Unit 4 Ch 35 Vascular Plant Structure, Growth, and Development Flashcards

Comprehensive vocabulary flashcards covering the structural hierarchy, growth mechanisms, and developmental processes of vascular plants as detailed in Chapter 35.

Root

An organ that anchors a vascular plant in the soil, absorbs minerals and water, and often stores carbohydrates and other reserves.

Primary root

The first root (and first organ) to emerge from a germinating seed, originating in the seed embryo.

Lateral roots

Branches that emerge from the primary root to enhance the root system's ability to anchor the plant and acquire resources.

Taproot system

A root system consisting of one main vertical root that develops from the primary root, typically found in tall, erect plants with large shoot masses.

Fibrous root system

A thick mat of slender roots spreading out below the soil surface, characterizing most monocots; it is efficient at anchoring plants and preventing soil erosion.

Adventitious

A term describing a plant organ that grows in an unusual location, such as roots arising from stems or leaves.

Root hairs

Thin, finger-like extensions of root epidermal cells that increase the surface area of the root for the absorption of water and minerals.

Stem

A plant organ bearing leaves and buds whose chief function is to elongate and orient the shoot to maximize photosynthesis.

Nodes

The points on a stem at which leaves are attached.

Internodes

The stem segments located between nodes.

Apical bud

The growing shoot tip where most of the growth of a young shoot is concentrated.

Axillary bud

An element located in the upper angle formed by each leaf and the stem that has the potential to form a lateral branch, thorn, or flower.

Rhizome

A horizontal shoot that grows just below the surface.

Stolon

Horizontal shoots, also known as "runners," that grow along the surface and enable a plant to reproduce asexually.

Tubers

Enlarged ends of rhizomes or stolons specialized for storing food, such as potatoes.

Leaf

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

Petiole

The stalk that joins the leaf to the stem at a node.

Dermal tissue system

The outer protective covering of the plant that forms the first line of defense against physical damage and pathogens.

Epidermis

A layer of tightly packed cells that serves as the dermal tissue in nonwoody plants.

Cuticle

A waxy epidermal coating on leaves and most stems that helps prevent water loss.

Periderm

Protective tissues that replace the epidermis in older regions of stems and roots in woody plants.

Guard cells

Specialized epidermal cells in shoots involved in gaseous exchange via stomata.

Trichomes

Hairlike outgrowths of shoot epidermis that can reduce water loss, reflect excess light, or defend against insects.

Vascular tissue system

A system composed of xylem and phloem that facilitates the transport of materials and provides mechanical support.

Xylem

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

Phloem

Vascular tissue that transports sugars from where they are made to where they are needed or stored.

Stele

The collective term for the vascular tissue of a root or stem.

Ground tissue system

Tissues that are neither dermal nor vascular, specialized for functions such as storage, photosynthesis, and support.

Pith

Ground tissue that is internal to the vascular tissue.

Cortex

Ground tissue that is external to the vascular tissue.

Cell differentiation

The process by which cells become specialized in structure and function during development.

Parenchyma cells

Relatively undifferentiated cells with thin primary walls that perform most metabolic functions, such as photosynthesis and starch storage.

Collenchyma cells

Elongated cells with unevenly thickened primary walls that provide flexible support to young parts of the plant shoot without restraining growth.

Sclerenchyma cells

Rigid supporting cells with thick secondary walls containing large amounts of lignin.

Lignin

A relatively indigestible strengthening polymer present in the secondary cell walls of all vascular plants, accounting for more than a quarter of the dry mass of wood.

Tracheids

Tubular, elongated water-conducting cells in the xylem that are dead and lignified at functional maturity; found in all vascular plants.

Vessel elements

Wider, shorter xylem cells aligned end to end to form long pipes called vessels; present in most angiosperms.

Sieve-tube elements

Living sugar-conducting cells of the phloem in angiosperms that lack a nucleus, ribosomes, and a distinct vacuole to facilitate nutrient flow.

Companion cell

A nonconducting cell alongside a sieve-tube element, connected by plasmodesmata, whose nucleus and ribosomes serve both cells.

Indeterminate growth

A process where growth occurs throughout the plant's life because of undifferentiated tissues called meristems.

Meristems

Undifferentiated tissues containing cells that can divide, leading to new cells that elongate and differentiate.

Apical meristems

Meristems located at root and shoot tips that enable primary growth, or growth in length.

Lateral meristems

Cylinders of dividing cells (vascular cambium and cork cambium) that enable secondary growth, or growth in thickness.

Vascular cambium

A lateral meristem that adds secondary xylem (wood) and secondary phloem.

Cork cambium

A lateral meristem that replaces the epidermis with thicker, tougher periderm.

Root cap

A thimble-like structure that protects the root apical meristem as the root pushes through the soil.

Endodermis

A cylinder one cell thick that forms the innermost layer of the root cortex and acts as a selective barrier regulating passage into the vascular cylinder.

Pericycle

The outermost cell layer in the vascular cylinder from which lateral roots arise.

Stomata

Epidermal pores flanked by guard cells that allow the exchange of $CO_2$ and $O_2$ between the air and photosynthetic cells.

Mesophyll

The ground tissue of a leaf, specialized for photosynthesis and consisting of palisade and spongy layers.

Dendrochronology

The science of analyzing tree growth ring patterns.

Heartwood

Older layers of secondary xylem that no longer transport water and minerals, typically located closer to the center of a stem or root.

Sapwood

The newest, outer layers of secondary xylem that still transport xylem sap.

Bark

All tissues external to the vascular cambium, including secondary phloem, the most recent periderm, and all older layers of periderm.

Lenticels

Small, raised areas in the periderm containing more space between cork cells, enabling gas exchange for living cells within woody organs.

Developmental plasticity

The ability of an organism to alter its form in response to local environmental conditions.

Morphogenesis

The process that gives a tissue, organ, or organism its shape and determines the positions of cell types.

Pattern formation

The development of specific structures in specific locations.

Phase changes

The morphological changes that arise from transitions in shoot apical meristem activity, such as the shift from a juvenile to an adult stage.

ABC hypothesis

A model proposing that three classes of genes (A, B, and C) direct the formation of the four types of floral organs: sepals, petals, stamens, and carpels.