Plant Tissues and Growth: A Comprehensive Study Guide

Apical Meristems

Regions at plant tips for growth.

Shoot Apical Meristem (SAM)

Promotes upward and outward plant growth.

Root Apical Meristem (RAM)

Facilitates downward root growth.

Primary Meristems

Tissues formed from apical meristems.

Protoderm

Forms the dermal tissue system.

Ground Meristem

Forms the ground tissue system.

Procambium

Forms the vascular tissue system.

Tissue

Group of structurally/functionally distinct cells.

Simple Tissue

Composed of one cell type.

Complex Tissue

Composed of multiple cell types.

Tissue System

Group of tissues functioning as a unit.

Ground Tissue System

Derived from ground meristem.

Vascular Tissue System

Derived from procambium.

Dermal Tissue System

Derived from protoderm.

Eustele

Arrangement of vascular bundles in stems.

Protostele

Arrangement of vascular tissue in roots.

Parenchyma

Simple tissue, alive at maturity, thin walls, intercellular spaces, (photosynthesis, secretions, regeneration, short distance water movement (ray parenchyma), re differentiation

Collenchyma

Simple tissue, living cells, thickened primary walls, elongated to run parallel to length of organ, not in monocot stems, supports young growing organs to fight gravity, found as strands or cylinders in stems, petioles, large veins of leaves

Sclerenchyma

Simple tissue, dead at maturity, thick secondary walls, supports plants that are no longer elongating

Fibers

Long, thin sclerenchyma cells for support.

Sclereids

Irregular sclerenchyma cells providing hardness.

Epidermis

Protective outer layer of plant.

Cuticle

Waxy layer reducing water loss.

Trichomes

Hair-like structures on plant surfaces.

Trichomes

Hair-like projections on epidermis for protection, absorb water and minerals from air, slows water loss, defend against insects

Stomata

Pores for gas exchange in leaves.

Guard Cells

Cells controlling stomatal opening and closing.

Xylem

Complex tissue for long-distance water transport.

Transpiration

Water vapor loss from leaves through stomata.

Tracheary Elements

Cells that conduct water in vascular plants.

Negative Pressure

Pressure driving water movement in xylem.

Tracheid

Elongated cells for water transport in xylem with pit pairs

Pit-Pair

Adjoining pits between neighboring tracheids.

Vessel Element

Wider cells in angiosperms for efficient water flow both pit pairs and perforation plates.

cavitate more easily

Cavitation

Separation of water column in tracheary elements.

Embolism

Air pocket disrupting water transport in plants.

Protoxylem

First xylem to develop from procambium.

Metaxylem

Second xylem to develop from procambium.

Phloem

Complex tissue transporting sugars and nutrients.

Sieve Cells

Found in gymnosperms for nutrient transport, longer more slender overlapping, with seive areas, with albuminous cells

Sieve Tube Elements

Found in angiosperms for sugar transport, shorter and wider with seive areas and sieve plates (larger then sieve areas)

P-Proteins

Proteins aiding in sealing and repair of sieve cells.

Root System Functions

Anchors, absorbs, conducts, stores sugars water minerals metabolites like nicotine, and clonal regeneration.

Primary Phloem

Source of sieve elements from procambium.

Sieve Plate Pores

Openings for material movement between sieve cells.

Clonal Regeneration

Ability of roots to regenerate new plants.

Taproot System

One main root with lateral roots branching off. (fist root produced + tap root)

penetrates deeper then fibrous root system

Fibrous Root System

Multiple roots of similar size and age.

Root System Plasticity

Roots adapt in size, distribution, and architecture.

Fine Root Tips

Locations where water enters the root system.

Root Depth

Most roots found in upper 2 feet of soil. except desert shrub penetrates 174 ft and acacia tree penetrates 98ft

Desert Shrub Roots

Mesquite roots penetrate deep in arid conditions.

Root Cap Regions

Includes lateral root cap and columella.

Lateral Root Cap Function

Secretes mucilage and produces border cells.

Columella Function

Perceives and responds to gravity.

Mucilage

Lubricant that reduces soil friction for roots.

Border Cells

Secrete mucilage, aiding root movement.

Gravitropism

Roots grow downwards in response to gravity.

Auxin (IAA) Role

Inhibits root cell growth, causing downward bending.

Apical Meristem

Region producing new cells in root growth.

Promeristem

Least differentiated part of the apical meristem.

Quiescent Center

Region of slow-dividing initials in roots.

Cell Differentiation Process

Cells divide, elongate, and specialize in roots.

Driving Force for Roots

Turgor pressure and cell elongation push roots.

Maturation Indicator

Presence of root hairs indicates mature roots.

Mature Root Regions

Includes epidermis, cortex, and vascular bundle.

Epidermis Function

First layer of root, protects and absorbs.

Cortical Parenchyma Functions

Mainly involved in storage within roots.

Aerenchyma Structure

Forms from dead cells under low oxygen.

Water Movement Pathways

Includes apoplastic, symplastic, and transmembrane routes.

Endodermis Role

Regulates water movement into vascular tissue.

Casparian Strips

Prevent passive flow of water into xylem.

Transmembrane pathway

Water crosses cell membranes to enter cells.

Endodermis

Layer with Casparian strips blocking apoplastic route.

Casparian strips

Waxy barriers ensuring selective mineral uptake.

Primary xylem

Differentiates centripetally from outside to inside.

Protoxylem

First xylem formed, small and flexible cells.

Metaxylem

Later formed xylem, larger and thick-walled.

Xylem pole

Cluster of primary xylem in vascular cylinder.

Diarch

Root classification with two xylem poles.

Triarch

Root classification with three xylem poles.

Primary phloem

Located outside of primary xylem.

Pericycle

Surrounds vascular tissue, origin of lateral roots.

Lateral root formation

Roots arise from pericycle opposite protoxylem poles.

Destructive process

Lateral roots push through cortex during emergence.

Adventitious roots

Roots arising from the stem, e.g., English ivy.

Pneumatophores

Air roots found in aquatic plants.

Storage taproots

Enlarged roots storing sugars and starch.

Bulbs

Layers of leaves storing food.

Corm

Stem structure storing food.

True tubers

Stems modified for storage.

Shoot system

Composed of leaves and stem.

Phytomer

Repeating unit of nodes, internodes, and buds.

Anticlinal division

Cell division adding cells across surface.

Periclinal division

Cell division adding layers of cells.

Tunica-corpus organization

Structure of shoot apical meristem in eudicots.

Leaf primordium

Underdeveloped cells that become leaves.

Eustele

Vascular arrangement with discrete bundles.

Procambium

Differentiates to form primary xylem and phloem.

Protophloem

Early phloem formed during plant development.