Leaves Flashcards by Jorelle Tan

The main photosynthetic organ of most vascular plants

Leaf

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Site of gaseous exchange

Leaf

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take in CO2 and release O2

Phtosynthesis

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take in O2 and release CO2

Respiration

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Where does the leaves develop

Nodes

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Thin, flattened sections that collect sunlight

Blade (lamina)

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The leaves are reduced to spines, and the thick green, fleshy stems are where photosynthesis takes place.

Cacti

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It is the thin stalk that attaches the blade to the stem

Petiole

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Have only one blade and one petiole
Single leaf blade at each node

Simple leaves

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Have several blades, or leaflets, that are joined together and to the stem (through petiole) by several petiolules

Compound leaves

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A leaf that is twice divided into leaflets

Double compound leaves

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The terminal point of the leaf

Tip

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The flattened, green, expanded portion of a leaf

Blade

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Edge of a leaf

Margin

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The most prominent central vein in a leaf

Midrib

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Secondary veins in a leaf

Lateral veins

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The leaf stalk (connects blade to
stem).

Petiole

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Leaf-like appendages (at the base of the petiole of some leaves); they may protect the young leaf and may be modified into spines or tendrils

Stipules

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Blade divided into individual leaflets

Compound leaves

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Secondary leaf of a compound leaf

Leaflet

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An extension of the petiole bearing leaflets

Rachis

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The leaflet stalk

Petiolule

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A leaf with leaflets that are borne on the continuation of the petiole

Pinnately compound

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Leaflets are attached along an extension of the petiole called a rachis; there is a terminal leaflet and therefore an odd number of leaflets.

Odd Pinnately Compound

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Leaflets are attached along an extension of the petiole called a rachis; there is an even number of leaflets

Even Pinnately Compound

The leaflets are also divided into leaflets

Twice Pinnately Compound

Leaflets (usually 5) are attached to the tip of the petiole.

Palmately Compound

Leaf divided into three (3) leaflets

Trifoliate leaf

The blade is attached to the stem by a petiole

Petiolate

The blade is attached directly to the stem without a petiole

Sessile

The leaves wrap around the stem of the plant

Clasping

The leaf blade surrounds the stem below the base, forming a tubular position

Sheating

This type of leaf attachment is commonly found in grasses and monocots

Sheating

Arrangement of veins in a leaf

Leaf venation

- principal veins parallel to the axis of the leaf. - common in monocotyledon plant

Parallel venation

feather-like, net venation with lateral veins extending from a central midrib.

Pinnate venation

finger-like, net venation with several major veins diverging from the union of the petiole and the leaf blade

Palmate venation

Needle shaped

Acicular

Oval shaped, small or no point

Elliptic

Heart-shaped, stem at point

Obcordate

Deep, opposite lobing

Pinnatisect

Tapering to a long point

Acuminate

Hooked or sickle shaped

Falcate

Egg-shaped, narrow at the base

Obovate

Kidney-shaped

Reniform

With spine-like tip

Aristate

Fan shaped

Flabelate

Bluntly tipped

Obtuse

Diamond-shaped

Rhomboid

Heart-shaped, stem in cleft

Cordate

Triangular with basal lobes

Hastate

Circular

Orbicular

Spoon-shaped

Spatulate

Wedge shaped, acute base

Cuneate

Pointed at both ends

Lanceolate

Egg-shaped, wide at base

Ovate

Pointed, barbed base

Spear-shaped

Triangular

Deltoid

Parallel margins, elongate

Linear

Like a hand with fingers

Palmate

Tapering point, awl-shaped

Subulate

With finger-like lobes

Digitate

Deeply indented margins

Lobed

Palmate, divided lateral lobes

Pedate

Squared-off apex

Truncate

With fine hairs

Ciliate

With rounded teeth

Crenate

With symmetrical teeth

Dentate

With fine dentition

Denticulate

Serrate with sub-teeth

Double Serrate

Even, smooth throughout

Entire

Indented, but not to the midline

Lobate

Teeth forward-pointing

Serrate

With fine serration

Serrulate

With wave-like indentations

Sinuate

With sharp stiff points

Spiny

Widely wavy

Undulate

Leaf Apex/Tip shapes

- Acuminate - Acute - Cuspidate - Emarginate - Mucronate - Obcordate - Obtuse - Truncate

Leaf Base Shape

- Acute - Auriculate - Cordate - Hastate - Oblique - Rounded - Sagittate - Tumcate

Is the mode of arrangement of leaves along the plant stem or axis

Leaf Arrangement or Phyllotaxy

phýllon meaning

leaf

táxis meaning

arrangement

Phyllotactic patterns

- Distichous - Decussate - Alternate or spiral - Opposite - Whorled or verticulate - Fascicle or fasciculate

Single leaf arising at each node

Alternate

Leaves occurring in pairs at the node

Opposite

- Also called "two ranked leaf arrangement" - Is a special case of either opposite or alternate leaf arrangement where the leaves on a stem are arranged in two vertical columns on opposite sides of the stem

Distichous

Leaves that stands at right angle to the next upper or lower pair

Decussate

More than two leaves at each node

Whorled

It is a thin, curling part of a plant that attaches itself to a support, or something similar to it, such as a strand of hair

Tendrils

Are actually leaves, and photosynthesis is carried out mainly by the fleshy green stem

Spines

Modified leaves that store water and or nutrients for the plant

Storage leaves

A modified leaf that is associated with a reproductive structure such as a flower, inflorescence axis or cone scale

Bracts

It is interrupted by stomata, which allow CO2 exchange between the surrounding air and the photosynthetic cells within a leaf

Epidermal barrier

It is sandwiched between the upper and lower epidermis

Ground tissue

It is continuous with the vascular tissue of the stem

Vascular tissue

This chemical gives the leaves their green color and transfers light energy to chemical energy

Chlorophyll

Support the structure of the leaf and transport substances to and from the cells in the leaf

Veins

These are small holes on the underside of the leaf that allow gases to diffuse in and out

Stomata

It is a waxy, waterproof layer which cuts down the water lost by evaporation and protects against parasitic fungi.

Cuticle

A single layer of cells that are transparent and contain no chloroplast allowing light to pass straight through.

Upper Epidermis

This layer is made up of palisade cells which contain chloroplasts. This is where most of the photosynthesis takes place.

Palisade Layer

This layer consists of irregularly shaped cells with large air spaces between them allowing gas exchange (diffusion) between stomata and photosynthesizing cells.

Spongy Layer

This layer contains lots of tiny holes or pores called stomata at regular intervals. These allow gases to diffuse in and out of the leaf.

Lower Epidermis

high photosynthesis

Palisade mesophyll

Air spaces for gas and water exchange

Spongy Mesophyll

Leaves that have only 1 type of mesophyll

Monocot

Most monocots have what kind of veins

Parallel veins

Most dicots have what kind of veins

Branching (netted) veins