PLANTS

MONOCOTS VS DICOTS

Root Systems Fibrous roots: mat of thin roots (grasses) (MONOCOTS) Taproot: one large, vertical root with smaller lateral roots; stores food (dandelion, carrot) (DICOTS) Adventitious: grow from an atypical location

Shoot System: Stems & Leaves Node Internode Axillary bud: potential to form vegetative branch; usually dormant Terminal bud (inhibits growth of axillary buds- apical dominance)

Shoot System: Leaves Leaves Blade Petiole- joins leaf to node of stem

TISSUE SYSTEMS Dermal (epidermis) – single layer; “skin” ; cuticle Vascular – xylem & phloem Ground– metabolic functions; Pith- in dicots; internal to vascular tissue Cortex- in dicots; external to vascular tissue TISSUE SYSTEMS

XYLEM VESSEL ELEMENTS TRACHEIDS CONDUCTS WATER & MINERALS ONLY UP (ONE WAY) FUNCTIONAL CELLS - DEAD STORAGE & SUPPORT VESSEL ELEMENTS TRACHEIDS Long, tapered, lignin

PHLOEM TRANSPORTS FOOD TWO WAY SIEVE CELLS & COMPANION CELLS

3 Basic Cell Types 1. Parenchyma Thin polyhedral, flexible cell walls “typical”; least specialized metabolic functions synthesize & store food where photosynthesis occurs 1st stage of ALL developing plant cells Palisade, spongy, pith, cortex

3 Basic Cell Types Unevenly thick primary walls Groups or strands 2. Collenchyma Unevenly thick primary walls Groups or strands Support of shoot Do not restrain growth (no lignin) Living, flexible, elongated Strands near surface of cortex in stems, petioles, veins of leaves Uncommon in roots Celery stalk

3 Basic Cell Types 3. Sclerenchyma Thick secondary walls with lignin Support, conduct Rigid walls remain as skeleton Dead, do not elongate Xylem’s vessel elements & tracheids Stone cells Fibers – long, slender, tapered, grouped (hemp, rope) Sclereids – short, irregular shape (gritty pear texture, nutshells/seed coats)

MERISTEMS: growth tissues APICAL MERISTEMS Vertical growth Shoots & roots (mitotic division) LATERAL MERISTEMS Increase diameter VASCULAR CAMBIUM (new xylem & phloem) CORK CAMBIUM (cork)

Primary growth of a root Protection

Dicot Root Monocot Root

Dicot Stem Monocot Stem Note – no cambium

Leaf Structure

VASCULAR CAMBIUM LATERAL GROWTH (new xylem inside, new phloem outside)

SECONDARY GROWTH OF A STEM

ANATOMY OF A THREE YEAR OLD STEM SPRING & SUMMER XYLEM

XYLEM Wood Annual rings Spring/summer xylem Non conducting