Lateral Conjugation - Describing a form of conjugation in certain filamentous algae, particularly of Zygnematales, in which there occurs the formation of conjugation tube between two adjacent cells of the same filament.

Lateral Meristem - A meristem which is located at the side of a plant member.

Lateral Root - Any root arising endogenously from the pericycle of another root. but basically the two following conditions are necessary:
(1) In deep horizons, the parent rocks are permanently saturated with water, and have iron compounds which dissolve.
(2) In higher zones, where ferrous substances get oxidized as they are in contact with air. The top layer is usually brick hard, and of ferruginous material.

Latex - A milky fluid having sugars, proteins, alkaloids, oils, etc. It is produced in latex vessels of many plants.

Latex Cell - A simple or branched cell which is derived from the enlargement of a single cell, and contains latex.

Latex Duct - An elongated, branched, aseptate system of anastomosing hyphae, which contains latex, and is present in some of the larger agarics.

Latexosis - An abnormal secretion of latex due to a pathological condition.

Latex Vessel - Used for describing a simple, or branched tube, usually anastomosing with other similar tubes, derived from the nelargement and union of a chain of cells, and containing latex.

Laticifer - A cell or linked system of cells having latex and penetrating into various tissues in certain plants, Laticifer of a single cell is known as simple, of joined complex of cells is known as compound laticifer.

Latin Square - An experimental design in which the number of treatments is equal to the number of replications and each treatment is taking place only once in every row and column.

Latosol - A soil which is formed by laterization having a leterite.

Layer - A stratum of vegetation, as the shrubs in a wood.

Layering - (1) The banding which is seen in thick cells-walls, due to the presence of wall-layers differing in water-content, chemical composition, and physical structure.
(2) The grouping of vegetation in a wood into 2 or more well defined layers differing in height, as trees, shrubs, and ground vegetation.
(3) A method of artificial propagation in which stems pegged down until they root, and then detached from the parent plant.

Leaching - Used for the removal of mineral salts from the soil by percolating water.

Leader - One of the main shoots of a tree.

Leaf - Used for describing an outgrowth from the stem of a vascular plant. It is usually green and mainly concerned with photosynthesis, and transpiration. It consists of a leat base, petiole, and flattlened lamina, which is usually conspicuously veined.

Leaf Area Index, (LAl) - Defined as the ratio of total surface of a plant's leaves to the ground area that is available to that plant i.e. LAI=leaf area/basal coverage of plant.

Leaf Area Ratio - Describing the value which is derived by dividing the total surface area of all the leaves of a plant by its total dry weight.

Leaf Buttress - A lateral prominence on the apex of shoot which is finally differentiated into a leaf.

Leaf Canopy - Used for the total foliar coverage of a plant. This term usually refers to the umbrella of foliage in a large tree.

Leaf Culture - Describing the culture of excised leaf, leaf material or leaf primordia on a sterile growth medium by fusing tissue culture techniques.

Leaf Curl - Used for a plant disease which shows curling and puckering of leaves in infected plant. It has occured due to an increase in cells on either side of midrib and extra growth of palisade and spongy mesophyll e.g., in peach and almond caused by fungus Taphrina deformans.

Leaf Fall - Used for describing the detachment and shedding of leaves from a plant due to formation of abscission zone at the base of petiole. Leaf fall is associated with fall in level of auxin in lamina.

Leaf Gap - (lacuna). Said of the parenchymatous area in the stele of many vascular plants which is associated with and positioned immediately above a leaf trace.

Leaflet - One separate portion of the lamina of a compound leaf.

Leaf Mosaic - Used for describing the arrangement of the leaves on a shoot or a plant in such a way that as much leaf as possible gets exposed to light, and as little as possible gets shaded by other leaves.

Leaf Primodium - Used for describing localized mass of meristematic tissue near the apical meristem. It ultimately divides to form a leaf.

Leaf Scar - The scar on a stem which is left after the leaf has fallen. It is commonly covered with a layer of cork.

Leaf Scar Periderm - A periderm which is developing across a leaf scar beneath the initial protective layer.

Leaf Shapes - The common leaf shapes are shown in Fig. 20.

Leaf Sheath - (1) An expansion of the petiole or leaf blade to surround the stem.
(2) Scale like leaves growing over the apical cell of a stem of the Equisetaceae.
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Leaf Spot - Describing a plant diseases which is characterized by limited areas of necrosis on leaves forming spots on it. It is caused by mineral imbalance, insects, weather conditions, viral, fungal or a particular phase of a disease that later gives rise to other more characteristic symptoms.