chapter 30

Plant growth characteristics

Plants can form new organs and grow throughout their life.

Hierarchical organization in vascular plants

Structure: Cells → Tissues → Organs.

Main organs of angiosperms

Stem, leaves, and roots.

Function of root and shoot systems

Function together in organ systems.

Meristems

Growth driven by cell division at meristems.

Primary & Secondary Growth

Results in production of repeated modules, allowing plants to grow taller and thicker.

Shoot apical meristems

Enable modular growth by continuously producing new tissues.

Zone of cell elongation

Forms as cells away from the shoot tip stop dividing but continue to elongate.

Evolution of leaves

Leaves evolved from flattened branches for photosynthesis.

Adaptations influencing leaf diversity

Surface area for photosynthesis, CO2 uptake needs, water conservation, thermoregulation, and disease defense.

Specialized functions of leaves

Protection, climbing, insect trapping, and pollinator attraction.

Vascular connections in leaves

Leaves need to connect with xylem and phloem in stems to grow efficiently.

Floral meristems

Develop from shoot meristems and do not allow for continued growth.

Functions of roots

Obtain water and nutrients and anchor plants.

Root apical meristem

Growth occurs from root apical meristem, protected by a root cap.

Structure of roots

Includes root epidermis, cortex, and endodermis.

Endodermis in roots

Plays a critical role in nutrient absorption along with root hairs.

Monocots root system

Form fibrous root systems through primary growth.

Storage in roots, stems, and leaves

Examples include beets (roots), tubers like potatoes (stems), and bulbs like onions (leaves).

Plant secondary growth

Diameter increase necessary for stability and support.

Lateral meristems

Vascular cambium produces new xylem and phloem; cork cambium maintains the bark layer.

Growth rings in wood

Indicate growth rates; wider rings reflect favorable conditions, while narrow rings suggest stress.

Bark formation

Composed of nonliving cork cells with lenticels for gas exchange, limiting oxygen diffusion.