Anatomy of Flowering Plants

Cards · 53

Apical meristem

Undifferentiated tissue at root and shoot tips that drives primary growth through cell division.

Lateral meristem

Cylindrical secondary meristem, such as vascular and cork cambium, responsible for thickening growth.

Intercalary meristem

Meristematic tissue located at monocot nodes and leaf bases that allows rapid stem elongation.

Parenchyma

Living, thin-walled, versatile ground tissue specialized in photosynthesis, storage, and tissue repair.

Collenchyma

Living ground tissue with irregularly thickened primary walls providing flexible structural support.

Sclerenchyma

Dead, rigid ground tissue with lignified secondary cell walls providing mechanical support.

Sclereids

Short, irregularly shaped sclerenchyma cells with thick lignified walls that provide localized hardness.

Fibers (sclerenchyma)

Long, slender, tapering sclerenchyma cells providing tensile strength to stems and vascular bundles.

Epidermis

Single layer of cells covering primary plant bodies to prevent water loss and physical damage.

Cuticle

Waxy, hydrophobic layer of cutin coating the epidermis to limit transpiration and pathogen entry.

Stoma

Microscopic pore in the epidermis regulated by guard cells for gas exchange and transpiration.

Guard cells

Specialized epidermal cell pairs that swell or shrink via turgor pressure to open and close stomata.

Trichomes

Hairlike epidermal outgrowths that deter herbivores, reflect solar radiation, and reduce water loss.

Xylem

Complex vascular tissue conducting water and dissolved minerals upward from roots to the shoot system.

Tracheids

Elongated, dead xylem cells with tapered ends and pitted walls for water conduction in all vascular plants.

Vessel elements

Wide, hollow, dead xylem cells joined end-to-end via perforation plates, typical of angiosperms.

Phloem

Complex vascular tissue transporting photosynthates and organic solutes bi-directionally.

Sieve tube elements

Living, enucleated conducting cells of angiosperm phloem joined end-to-end by perforated sieve plates.

Companion cells

Nucleated phloem cells connected to sieve tube elements via plasmodesmata to regulate sugar loading.

Vascular bundle

Strand of xylem and phloem, arranged in rings in dicot stems and scattered throughout monocot stems.

Vascular cambium

Lateral meristem generating secondary xylem toward the inside and secondary phloem toward the outside.

Periderm

Protective dermal tissue replacing the epidermis in woody plants, consisting of phellem, phellogen, and phelloderm.

Cork cambium (phellogen)

Lateral meristem producing protective suberized cork cells outwardly and phelloderm inwardly.

Lenticels

Porous raised regions in woody bark enabling gas exchange between internal tissues and the air.

Taproot system

Primary root architecture featuring a dominant central root with lateral branches, typical of dicots.

Fibrous root system

Dense network of equal-sized adventitious roots lacking a primary taproot, typical of monocots.

Root cap

Thimble-like mass of parenchyma cells protecting the root apical meristem and secreting mucilage.

Root hairs

Tubular extensions of root epidermal cells drastically increasing surface area for water absorption.

Root cortex

Parenchymatous ground tissue between the epidermis and vascular cylinder specialized in nutrient storage.

Endodermis

Innermost cortical layer regulating water and solute uptake into the vascular cylinder.

Casparian strip

Impermeable band of suberin in endodermal walls forcing water through symplastic pathways.

Pericycle

Layer of parenchyma inside the endodermis that initiates lateral root formation and secondary growth.

Stele

Central vascular core of stems and roots containing xylem, phloem, and associated tissues.

Node

Region on a stem where leaves, buds, and branching twigs emerge.

Internode

Segment of stem between two successive nodes.

Axillary bud

Dormant meristematic cluster in leaf axils capable of forming vegetative shoots or flowers.

Pith

Central, soft spongy parenchyma tissue in dicot stems responsible for nutrient storage.

Blade (lamina)

Broad, flattened portion of a leaf optimized for light interception and gas exchange.

Petiole

Leaf stalk attaching the blade to the stem, containing vascular strands.

Mesophyll

Ground tissue between leaf epidermises where the majority of photosynthesis occurs.

Palisade mesophyll

Columnar, tightly packed upper mesophyll cells containing abundant chloroplasts for light capture.

Spongy mesophyll

Loosely arranged lower mesophyll with extensive air spaces facilitating gas exchange.

Sepal (calyx)

Outermost sterile floral whorl that encloses and protects the developing flower bud.

Petal (corolla)

Often pigmented, sterile floral whorl adapted to attract specific animal pollinators.

Stamen

Male reproductive organ of a flower consisting of a pollen-bearing anther and a filament.

Anther

Terminal part of the stamen containing four microsporangia where pollen grains develop.

Filament

Slender stalk supporting the anther and positioning it for optimal pollen dispersal.

Carpel (pistil)

Female reproductive organ consisting of an ovary, a supportive style, and a pollen-receptive stigma.

Stigma

Sticky or receptive apical surface of the carpel designed to trap compatible pollen grains.

Style

Elongated neck of the carpel through which pollen tubes grow toward the ovule.

Ovary

Swollen basal portion of the carpel enclosing ovules; develops into the fruit after fertilization.

Ovule

Megasporangium-bearing structure in the ovary that develops into a seed after fertilization.

Endosperm

Triploid nutritive tissue formed by double fertilization to nourish the developing embryo.