General Botany: Tissues, Overview, Leaves, and Roots

Comprehensive vocabulary flashcards covering plant tissues, stem primary growth and modifications, leaf anatomy and physiological pathways, and root systems and specialized adaptations.

Division Magnoliophyta

The botanical division comprising all flowering plants, informally known as angiosperms.

Chlorenchyma

Specialized photosynthetic parenchyma cells with thin primary walls that allow light and carbon dioxide to pass through to the chloroplasts.

Transfer Cells

Parenchyma cells that mediate short-distance transport of material, characterized by an extensive plasma membrane with numerous molecular pumps.

Collenchyma

A plant tissue composed of cells with primary cell walls that are thin in some areas and thickened in others, providing plastic support to growing organs.

Sclerenchyma

Plant tissue with a primary wall and a thick, usually lignified secondary wall that provides elastic support and mechanical strength.

Fibers

Long, flexible, slender mechanical sclerenchyma cells that usually occur in bundles and reinforce plant tissues.

Sclereids

Short, isodiametric (cuboidal), inflexible, and brittle mechanical sclerenchyma cells found in nutshells, seed coats, and plant tissue.

Phyllotaxy

The specific arrangement of leaves on a plant stem.

Decussate Phyllotaxy

A leaf arrangement where two leaves are attached at each node in an opposite arrangement, with each successive pair positioned at a right angle of $90^\text{o}$ to the previous pair.

Stolons

Horizontal, above-ground modified stems with long, thin internodes that allow for the dispersal of daughter plants.

Corms

Vertical, thick modified stems covered with thin, papery leaves.

Rhizomes

Fleshy horizontal stems that grow underground and allow a plant to spread vegetative growth.

Cutin

A fatty substance that coats the outer tangential walls of epidermal cells, making them impermeable to water.

Trichomes

Epidermal cells that elongate outward into hair-like structures to deter herbivory, minimize water loss, protect from solar radiation, or function as secretory glands.

Aerenchyma

Cortical parenchyma tissue loosely packed with large intercellular air spaces.

Circular Bordered Pits

The most derived and strongest pit type in tracheary elements, characterized by a circular cross-section and a thickened rim formed by a border of extra wall material over the pit chamber.

Sieve Area

Clusters of enlarged plasmodesmata pores (sieve pores) on the cell wall of sieve elements that interconnect adjacent living protoplasts.

Companion Cells

Active cells adjacent to sieve tube members in angiosperms that feature a prominent nucleus and dense cytoplasm filled with ribosomes, supplying metabolic support and loading sugars.

Protoxylem

The first primary xylem to differentiate in the subapical meristem, featuring extensible annular and helical wall thickenings to accommodate ongoing cell elongation.

Protoderm

The outermost primary meristem formed by the apical meristem that gives rise to the epidermis.

Ground Meristem

The primary meristem that gives rise to ground tissues, including the cortex and pith.

Procambium

The primary meristem that differentiates into primary vascular tissues (primary xylem and primary phloem).

Totipotency

The concept in cell theory noted by Gottlieb Haberlandt that any single plant cell has the potential to give rise to a complete plant.

Perianth

The collective term for the non-reproductive envelope of a flower, consisting of the sepals (calyx) and petals (corolla).

Determinate Growth

Genetically programmed growth that stops once an organ reaches a specific, limited size, typical of leaves, flowers, and fruits.

Indeterminate Growth

Unlimited growth occurring throughout the lifespan of a plant due to active meristems, typical of root and shoot systems.

Tropism

A plant growth response toward or away from a directional environmental stimulus, such as light, gravity, or touch.

Nastic Movement

A non-growth movement response of a plant that occurs independently of the direction of the stimulus, typically driven by changes in turgor pressure.

Hemiparasites

Parasitic plants that contain chlorophyll and produce part of their own glucose through photosynthesis while obtaining water and minerals by penetrating host stems or roots.

Holoparasites

Non-photosynthetic parasitic plants that have lost their chloroplast genomes entirely and rely on host plant roots for water, minerals, and organic nutrients.

Urushiol

The toxic defensive chemical compound produced by poison ivy that causes severe allergic reactions upon contact.

Retting

The processing step in linen production where harvested flax plants are exposed to moisture to break down pectins binding stem fibers together.

Adaxial Surface

The upper (ventral) surface of a leaf blade specialized for capturing sunlight.

Abaxial Surface

The lower (dorsal) surface of a leaf blade, typically containing a higher concentration of stomata.

Abscission Zone

A specialized region at the base of a petiole or leaf where cells produce enzymes to cut off the leaf at the end of its functional life, forming a corky protective leaf scar.

Rachis

The central axis extension of the petiole in a pinnately compound leaf to which individual leaflets are attached by petiolules.

Kranz Anatomy

The specialized leaf internal structure found in C4 plants, characterized by large chlorophyllous bundle sheath cells tightly wrapping veins surrounded by an outer ring of mesophyll cells.

Stomatal Crypts

Deep epidermal depressions on the lower leaf surface of xerophytic plants (such as Nerium oleander) that contain stomata and trichomes to trap non-moving air and reduce transpiration.

Root Cap

A thimble-like layer of protective cells covering the root apical meristem that paves the way through soil and detects gravity using starch grains.

Mucigel

A polysaccharide-rich substance secreted by dictyosomes near the tip of the root cap that lubricates passage through soil and fosters beneficial bacterial growth.

Quiescent Center

A mitotically inactive central region within the root apical meristem that acts as a cell reserve to replace damaged meristematic cells.

Casparian Strip

A waterproof band of suberin and lignin encrusting the radial and tangential walls of endodermal cells that forces water and minerals to pass symplastically into the vascular cylinder.

Apoplastic Transport

The movement of water and dissolved minerals purely through cell walls and non-living intercellular spaces.

Symplastic Transport

The movement of water and solute molecules through the living cytoplasm of cells via plasmodesmata connections.

Pericycle

The outermost layer of parenchyma cells within the root vascular cylinder (stele), located interior to the endodermis, where lateral root primordia originate.

Passage Cells

Slow-to-mature endodermal cells that retain only Casparian strips, remaining un-suberized on their tangential walls to allow fluid passage into the stele.

Velamen

A specialized, thick, waterproof epidermal layer found on the aerial roots of epiphytic orchids that prevents water loss during dry conditions.

Contractile Roots

Specialized roots that shrink vertically and expand radially in their cortex cells, pulling bulbs, corms, or seeds to optimal soil depths.

Ectomycorrhizae

A symbiotic association between plant roots and fungi where fungal hyphae penetrate between outer root cortex cells without penetrating the cell walls.

Endomycorrhizae

A symbiotic association between plant roots and soil fungi where fungal hyphae penetrate through root cortical cell walls into the space adjacent to the plasma membrane.

Haustoria

Highly modified parasitic plant roots that penetrate host tissues to establish vascular connections and absorb nutrients and water.