Light Seed - A seed which will not greminate unless it gets exposed to light.

Light Stage - The stage in photosynthesis when triosephosphate has been formed from a 3-carbon acid (Phosphoroglyuceric acid). The energy absorbed by the chloroplasts splits the water molecule into hydrogen and oxygen.

Lignicole, Lignicolous - Growing on, or in wood, or on trees.

Lignification - The deposition of lignin on and in a cell-wall.

Lignin - A complex carbohydrate which is deposited in the cellulose micella of the cell-walls of woody tissue.

Lignocellulose - A compound of lignin and cellulose occurring in the wood and other fibrous materials.

Ligule - (1) A flattened membrane which arises from the base of the leaves of some lycopods.
(2) A membrane at the junction of the leaf-shealth and leaf base of many grasses.

Limiting - Describing addition of lime to a soil to overcome the soil acidity and improve soil structure or to compensate for calcium deficiency in soil. Quicklimes, slaked line, ground chalk or limestone are used for liming.

Limiting Factor. A factor which stops or reduces the speed of a reaction, when all other factors are present in abundance.

Limit of Trees - The line, north or south, or upwards on mountains, beyond which trees do not naturally occur.

Limnology - The science dealing with the study of inland aquatic ecosytems.

Linear - Said of leaves that are elongated, much less in breadth and with parallel sides for most of their length e.g., in grasses.

Linkage - When two genes become relatively close together on a chromosome, as not to get separated during crossing-over in meiosis, i.e., they are inherited together, and are said to be linked.

Linkage Group - A group of herediatary characteristics which are associated with one another through a number generations.

Linkage Map - A chromosome map which is determined by recombination relations.

Linnaean (Linnean) Classification - Said of the system of classification and binomial nomenclature established by Linnaeus.

Linnaean Species - A wide conception of a species, in which many varieties have been included.

Lip - A large projecting lobe of a corolla.

Lipase - An enzyme which breaks down a true fat into its component fatty acid and glycerol.

Lipid (Lipide). An ester which is formed from an alcohol and one or more fatty acids.

Lipopolysaccharide - Any molecule having both lipid and carbohydrate elements; found in cell wall of gram negative bacteria.

Lipo-Protein - Compounds of protein and a fat, which occur most commonly in membranes.

Liposome - A fatty or oily globule in the cytoplasm.

Lithocyst - Said of a cell that contains a cystolith.

Lithophyte - A plant which is growing on rocks and stones.

Lithosere - The type of xerosere developed on rock outcrops or rocky substratum in which pioneer community usually consists of lichens.

Liverworts - Used for bryophytes which belong to class Hepaticae I having thallose and leafy liverworts totalling about 1,050 : species of 295 genera. Plants are non-vascular, markedly I dorsiventral, gametophytes which produce antheridia and archegonia on thallus surface or on fleshy stalks.

Living Fossil - Any present-day species resembling in some characteristics to extinct organisms only. Such species usually occur in relatively unchanging environments and have evolved very slowly. Related species of such organisms occur in abundance in fossil records. For example, living fossils discovered in China are Ginkgo biloba and Metasequoia glyptosstroboidcs.Said of the soil which have even proportions of sand, silt and clay. It possesses best water holding capacity, soil structure and nutrient availability making it the best soil for cultivation.

Lobe - (1) One of the parts into which a flattened plant member is cut, when the parts are two large and distinct to be called teeth, but not wholly separate from one another.
(2) A portion of a divided (not compound) stigma.

Locule (loculus) - Used for describing a cavity insome part of the body of an organism within which specialized structures may develop.

Loculicidal - Said of the dry dehiscent fruit capsule in which wall bursts in the middle of locules and placenta also splits alongwith e.g., cotton.

Locus - (1) The position of a particular gene on its chromosome.
(2) Hilum of starch grains.

Lodicule - A scale below the ovary of a grass flower with represents the reduced
perianth. There are usually 1 or 2 (rarely) and they get distended with water and
assist in the separation of the glumes.

Loess - A wind-dispersed soil.

Logarithmic Phase - Said of the period during which populution growth when number of organisms is increasing at an ever increasing rate of population, increases.

Lomosome - Used for describing a complex invagination of the plasma membrane into the cytoplasm. It occurs in some fungal hyphae and spore-producing structures, algal cells and in some cells of higher plants.

Lomentum - Said of a type of dry, schizocarpic fruit which is actually a modification of legume and is developing from monocarpellary superior ovary that has one or more seeds. On maturity, fruit has been divided by development of false / septa into many one seeded units at: valves that fracture into as many mericarps during dehiscence e.g., groundnut

Long-day Plant - A plant that needs more than 12 hours of daylight, followed successively by shorter periods of darkness before it will flower.

Loose Smuts - Said of plant diseases in which spores of casualting fungus produce characteristic uncovered, black, powdery mass of spores on the host e.g., loose smut of wheat by Ustilago nuda.

Lophortrichous - Said of a bacterium in which a group of flagella is present at one end of the bacterial cell.

Lotic - A freshwater ecosystem in which water flow is continuous e.g., a river.

Lumen - A cavity enclosed by a cell wall such as the central space of xylem vessel.

Luminescence - See bioluminescence.

Lyases - Enzymes which break-down complex molecules to simpler ones, without hydrolysis, e.g., carbonic anhydrase breaks down carbonic acid to water and carbon dioxide, H2 C03 - H2O + CO2.

Lysigenic, Lysigenetic, Lysigenous - Said of a space which is formed by the disintegration of cells, especially of secretory cells leaving a cavity containing the secretion.

Lysis - The bursting of a bacterial cell when attacked by a bacteriophage.

Lysogenic Phage - A bacteriophage which does not kill its host.

Lysogeny - Said of breakdown of a bacterial cell infection of a bacteriophage. All RNA viruses and some DNA phages tend to induce lysogeny.

Lysosome - Said of an organelle which is bounded by a single membrane and having hydrolytic enzymes that can degrade cellular components.

Lysozyme - A substance, present in some plants, which has the capacity to kill bacteria. It resembles an enzyme in some respects, but cannot reproduce itself.

Lytic Cycle - Said of the sequence of processes and events taking part in lysogeny. It involves absorption of a phage to a specific on the bacterial wall, followed by penetration and entry of phage into the bacterium, then transcription and translation of phage genetic material within the bacterium and finally lysis of bacterial cell for releasing the newly formed phages.

Lytic 'Phages' - A bacteriophage causing lysis.