Plant Structure, Function, and Diversity: Study Notes for General Biology

Plant Structure and Function

Root and Shoot Systems

The plant body is organized into two main systems: the root system and the shoot system. Each system has specialized functions essential for plant growth and survival.

• Root System: Anchors the plant in the soil, absorbs water and minerals, and often stores food. Roots can be larger than the shoot system in some plants.

• Shoot System: Includes stems, leaves, and reproductive structures. Responsible for photosynthesis, transport of nutrients, and reproduction.

• Example: In a radish plant, the root system stores nutrients and anchors the plant, while the shoot system supports leaves and flowers.

Vascular Plants

Major Groups of Vascular Plants

Vascular plants possess specialized tissues (xylem and phloem) for transporting water, minerals, and nutrients. They are divided into two major groups:

• Gymnosperms: Plants with seeds not enclosed in fruit (e.g., pines, firs).

• Angiosperms: Flowering plants with seeds enclosed in fruit (e.g., roses, sunflowers).

• Example: Conifers are gymnosperms, while grasses and orchids are angiosperms.

Evolutionary Timeline of Vascular Plants

Vascular plants evolved over millions of years, with angiosperms being the most recent and diverse group.

• Key evolutionary events: Development of seeds, flowers, and fruit.

• Additional info: Angiosperms dominate most terrestrial ecosystems due to their efficient reproductive strategies.

Angiosperms: Monocots vs. Eudicots

Comparison of Monocots and Eudicots

Angiosperms are divided into two major clades: monocots and eudicots. These groups differ in several anatomical and physiological features.

Feature	Monocots	Eudicots
Cotyledons	One	Two
Leaf Venation	Usually parallel	Usually netlike
Flower Parts	Usually in multiples of three	Usually in multiples of four or five
Vascular Bundle Arrangement	Scattered	In a ring
Root System	Fibrous	Taproot
Pollen	One pore or furrow	Three pores or furrows
Examples	Grasses, orchids, lilies, palms	Maples, oaks, roses, beans, sunflowers

Plant Organization

Shoot and Root System Structure

Plants are organized into shoot and root systems, each with distinct organs and functions.

• Shoot System: Composed of stems, leaves, and flowers. Responsible for photosynthesis and reproduction.

• Root System: Composed of primary and lateral roots. Responsible for anchorage and absorption.

Root System Functions and Types

Functions of the Root System

The root system serves several vital functions for the plant.

• Anchorage: Roots secure the plant in the soil.

• Absorption: Roots take up water and minerals from the soil.

• Storage: Some roots store nutrients (e.g., carrots, beets).

Types of Root Systems

Plants exhibit different root system architectures, adapted to their environment and needs.

• Taproot System: Consists of a primary root with lateral roots. Common in eudicots (e.g., carrots, beetroots, radishes).

• Fibrous Root System: Many roots of similar size, common in monocots (e.g., grasses).

• Example: Carrots and beetroots have taproot systems, while grasses have fibrous root systems.