patterns. They share similar placements of cellular tissue.

Epidermal and Phloem structures

• Epidermal cells secrete a waxy substance to generate a cuticle layer.
  • Reduces evaporation rate
• Between the top and bottom epidermal layers are ground cells which are responsible for photosynthesis.

Mesophyll Types

• Palisade Mesophyll $\to$ Tightly-packed tall cells at the top of the leaf
• Spongy Mesophyll $\to$ Loosely packed, round cells below the palisade mesophyll

Vascular Phloem

• Vascular bundles contain xylem and phloem, and run through the leaf for water and nutrient exchange

Monocot vs Dicot

• Monocots have parallel vein structures
• Dicots have branching vein structures

Simple Leaves

• Are a single structure. They may be a single blade or they may haves or they may be divided

Compound Leaves

• Compound leaves consist of multiple petioles (leaf stalks) extending from the main stem.
  • A leaf of a compound leaf is a "leaflet"

References