BOTAFUN - Plant Anatomy & Physiology

This set of vocabulary flashcards covers key anatomical structures, tissue systems, modifications, and physiological concepts related to roots, stems, leaves, and water transport discussed in the lecture.

Root

The usually underground main axis of a plant that anchors, absorbs, stores, and links the plant to the soil.

Taproot System

Root system with one main vertical primary root and smaller lateral roots; common in many dicots.

Fibrous Root System

Root system consisting of many roots of similar size that spread out near the soil surface; typical of most monocots.

Adventitious Roots

Roots that arise from organs other than the radicle, such as stems or leaves.

Radicle

The embryonic primary root that emerges first during seed germination.

Root Cap

A mass of loosely arranged parenchyma cells protecting the root tip as it pushes through soil.

Root Apical Meristem

The region of actively dividing cells behind the root cap that generates primary root tissues.

Protoderm

Primary meristem that differentiates into the epidermis of roots and shoots.

Procambium

Primary meristem that forms the primary xylem and phloem.

Ground Meristem

Primary meristem that produces cortex and pith tissues.

Region of Elongation

Root zone where cells enlarge mainly in length, contributing to root growth.

Region of Maturation

Root zone where cells differentiate and root hairs appear; also called root-hair zone.

Root Hair

Epidermal outgrowth that increases root surface area for absorption.

Epidermis (Root)

Outermost, generally uncutinized root cell layer permeable to water and minerals.

Cortex (Root)

Parenchyma tissue between epidermis and stele, often storing starch and allowing solute movement.

Endodermis

Innermost cortical layer whose suberized Casparian strips regulate solute entry into stele.

Suberin

Waxy, water-impermeable substance impregnating endodermal walls.

Casparian Strip

Band of suberin in endodermal radial walls that blocks apoplastic flow.

Stele

Central vascular cylinder of the root containing pericycle, xylem, and phloem.

Pericycle

Outer layer of the stele that can resume division and gives rise to lateral roots.

Xylem

Vascular tissue of thick-walled vessels/tracheids that transports water and minerals upward.

Phloem

Living vascular tissue (sieve-tube elements & companion cells) that translocates organic nutrients.

Secondary Growth

Increase in girth via vascular cambium and cork cambium activity in woody stems/roots.

Vascular Cambium

Lateral meristem producing secondary xylem inward and secondary phloem outward.

Cork Cambium (Phellogen)

Lateral meristem that forms protective cork (phellem) and sometimes phelloderm.

Phellem (Cork)

Protective outer tissue of stems/roots composed of dead, suberized cells.

Periderm

Collective term for cork cambium, cork, and phelloderm replacing epidermis in woody organs.

Sapwood

Younger, outer functional xylem that conducts water.

Heartwood

Older, inner nonfunctional xylem clogged with resins/tannins; darker in color.

Annual Ring

Layer of springwood plus summerwood produced by vascular cambium in one growing season.

Springwood

Early-season xylem with large, thin-walled cells formed when water is abundant.

Summerwood

Late-season xylem with smaller, thicker-walled cells formed under drier conditions.

Storage Root

Root modified to store carbohydrates or water (e.g., sweet potato).

Pneumatophore

Aerial root growing upward for gas exchange in water-logged soils (e.g., mangroves).

Velamen Root

Orchid aerial root with multilayered epidermis reducing water loss.

Prop Root

Adventitious aerial root that braces and stabilizes tall stems (e.g., corn).

Buttress Root

Large, flared root at trunk base providing support in shallow soils.

Stem

Main aboveground axis supporting leaves, flowers, and transporting water, minerals, and food.

Node

Stem region where leaves or branches are attached.

Internode

Stem segment between two nodes.

Petiole

Leaf stalk connecting blade to stem.

Axillary Bud

Dormant shoot located in the axil that may develop into branch, flower, or thorn.

Terminal Bud

Bud at stem apex responsible for lengthwise growth.

Leaf Scar

Mark on stem where a leaf was previously attached, containing bundle scars.

Bundle Scar

Small marks inside a leaf scar indicating former vascular connections.

Lenticel

Corky stem opening that permits gas exchange in woody stems.

Stipule

Paired appendage at leaf base that may be leaf-like or scale-like.

Shoot Tip

Growing point at stem apex containing apical meristem and leaf primordia.

Leaf Primordium

Young developing leaf arising from shoot apical meristem.

