3.7

Shoot System

Comprises the vegetative (leaves and stems) and reproductive (flowers, fruits) portions of a plant.

Root System

Supports the plant and absorbs water and nutrients from the soil.

Meristematic Tissue

Undifferentiated, actively dividing cells responsible for plant growth.

Apical Meristems

Located at the tips of roots and shoots, responsible for primary (length) growth.

Lateral Meristems

Allow vascular plants (gymnosperms and dicots) to grow in girth (thickness).

Intercalary Meristematic Tissue

Specific to monocots (e.g., grasses), allowing growth from the base of the leaf blade.

Permanent Tissues

Tissues that have differentiated and are no longer actively dividing.

Dermal Tissue

Covers the outer surface of the plant, like skin (epidermis), protecting against desiccation and regulating gas exchange.

Cuticle

A protective waxy layer secreted by the epidermis to prevent water loss (desiccation).

Stomata

Openings in dermal tissue for gas exchange (CO₂ intake, H₂O release), regulated by guard cells.

Trichomes

Hair-like projections on the plant surface that reduce water loss, reflect solar energy, and deter herbivores.

Root Hairs

Extensions of dermal tissue that increase root surface area for efficient water absorption.

Vascular Tissue

Comprised of xylem and phloem, vital for plant transport systems.

Xylem

Transports water and minerals; composed of dead cells (tracheids and vessel elements) at maturity, strengthened by lignin.

Phloem

Conveys sugars, hormones, and nutrients; composed of sieve-tube elements supported by companion cells.

Lignin

A structural molecule that provides support to xylem.

Ground Tissue

Fills space between other tissues, involved in photosynthesis and the storage of starch.

Primary Growth

Vertical growth occurring in all vascular plants at apical meristems.

Secondary Growth

Increased girth or thickness, occurring in gymnosperms and dicots due to lateral meristems.

Cambium

Meristematic tissue located below the bark, crucial for secondary growth by producing secondary xylem.

Sapwood

Lighter layer of a tree that still conducts water, composed of dead xylem cells.

Heartwood

Older, darker central part of a tree that no longer conducts water but provides structural support.

Growth Rings

Formed in temperate climates based on seasonal growth changes; larger, lighter cells in spring, smaller, darker cells in fall.