PBSci1 Module 4: Basic Plant Parts (Roots, Stems, Leaves)

Vocabulary flashcards covering roots, stems, leaves, plant hormones, and structural modifications from Module 4.

Taproot System

A root system that develops from the growing embryo (radicle) of a germinating seed, growing vertically downwards and producing lateral roots; present in dicot plants and gymnosperms.

Fibrous Root System

A root system where adventitious roots develop from any part of the plant other than the radicle (usually a stem), common in monocot plants where the primary taproot is short-lived.

Root Cap

A thimble-shaped mass of parenchyma cells covering the tip of each root that protects delicate tissues behind it as the young root tip pushes through soil particles.

Region of Cell Elongation

The root region located above the region of cell division where cells become wider and longer, and whose tissues are permeable to minerals.

Region of Cell Maturation

Also known as the Region of Differentiation or Root Hair Zone, the area where cells mature to form dermal, primary vascular, and ground tissues.

Casparian Strips

Suberin bands on the endodermis cell walls that prevent water from passing through the permeable cell walls.

Passage Cells

Thin-walled endodermal cells that serve as passageways for materials between the cortex and the vascular bundle.

Vascular Cylinder

A collective core of tissues (primary phloem and xylem) lying inside the endodermis that conducts water or food in solution.

Conical Root

A modified taproot that is wider at the top and gradually narrows towards the bottom, resembling a cone, such as in carrot (Daucus carota).

Fusiform Root

A modified taproot that is thicker in the middle and tapers at both ends, giving it a spindle-like shape, such as in radish (Raphanus sativus).

Napiform Root

A modified taproot that is round or bulbous at the top and tapers sharply downward, such as in turnip (Brassica rapa) and beetroot (Beta vulgaris).

Tuberous Root

An adventitious root modification characterized by unevenly swollen and irregularly shaped roots that serve as nutrient storage, as seen in cassava (Manihot esculenta) and sweet potato (Ipomoea batatas).

Fasciculated Roots

Adventitious roots that grow in clusters at the base of the stem, creating a bunch-like appearance, such as in Dahlia (Dahlia pinnata).

Nodulose Roots

Adventitious roots where the tips swell to form nodule-like structures, such as in arrowroot (Maranta arundinacea) and mango ginger (Curcuma amada).

Contractile Roots

Adventitious roots that pull the bulb deeper into the soil over time to protect it, as found in onion (Allium cepa).

Moniliform Roots

Adventitious roots featuring swollen sections at regular intervals that give them a beaded look, found in bitter gourd (Momordica charantia).

Annulated Roots

Adventitious roots with ring-like swellings along their length, as seen in ipecac (Cephaelis ipecacuanha).

Assimilatory Roots

Specialized adventitious roots capable of performing photosynthesis, as found in Tinospora (Giloy) and Taeniophyllum.

Epiphytic Roots

Aerial roots that absorb moisture from the air through a specialized spongy tissue known as velamen, as seen in orchids (Vanda, Dendrobium, Phalaenopsis).

Pneumatophores

Pencil-like respiratory roots that grow vertically above the ground in swampy regions to assist with respiration, as seen in mangroves (Rhizophora, Avicennia).

Haustoria

Sucking parasitic roots that penetrate the host plant's vascular system to draw out nutrients, such as in mistletoe (Viscum album) and Cuscuta (Dodder).

Prop Roots

Large, pillar-like supportive roots emerging from horizontal branches to provide additional support, as seen in the Banyan tree (Ficus benghalensis).

Stilt Roots

Supportive roots growing from the lower nodes of the stem and extending obliquely into the soil for enhanced stability, as seen in sugarcane (Saccharum officinarum).

Buttress Roots

Plate-like wooden fins providing critical mechanical support to stabilize tall or shallowly rooted trees in thin tropical soils, such as in the fig tree (Ficus variegata).

Clinging Roots

Supportive roots that firmly attach to surfaces like walls and tree trunks, as seen in ivy (Hedera helix).