Collenchyma

Living support tissue with unevenly thickened, plastic walls in young stems.

Sclerenchyma

Thick-walled, often lignified support tissue (fibers, sclereids) providing rigidity.

Vascular Bundle

Strand of xylem and phloem (and enclosing sheath) within stem or leaf.

Bundle Cap Fibers

Sclerenchyma fibers capping vascular bundles in herbaceous dicot stems.

Pith

Central parenchyma region in many stems; may be hollow in some species.

Pith Ray

Radial parenchyma strip between vascular bundles, facilitating lateral transport.

Phloem Ray

Radial parenchyma band within phloem conducting nutrients laterally.

Xylem Ray

Radial parenchyma band in xylem connecting to rays in phloem.

Bark

All tissues outside vascular cambium, i.e., periderm plus phloem.

Wood

Accumulated secondary xylem in a woody stem or root.

Trichome

Epidermal hair; may be glandular or non-glandular, serving protection, secretion, or water retention.

Rhizome

Horizontal underground stem with nodes, buds, and scale leaves (e.g., ginger).

Corm

Short, vertical, swollen underground stem serving as storage organ (e.g., gladiolus).

Bulb

Underground storage stem with fleshy scale leaves surrounding a short shoot (e.g., onion).

Tuber

Enlarged, nutrient-storing stem tip bearing nodes and buds (e.g., potato).

Stem Tendril

Slender, coiling stem modification aiding climbing.

Runner

Aboveground horizontal stem (stolon) that roots at nodes, forming new plants (e.g., strawberry).

Stolon

Subsurface or surface horizontal stem that can generate new shoots away from parent.

Cladode

Single flattened stem node/internode functioning as a photosynthetic leaf.

Phylloclade

Flattened stem segment comprising several nodes and internodes acting like a leaf.

Leaf (General)

Lateral shoot organ specialized for photosynthesis; consists of blade and often petiole.

Blade (Lamina)

Flattened light-harvesting portion of a leaf.

Simple Leaf

Leaf with a single undivided blade, which may be lobed.

Compound Leaf

Leaf divided into separate leaflets attached to a single petiole.

Pinnately Compound Leaf

Leaflets arranged along both sides of a central rachis.

Palmately Compound Leaf

Leaflets radiate from one point at petiole tip like fingers on a hand.

Rachis

The main axis of a pinnately compound leaf bearing leaflets.

Sheath

Basal part of many monocot leaves that encircles the stem.

Auricle

Ear-like lobe at junction of sheath and blade in some grasses.

Ligule

Thin outgrowth from the leaf sheath inner surface in some monocots, protecting against debris.

Phyllotaxy

Pattern of leaf arrangement on a stem (alternate, opposite, whorled, etc.).

Alternate (Spiral)

One leaf per node, successive leaves forming a spiral up the stem.

Distichous

Alternate leaves arranged in two opposite rows.

Opposite

Two leaves attached opposite each other at a node.

Decussate

Opposite leaf pairs arranged at right angles to those above and below.

Whorled

Three or more leaves attached at the same node.

Venation

Pattern of veins in a leaf blade.

Pinnate Venation

One major midvein with secondary veins branching like a feather.

Palmate Venation

Several primary veins radiating from leaf base.

Parallel Venation

Many nearly parallel veins typical of monocots.

Midrib

Central primary vein of a pinnate leaf.

Cuticle

Waxy cutin layer covering epidermis, reducing water loss.

Dorsiventral Leaf

Leaf with structurally distinct upper (adaxial) and lower (abaxial) surfaces.

Isobilateral Leaf

Leaf with similar anatomy on both surfaces, common in many monocots.

Mesophyll

Photosynthetic ground tissue between leaf epidermal layers; includes palisade and spongy parenchyma.

Palisade Layer

Columnar mesophyll cells rich in chloroplasts just below upper epidermis.

Spongy Layer

Loosely arranged mesophyll with large air spaces aiding gas exchange.

Vascular Bundle Sheath (Leaf)

Layer of cells surrounding xylem and phloem within a leaf vein.

Bulliform Cell

Large thin-walled epidermal cell in some grasses that aids leaf rolling in drought.

Reproductive Leaf

Leaf that bears plantlets along margins for vegetative propagation (e.g., Kalanchoe).

Storage Leaf

Leaf modified to store water or carbohydrates, often succulent.