plant body

Plant Body

·       Morphology and Anatomy:

o   Morphology refers to external organization, while anatomy pertains to internal organization.

o   Plant ancestors were single-celled and aquatic, resembling green algae.

o   Transition to terrestrial life led to greater complexity and specialization.

·       Form Facilitates Function:

o   Plant structures evolved for specific functions.

o   Roots are for water and mineral uptake.

o   Shoots are for photosynthesis and reproduction.

o   Notable feature: dynamic architecture with continual growth.

·       Morphology:

o   Systems include roots and shoots.

o   Organs within the shoot system are stems, leaves, and buds.

·       Root Form and Function:

o   Functions include anchorage, absorption of water and minerals, and storage.

o   Forms include tap, fibrous, and adventitious roots.

·       The Shoot:

o   Comprises the stem, leaf, and bud.

o   Buds are sources of new growth, either terminal or axillary.

o   Modular organization for support, transport, and storage.

·       Variation in Stem Morphology:

o   Stems can be rhizomes, bulbs, runners, or tubers.

·       Leaves:

o   Function primarily for photosynthesis.

o   Morphology is broad and flattened for efficient gas uptake and light absorption.

·       Variation in Leaf Morphology:

o   Different leaf types include tendril, spine, bract, and fleshy leaves.

o   Each leaf possesses one axillary bud.

·       Anatomical Complexity:

o   Seed plants exhibit greater anatomical complexity compared to primitive plants like bryophytes.

o   Bryophytes have simpler anatomy with a single-layer thickness of photosynthetic structures.

·       Plant Cells:

o   Basic cell components include nucleus, mitochondria, ribosomes, Golgi apparatus, endoplasmic reticulum, cytoplasm, and plasma membrane.

o   Special Features of Plant Cells:

·       Chloroplasts for photosynthesis.

o   Large vacuole for storage.

o   Cell wall for structural support.

o   Plasmodesmata for cell communication.

·       Cell Division and Wall Formation:

o   Plant cells undergo cell division, forming new walls.

o   All new walls start as primary walls, with the possibility of adding secondary walls later.

·       Plant Cell Types:

o   Parenchyma cells are living and have a primary cell wall, involved in diverse metabolic processes.

o   Sclerenchyma cells (fibers, sclereids) have thick secondary walls strengthened with lignin, providing support and rigidity.

·       Transport Tissues and Cells:

o   Xylem conducts water and minerals, comprising tracheids and vessel elements.

o   Phloem conducts food, consisting of sieve elements and companion cells.

·       Xylem and Phloem:

o   Together, xylem and phloem make up vascular tissue in plants.

o   Xylem transports water and minerals, while phloem transports sugars.

·       Tissue Functions:

o   Transport of water and minerals, support, and conducting cells are essential functions.

o   Tracheids and vessel elements transport within xylem.

o   Sieve elements are involved in phloem transport.

·       Plasmodesmata:

o   Plasmodesmata are communication channels between sieve elements and companion cells.