BOTAFUN: Plant Tissues and Vegetative Organs

Plant Body

The collective term for stems, roots, and leaves of a plant.

Meristem

Region of undifferentiated cells where active cell division drives plant growth.

Primary (Apical) Meristem

Meristem responsible for increase in length; found at shoot and root apices.

Secondary (Lateral) Meristem

Meristem that increases diameter/girth; includes vascular cambium and cork cambium.

Shoot Apex

Apical meristem at the tip of a stem that drives shoot elongation.

Root Apex

Apical meristem at the tip of a root that drives root elongation.

Vascular Cambium

Lateral meristem that produces secondary xylem (wood) inward and secondary phloem outward.

Cork Cambium

Lateral meristem that produces protective cork cells of the periderm.

Protoderm

Primary meristem that differentiates into the epidermis.

Procambium

Primary meristem that differentiates into primary xylem and phloem.

Ground Meristem

Primary meristem that differentiates into parenchyma, collenchyma, and sclerenchyma.

Dermal Tissue

The outer protective tissue layer of plants, chiefly the epidermis; a simple tissue.

Ground Tissue

Bulk of the plant body; includes parenchyma, collenchyma, and sclerenchyma.

Vascular Tissue

Conductive tissues xylem and phloem responsible for transport of water, minerals, and sugars.

Simple Tissue

Plant tissue composed of a single cell type (e.g., dermal or ground tissues).

Complex Tissue

Plant tissue composed of two or more cell types (e.g., xylem, phloem, periderm).

Parenchyma

Living, thin-walled cells that perform photosynthesis, storage, secretion, and can divide.

Collenchyma

Living cells with unevenly thickened walls providing flexible support for growing organs.

Sclerenchyma

Dead at maturity; thick lignified walls give rigid support; includes fibers and sclereids.

Chlorenchyma

Parenchyma rich in chloroplasts; main site of photosynthesis in leaves.

Storage Parenchyma

Parenchyma specialized for storing starch, often in roots.

Aerenchyma

Parenchyma with large air spaces facilitating gas exchange in aquatic plants.

Stellate Parenchyma

Star-shaped aerenchyma common in aquatic plants for buoyancy and aeration.

Sclereid

Short, irregular sclerenchyma cell with very thick walls; contributes to hardness of shells and pits.

Fiber

Long, slender sclerenchyma cell arranged in threads; provides tensile strength.

Xylem

Vascular tissue that conducts water and dissolved minerals upward; contains vessels, tracheids, fibers, parenchyma.

Phloem

Vascular tissue that transports sugars and organics; contains sieve-tube members, companion cells, fibers, parenchyma.

Periderm

Secondary protective tissue composed of cork cambium and cork; replaces epidermis in woody stems and roots.

Secretory Structure

Plant tissue that produces and stores substances like latex, resins, and nectar.

Vessel Member

Wide, short xylem element with perforation plates; forms continuous tubes for rapid water movement.

Tracheid

Long, tapered xylem cell with pits; conducts water and provides support.

Root

Generally underground organ that anchors, absorbs water/nutrients, and stores food.

Radicle

Embryonic root present in a seed.

Root Cap

Loose layer of cells protecting the root apex and sensing gravity.

Root Hair

Unicellular epidermal extension that increases root surface area for absorption.

Endodermis

Innermost cortex layer of roots regulating entry of water and solutes into the stele.

Casparian Strip

Band of suberin in endodermal walls forcing water through cell membranes before entering xylem.

Pericycle

Layer just inside endodermis that gives rise to lateral roots.

Symplast

Continuous cytoplasmic pathway interconnected by plasmodesmata for substance movement.

Apoplast

Continuum of cell walls and intercellular spaces through which water moves freely.

Taproot System

Root system with one main primary root and smaller lateral branches.

Fibrous Root System

Root system with many similarly sized adventitious roots; common in monocots.

Pneumatophore

Specialized aerial root in swamp trees facilitating gas exchange with submerged roots.

Buttress Root

Flared, plank-like root bases supporting tall tropical trees.

Prop Root

Adventitious root arising from stem that provides extra support (e.g., corn).

Contractile Root

Root that shortens to pull plant organs deeper into the soil (e.g., bulbs).

