Exercise No. 14 The Leaf (Theoretical)

Leaf

Main photosynthetic organ of plants.

Mesophyll

Photosynthetic parenchyma cells strategically located within the blade of the leaf.

Lamina

The flat, light harvesting portion of the leaf.

Abaxial surface

The lower or ventral side of the leaf blade.

Adaxial side

The upper or ventral surface of the leaf blade.

Midrib

The large central vascular tissue from the leaf. Veins arise from it and supply the blade.

Petiole

A stalk that attaches the lead to the node of the stem.

Sessile

Is when a leaf has no petiole.

Leaf sheath

A clasping structure that attaches monocot leaves to their stems. Encircles the whole stem, thus causing nodes of monocots to appear ringlike on their stems.

Simple parallel venation

Is a type of venation where the veins run parallel to the midrib. Is found in Bambusa sp.

Peni-parallel venation

Is a type of venation where the veins are attached to both sides of the midrib in a parallel direction like barbs or feathers. Is found in Musa sp.

Palmate venation

Is a type of venation where the veins arise from a common point and radiate in a fan shape position from the tip.

Obsolete venation

Is a type of venation observed in succulents, where the veins are no longer evident.

Stipules

Two flaps of tissue that originate from the petiole. Present in many eudicots.

Minor veins

Veins that branch out from lateral veins. Is present in eudicot leaves.

Petiolule

Where a leaflet attaches to the primary rachis in a compound leaf.

Primary rachis

An extension of the petiole in a compound leaf.

Unipinnate

A type of compound leaf where the leaflets arise from the primary rachis. Can either be odd or even pinnate.

Bipinnate

A type of compound leaf where the primary rachis branch out once into secondary rachis and the leaflets arise from there.

Tripinnate

A type of compound leaf where the primary rachis branch out into secondary rachis and tertiary rachis. The leaflets appear on the tertiary rachis.

Palmately compound leaf

A type of compound leaf where all leaflets arise from one common point. Leaflets superficially appear as articulated fingers.

Unifolioliate

A type of palmately compound leaf with only a single leaflet. Their two lateral leaflets are suppressed and only the central leaflet is functional.

Bifoliloliate

A type of palmately compound leaf with a double leaflet.

Trifolioliate

A type of palmately compound leaf with triple leaflets.

Quadrufolioliate

A type of palmately compound leaf with four leaflets.

Pentafolioliate

A type of palmately compound leaf with five leaflets.

Multifolioliate

A type of palmately compound leaf with more than five leaflets.

Dorsi-ventral leaf

A type of leaf where the adaxial surface has a waxy layer and the dorsal surface gas guard cells and stomata present.

Stomata

Are tiny openings or pores in the plant tissue that allow for gas exchange. Mostly found in the lower section of eudicot leaves.

Guard cells

Pairs of epidermal cells that control gas diffusion by regulating the opening and closure of stomatal pores.

Palisade mesophyll

A type of mesophyll composed of tall cells vertically oriented to the leaf surface.

Spongy mesophyll

A type of mesophyll composed of irregular parenchyma with a lot of intercellular spaces.

Stomatal crypts

Areas where the epidermis is depressed. Is where stomata can be found.

Cuticle

A waxy outer layer found above the epidermis.

Leaf gap

The parenchymatous regions located beside the leaf trace.

Leaf trace

A strand of conducting vessels extending from the stem to the base of a leaf.

Isobilateral leaf

A type of leaf where the distinction between upper and lower surfaces are absent. The mesophyll is also usually indistinguishable.

Amphistomatic

Is when stomata is present on both sides of the leaf.

Bulliform cells

Are large, bubble-shaped epidermal cells that occur in groups on the upper surface of the leaves of many monocots.

Tendrils

Threadlike structures that coil on a surface and support the plant. Is a specialized leaf.

Phyllodes

When the petiole and part of the rachis flatten unti a sickle shaped structure for food manufacturing. Present in Acacia.

Bracts

Brightly colored specialized leaves that serve as insect attraction. Found in Bougainvillea.

Xeromorphic leaves

Leaves found in plants adapted for dry habitats. Small, compact, abundant sclerenchyma, abundant trichomes.

Phyllodic leaves

Expanded petuoles that function for photosynthesis much like leaf blades. Found in acacia.

Hydromorphic leaves

Leaves of plants found it water. Petioles and blades have air spaces and air ducts to store air for oxygen availability and buoyancy.

Insectivorous leaves

Leaves used in catching insects for additional plant nourishment.

Glandular trichomes

Covers the surface of the Drosera leaf. Secretes sticky digestive fluid.