Roots and Leaves Vocabulary

Vocabulary-style flashcards covering key terms from the Roots and Leaves lecture notes.

Morphology

The study of the physical form and external structure of plants, including observation and classification of plant organs and their arrangement; useful for taxonomy and systematics.

Anatomy

The study of tissues and cell structures of plant organs, with microscopic examination to understand cell types, functions, and their roles in physiology, growth, and adaptation.

Root system functions

The main roles of roots: anchorage to soil, support of the shoot system, absorption of water and minerals, and storage of food; balance with the shoot for water and mineral supply.

Rhizosphere

The thin area around roots where complex chemistry occurs for nutrient absorption.

Root apical meristem (RAM)

The region at the tip where cells divide to form primary meristematic tissue, protected by the root cap.

Zone of division

Region of active cell division that creates primary meristematic tissues; located near the RAM.

Zone of elongation

Region where newly divided cells grow longitudinally while cell walls remain flexible.

Zone of maturation

Region where root hairs form and the root starts absorbing water and minerals; branching begins here.

Root cap

Protective cap at the tip of the root that shields the RAM and is continually renewed.

Quiescent center

Area of the RAM that divides at an extremely slow rate.

Pericycle

Outer boundary of the vascular cylinder; site for lateral root initiation and development.

Lateral root primordia

Lateral root primordia form when the pericycle divides; as they grow, they push aside cortex and epidermis and endodermal cells enclose the new root.

Procambium

Primary meristem that differentiates into vascular tissue (xylem and phloem) in the vascular cylinder.

Ground meristem

Primary meristem that differentiates into cortex and pith (ground tissue).

Protoderm

Outer primary meristem that gives rise to the epidermis.

Epidermis (root)

Outer boundary of the root, a single layer of cells derived from the protoderm; often forms root hairs to increase absorption.

Cortex

Several cell layers between the epidermis and the vascular cylinder; mainly parenchyma; inner boundary is the endodermis.

Endodermis

Innermost layer of the cortex, a single row of cells surrounding the vascular tissue that helps regulate mineral accumulation and contains the Casparian strip.

Casparian strip

A waxy band in endodermal cell walls that forces water movement through living cells (regulated by the plasma membrane).

Exodermis

A potential outer cortical layer present in some species, located outside the endodermis.

Vascular cylinder

Central region differentiated from the procambium, consisting of primary xylem, primary phloem, and the pericycle.

Primary xylem

Xylem formed during primary growth responsible for water transport.

Primary phloem

Phloem formed during primary growth responsible for transporting sugars.

Protoxylem

First xylem elements to mature; capable of transporting water while elongating; usually has annular or helical secondary walls.

Metaxylem

Xylem that matures after elongation is complete; forms thick secondary walls for water and mineral transport.

Tracheids

Water-conducting xylem cells with tapered ends and pits.

Vessel elements

Xylem cells that align end-to-end to form vessels for efficient water transport.

Sieve tubes

Phloem cells that form sieve tubes for transport of sugars and other photosynthates.

Companion cells

Cells that accompany sieve tube elements and aid in phloem transport.

Phelloderm

Parenchyma layer inside the cork, part of the periderm.

Cork cambium

Secondary meristem that produces cork (phellem) as part of the periderm.

Cork

Dermal tissue forming the outer bark, produced by the cork cambium.

Dermal tissue

Protective tissue that includes epidermis and its derivatives (cuticle, trichomes, guard cells).

Vascular cambium

Secondary meristem between xylem and phloem that produces secondary xylem and secondary phloem during growth.

Ground tissue

Tissue between epidermis and vascular tissue; mainly parenchyma and supportive cells derived from ground meristem.

Periderm

Outer protective tissue formed by cork cambium, cork, and phelloderm; replaces the epidermis in mature regions.

Bark

Protective outer layers of stems and roots formed by secondary phloem and periderm.

Leaf primordia

Crescent-shaped bumps produced on the side of the shoot apical meristem that give rise to true leaves.

Phyllotaxis

Pattern of leaf production and arrangement on the stem.

Leaf blade

Broad, flat portion of the leaf where most photosynthesis occurs.

Mesophyll

Middle leaf tissue between the epidermal layers, consisting of chloroplast-containing cells organized into palisade and spongy tissue.

Palisade tissue

Elongated, chloroplast-rich cells in the upper mesophyll; primary site of photosynthesis.

Spongy tissue

Lower mesophyll with loosely arranged cells that facilitate gas diffusion; contains some chloroplasts.

Guard cells

Paired cells that surround stomata and control opening size by changing shape.

Stomata

Pores that regulate gas exchange; opened or closed by guard cells.

Cuticle

Waxy layer on leaf surfaces that minimizes water loss.

Trichomes

Hair-like structures on leaves that can secrete substances; contribute to pubescence.

Veins

Leaf vascular bundles forming a network that contains xylem and phloem.

Xylem

Water-conducting tissue composed of tracheids and vessel elements (when present).

Phloem

Sugar-conducting tissue formed by sieve tubes with companion cells.