Plant Tissue Systems and Cell Types

A set of 50 vocabulary flashcards covering plant tissue systems, cell types, organs, and growth processes.

Ground tissue system

Plant tissue system that includes all tissues neither dermal nor vascular; functions in storage, support, photosynthesis, and production of oils/toxins.

Parenchyma cells

Living filler cells with thin primary walls; perform photosynthesis, gas exchange, and carbohydrate storage.

Collenchyma cells

Living support cells with unevenly thickened primary walls; provide flexible structural support to growing parts.

Sclerenchyma cells

Dead, thick-walled, lignified support cells (fibers or sclereids) forming the main structural framework of plants.

Vascular tissue system

Conductive “plumbing” system composed of xylem and phloem that moves water, minerals, and sugars.

Xylem

Dead, thick-walled tissue (wood) that transports water and mineral ions upward and helps support stems.

Phloem

Living, thin-walled tissue (bark) that transports sugars (sap) both up and down the plant.

Dermal tissue system

Protective outer covering of a plant body composed mainly of epidermis (or periderm in older organs).

Epidermis

Single layer of parenchyma cells covering leaves, stems, and roots; reduces water loss and secretes cuticle.

Cuticle

Waxy layer secreted by epidermis that minimizes water loss by transpiration.

Stomata

Pores in leaf epidermis through which gases (CO₂, O₂, water vapor) are exchanged.

Guard cells

Sausage-shaped epidermal cells flanking each stoma; regulate opening and closing to control water loss.

Meristematic tissue

Regions of actively dividing cells that generate new tissues and enable plant growth.

Apical meristem

Meristem at tips of roots and shoots responsible for primary (lengthwise) growth.

Intercalary meristem

Meristem located at internodes or leaf bases (common in grasses) allowing regrowth after cutting or grazing.

Lateral meristem

Meristem (vascular cambium and cork cambium) that produces secondary tissues and increases girth.

Root cap

Protective mass of cells covering the root apical meristem, aiding penetration through soil.

Zone of cell division

Root region containing actively dividing meristematic cells that produce new root tissues.

Zone of elongation

Root region where recently formed cells elongate, pushing the root tip deeper into soil.

Zone of maturation

Root region where cells complete differentiation and become fully functional (often with root hairs).

Cortex

Ground tissue between epidermis and vascular cylinder in roots and stems; often stores starch.

Endodermis

Single innermost layer of cortex that regulates movement of water and solutes into the vascular cylinder.

Pericycle

Outermost layer of vascular cylinder; gives rise to lateral roots and contributes to secondary growth.

Vascular cylinder (stele)

Central core of xylem and phloem in a root enclosed by the endodermis.

Procambium

Primary meristem that differentiates into primary xylem and primary phloem.

Vascular cambium

Lateral meristem located between xylem and phloem that produces secondary xylem inward and secondary phloem outward.

Cork cambium

Lateral meristem that generates periderm (cork and phelloderm), replacing epidermis in older organs.

Periderm

Protective tissue produced by cork cambium comprising cork, cork cambium, and phelloderm.

Secondary growth

Increase in diameter of stems and roots due to activity of vascular and cork cambia.

Primary growth

Lengthwise growth of roots and shoots resulting from activity of apical meristems.

Annual ring

Ring of secondary xylem formed in a single growing season; visible in cross-section of woody stems.

Heartwood

Older, central secondary xylem that no longer conducts water; often darker and stronger.

Node

Point on a stem where leaves, branches, or buds are attached.

Internode

Stem segment between two successive nodes.

Vascular bundle

Discrete strand of xylem (inner) and phloem (outer) in stems and leaves.

Tracheids

Elongated, dead xylem cells with tapered ends and pits; conduct water and provide support.

Vessel elements

Wide, dead xylem cells stacked end-to-end to form continuous vessels for efficient water transport.

Sieve tube elements

Living phloem cells lacking nuclei that align end-to-end to transport sugar-rich sap.

Companion cells

Nucleated phloem cells that control and maintain adjacent sieve tube elements.

Mesophyll

Photosynthetic ground tissue of a leaf located between upper and lower epidermis.

Palisade mesophyll

Columnar, chloroplast-rich cells beneath upper epidermis of dicot leaves specialized for photosynthesis.

Spongy mesophyll

Loosely arranged leaf cells with air spaces facilitating gas diffusion; located below palisade layer.

Bundle sheath

Layer of cells surrounding a leaf’s vascular bundle, regulating substance exchange with mesophyll.

Hypodermis

Supporting tissue layer just beneath epidermis, often composed of collenchyma or sclerenchyma cells.

Pith

Central parenchymatous ground tissue found in many stems.

Root hair

Tubular extension of a root epidermal cell that increases surface area for water and mineral absorption.

Dicot (eudicot)

Angiosperm with two cotyledons, netlike leaf venation, vascular bundles in a ring, taproot, and floral parts in fours or fives.

Monocot

Angiosperm with one cotyledon, parallel venation, scattered vascular bundles, fibrous roots, and floral parts in threes.

Ground meristem

Primary meristem that gives rise to ground tissues (parenchyma, collenchyma, sclerenchyma).

Protoderm

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