Photosynthetic Root

Root capable of photosynthesis, found in some orchids.

Mycorrhiza

Symbiotic association between a fungus and plant root enhancing mineral uptake.

Root Nodule

Swelling on legume roots housing nitrogen-fixing Rhizobium bacteria.

Parasitic Root

Modified root that penetrates host plants to obtain nutrients (e.g., dodder).

Propagative Root

Root that produces adventitious buds/shoots for asexual reproduction.

Stem

Plant axis bearing leaves and buds; conducts and supports.

Node

Stem region where leaves or branches attach.

Internode

Segment of stem between two nodes.

Apical Bud

Terminal bud at stem tip containing the shoot apex.

Axillary Bud

Bud in the axil of a leaf that may develop into a branch or flower.

Shoot Apex Meristems

Protoderm, procambium, and ground meristem located at stem tip.

Secondary Growth

Increase in stem/root thickness due to vascular and cork cambia activity.

Wood

Accumulated secondary xylem inside vascular cambium.

Bark

All tissues external to vascular cambium: secondary phloem plus periderm.

Sapwood

Younger, light-colored outer wood actively conducting water.

Heartwood

Old, dark central wood no longer conducting; provides structural support.

Lenticel

Spongy opening in periderm allowing gas exchange in woody organs.

Thorn

Modified stem formed into a sharp point for defense.

Tendril (Stem)

Slender, coiling stem modification aiding support (e.g., grape).

Cladophyll

Flattened photosynthetic stem resembling a leaf.

Stolon (Runner)

Horizontal aboveground stem that forms new plants at its nodes.

Sucker

Shoot arising from an underground stem or root near parent plant.

Tiller

Basal branch in grasses arising from the main stem.

Offset

Short, horizontal shoot forming a small plantlet (e.g., pineapple).

Tuber

Fleshy, enlarged end of a rhizome storing starch (e.g., potato).

Bulb

Short stem with fleshy storage leaves; underground bud (e.g., onion).

Rhizome

Horizontal underground stem serving in storage and asexual reproduction (e.g., ginger).

Corm

Short, vertical, swollen underground stem for storage (e.g., crocus).

Monocot Leaf

Long, narrow leaf with parallel venation; undifferentiated isobilateral mesophyll.

Dicot Leaf

Broad leaf with netted venation; differentiated palisade and spongy mesophyll.

Simple Leaf

Leaf with single blade per petiole.

Compound Leaf

Leaf divided into leaflets arising from one axillary bud.

Pinnately Compound

Leaflets arranged along an extension of the petiole (rachis).

Palmately Compound

Leaflets radiate from a single point at petiole tip.

Parallel Venation

Veins run side by side; typical of monocots.

Netted Venation

Veins form a branching network; typical of dicots.

Phyllotaxy

Pattern of leaf arrangement on a stem.

Opposite Phyllotaxy

Two leaves arise at the same node on opposite sides.

Alternate Phyllotaxy

Single leaf per node arranged alternately along stem.

Whorled Phyllotaxy

Three or more leaves arise from a single node forming a ring.

Rosette

Circular cluster of leaves at ground level with very short internodes.

Amplexicaul

Leaf base clasps the stem.

Perfoliate

Stem appears to pass through the leaf blade.

Connate

Pair of opposite leaves fused around the stem.

Peltate

Petiole attached to blade center, umbrella-like (also spelled peltrate).

Sheathing Leaf Base

Leaf base wraps partly around stem, common in grasses.

Bulliform Cell

Large epidermal cell in monocot leaves that aids leaf folding to reduce water loss.

Trichome

Hair-like epidermal outgrowth reducing water loss and deterring herbivores.

Guard Cell

Paired epidermal cell controlling stomatal opening.

Stomata

Pores in epidermis regulating gas exchange; open via guard cell turgor.

Phototropin

Blue-light receptor protein in guard cells that triggers stomatal opening.

Mesophyte

Plant adapted to environments with moderate water availability.

Halophyte

Plant adapted to saline habitats; often shows succulence and salt tolerance.

Hydrophyte

Plant adapted to freshwater or aquatic habitats; often with air spaces and thin cuticle.