Chapter 35: Plant Structure, Growth, and Development

Comprehensive vocabulary flashcards covering plant tissues, organ systems, cellular specialization, and primary versus secondary growth from Campbell Biology Chapter 35.

Organ

A structure consisting of several types of tissues that together carry out particular functions.

Tissue

A group of cells consisting of one or more cell types that together perform a specialized function.

Root

A basic plant organ that anchors the plant, absorbs minerals and water, and stores carbohydrates.

Taproot System

A root system found in most eudicots and gymnosperms consisting of a taproot (the main vertical root) and lateral (branch) roots that arise from it.

Fibrous Root System

A root system typical of monocots consisting of adventitious roots that arise from stem organs and lateral roots that branch from them.

Adventitious Roots

Roots that emerge from non-root organ tissues, such as stems above ground.

Root Hairs

Vast numbers of tiny extensions near the root tip that increase surface area for the absorption of water and minerals.

Stem

A plant organ consisting of an alternating system of nodes, where leaves attach, and internodes, the segments between nodes.

Node

The point along a plant stem at which leaves are attached.

Internode

The stem segment located between successive nodes.

Axillary Bud

A structure located in the upper angle formed by each leaf and the stem that has the potential to form a lateral shoot or branch.

Apical Bud

A bud located near the shoot tip (terminal bud) that causes elongation of a young shoot.

Apical Dominance

The hormonal phenomenon whereby the apical bud inhibits the growth of axillary buds, maintaining dormancy in most axillary buds.

Leaf

The main photosynthetic organ of most vascular plants, typically consisting of a flattened blade and a stalk called the petiole.

Petiole

The stalk that joins a leaf blade to a node of the stem.

Cuticle

A waxy coating on the epidermis of non-woody plants that helps prevent water loss.

Periderm

Protective tissue in woody plants that replaces the epidermis in older regions of stems and roots.

Trichomes

Specialized hair-like outgrowths of the shoot epidermis that can provide defense against insect herbivory.

Xylem

Vascular tissue that conveys water and dissolved minerals upward from roots into shoots.

Phloem

Vascular tissue that transports organic nutrients from where they are produced to where they are needed.

Stele

The collective vascular tissue of a stem or root.

Pith

Ground tissue that is internal to the vascular tissue in a plant stem or root.

Cortex

Ground tissue that is external to the vascular tissue in a plant stem or root.

Parenchyma Cells

Relatively unspecialized plant cells with thin, flexible primary walls and no secondary walls that perform most metabolic functions and retain the ability to divide and differentiate.

Collenchyma Cells

Plant cells grouped in strands with thicker, uneven primary cell walls and no secondary walls, providing flexible support to young shoot parts without restraining growth.

Sclerenchyma Cells

Rigid, non-living plant cells at functional maturity that possess thick secondary cell walls strengthened with lignin for structural support.

Sclereids

A type of sclerenchyma cell that is short, irregular in shape, and heavily lignified.

Fibers

Long, slender sclerenchyma cells arranged in threads to provide structural support.

Tracheids

Elongated, dead water-conducting cells found in the xylem of all vascular plants, through which water flows via pits.

Vessel Elements

Short, wide water-conducting cells with perforated end walls that align end-to-end to form vessels; common to most angiosperms and some gymnosperms.

Sieve-Tube Elements

Alive-at-maturity, sugar-conducting phloem cells that lack organelles to facilitate fluid movement.

Sieve Plates

Porous end walls in sieve-tube elements that facilitate the flow of nutrient-rich fluid between cells.

Companion Cell

A living nucleated cell connected to a sieve-tube element whose nucleus and ribosomes serve both itself and the sieve-tube element.

Indeterminate Growth

A pattern of growth characteristic of plants in which the organism continues to grow throughout its entire life.

Determinate Growth

A growth pattern where an organism or certain organs cease growing upon reaching a specific size.

Apical Meristems

Perpetually embryonic tissues located at root and shoot tips and axillary buds that drive primary growth (elongation).

Lateral Meristems

Cylinders of dividing cells (vascular cambium and cork cambium) extending along the length of roots and stems that facilitate secondary growth (thickening).

Vascular Cambium

A cylinder of lateral meristematic cells that generates secondary xylem (wood) toward the interior and secondary phloem toward the exterior.

Cork Cambium

A lateral meristem that produces a tough, thick periderm to replace the epidermis in woody stems and roots.

Annuals

Flowering plants that complete their entire life cycle from germination to seed production within a year or less.

Biennials

Flowering plants that require two growing seasons to complete their life cycle.

Perennials

Flowering plants that live and reproduce over many years.

Root Cap

A thimble-like mass of cells covering the root tip that protects the apical meristem as it penetrates soil.

Endodermis

The innermost cellular layer of the root cortex that selectively regulates the entry of substances from the soil into the vascular cylinder.

Pericycle

The outermost cell layer of the root vascular cylinder from which lateral roots originate.

Leaf Primordia

Finger-like projections along the flanks of the shoot apical meristem from which leaves develop.

Stomata

Microscopic pores in the leaf epidermis that allow gas exchange ($CO_2$ and $O_2$) between the atmosphere and interior photosynthetic cells.

Guard Cells

Pairs of specialized epidermal cells flanking each stoma that regulate the opening and closing of the stomatal pore.

Mesophyll

The ground tissue system of a leaf located between the upper and lower epidermis, specialized for photosynthesis.

Palisade Mesophyll

The upper photosynthetic layer of eudicot mesophyll consisting of tightly packed, elongated parenchyma cells.

Spongy Mesophyll

The lower layer of eudicot mesophyll featuring loosely arranged parenchyma cells with numerous air spaces for gas exchange.