Lecture 1 – Plant Structures

Objectives Outline the main parts of a plant. Explain how plants are designed. Describe the functions of plants.

Animal or Plant?! The sea slug, Elysia chlorotica, captures chloroplasts from the algae on which it feeds. In addition, it has recently been shown to also have incorporated into its genome some of the genes necessary for photosynthesis to continue in these sequestered chloroplasts. True “green technology” in action to produce a solar powered animal!

1. Write a brief paragraph to explain, what is a plant? Be sure to mention the life cycle 2. World population has increased dramatically in recent times. What has happened to grain production during this time? Has it increased, decreased or stayed the same? Compared to the increase in world population, is there: (a) enough; (b) large surpluses or (c) large deficits in food needed to feed everyone?

Plant Engineering and Design What does a plant need to do? 1.Attachment to ground 2.Water uptake 3.Photosynthesis (food production) 4.Material transport 5.Reproduction: - pollination - seed dispersal

Plant Engineering and Design Plants have a modular design: Organs, Tissues, Tissue Systems Roots Stems Leaves Flowers (=modified stem + leaves) Fruit + Seed

Roots Primary Functions: 1.Attachment to substrate 2.Water and nutrient uptake 3.Transport of water and food 4.Food storage

Roots Primary Functions: 1.Attachment to substrate 2.Water and nutrient uptake 3.Transport of water and food 4.Food storage

Major Functions of Roots

Root Systems

Roots First

See Fig. 1.6, p. 7

Roots First

Mycorrhizae

Adventitious Roots

Big Adventitious Roots = Buttresses

Adventitious Roots – Used for Propagation

Storage Roots

The Shoot System - Stems

The Shoot System - Stems nodes + internodes

The Shoot System - Stems nodes + internodes - Leaves

The Shoot System - Stems nodes + internodes - Leaves blade + petiole

The Shoot System - Stems nodes + internodes - Leaves blade + petiole - Buds

Stems – Functions - Supportive Framework: Leaves and Flowers - Conduction of food and water

Stems – Functions - Supportive Framework: Leaves and Flowers - Conduction of food and water Design Constraints: - Growth, from point source - Cellular composition

Stems – Functions - Supportive Framework: Leaves and Flowers - Conduction of food and water Design Constraints: - Growth, from point source - Cellular composition Result: Mostly cylindrical structures and substructures

Stem – Cylindrical Structure

Pith Vascular Bundle

Specialized Stems

Leaves - Functions 1.Food production (Photosynthesis)

Leaves - Functions 1.Food production (Photosynthesis) - Light absorption - Gas exchanges - Food and nutrient transport

Leaves - Functions 1.Food production (Photosynthesis) - Light absorption - Gas exchanges - Food and nutrient transport 2. Specialized functions in some plants

Leaf – Structure

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