Floating Roots

Roots containing air-filled cavities that help aquatic plants remain buoyant, as seen in water hyacinth (Eichhornia crassipes).

Auxins

Plant hormones that stimulate growth through cell elongation, integral to responses to environmental changes.

Gibberellins

Plant hormones that initiate seed germination and promote stem elongation.

Cytokinin

A plant hormone that stimulates cell division.

Ethylene

A plant hormone responsible for maturation and aging.

Abscisic Acid

A plant hormone involved in the inhibition of cell division and seed dormancy.

Terminal Bud

A bud located at the tip of the stem that grows stems bearing leaves and flowers.

Axillary Bud

A bud found in the leaf axils that grows stems bearing leaves and flowers.

Node

The point on a stem where leaves, branches, or flowers originate.

Internode

The section of the stem located between two nodes.

Lenticel

Small openings or raised spots on the stem surface that allow gas exchange.

Sapwood

The outer region of wood containing functioning secondary xylem.

Heartwood

Non-functioning interior wood that no longer conducts materials and can rot away without affecting tree survival.

Cork Cambium

Also known as phellogen, a continuous cylinder of dividing cells that produces the periderm or outer bark.

Phelloderm

Also known as cork parenchyma, the inner layer produced by the cork cambium that stores water and food.

Rhizome

A thick, horizontal underground stem with distinct nodes and internodes, such as in ginger (Zingiber officinale).

Corm

A solid, swollen vertical underground stem base covered with dry, papery leaf bases, such as in taro (Colocasia esculenta).

Bulb

A condensed, disk-like stem surrounded by thick, fleshy scale leaves storing food, such as in onion (Allium cepa).

Tuber

Swollen ends of underground stem branches containing 'eyes' (buds) for vegetative reproduction, such as in potato (Solanum tuberosum).

Phylloclades

Green, flattened or cylindrical stems that perform photosynthesis and conserve water, typical of succulents like saguaro (Carnegiea gigantea).

Cladodes

Green, branch-like stems consisting of only one or two internodes modified to function as leaves, as in asparagus (Asparagus officinale).

Thorns

Hard, straight, and pointed modified stem branches that protect the plant against herbivores, as in lemon (Citrus limon).

Stem Tendrils

Slender, spirally coiled aerial stem structures sensitive to touch that help climbing plants cling to supports, as in grape (Vitis vinifera).

Runner

A thin sub-aerial stem growing horizontally along the ground surface, rooting at nodes to form new plantlets, as in carabao grass (Paspalum conjugatum).

Stolon

An arching lateral sub-aerial branch growing above ground before touching down to root and produce new shoots, as in strawberry (Fragraria moschata).

Sucker

A sub-aerial branch originating from an underground stem that grows obliquely upward out of the soil to form a new plant, as in mint (Mentha spicata).

Offset

A short, thick lateral branch produced by aquatic plants that bears a rosette of leaves above and roots below, as in water hyacinth (Eichhornia crassipes).

Phyllotaxy

The pattern or arrangement of leaves on a stem, categorized into alternate, opposite, or whorled arrangements.

Alternate Leaf Arrangement

A leaf arrangement where a single leaf arises from each node on opposite sides of the stem.

Opposite Leaf Arrangement

A leaf arrangement where two leaves grow from the same node, positioned directly across from each other.

Whorled Leaf Arrangement

A leaf arrangement where three or more leaves originate from a single node, forming a circular pattern.

Parallel Venation

Leaf venation where primary veins run approximately parallel to one another along the leaf's long axis, characteristic of monocots like banana (Musa spp.).

Reticulated Venation

Leaf venation where smaller veins branch off larger veins to resemble a net, characteristic of eudicots.

Abscission Zone

The specific area at the leaf base where a leaf petiole detaches from the stem during leaf shedding.

Bud Scales

Modified leaves that cover and protect winter buds, such as in Northern Red Oak (Quercus rubra).

Bract

A modified leaf associated with a flower or inflorescence but not part of the flower itself, such as in sunflower (Helianthus annuus).