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On-Line Glossary: L

Each entry consists of a term (in bold), a definition of the term, and a number in parentheses (0) indicating the source of the definition. Clicking on the speaker icon will give you the pronunciation of the term. (Be sure to close the window for the sound player after each use.) The pencil icon will give you a drawing, and the camera icon will give you a photograph.


labial. In nematodes: Pertaining to the lips. (14)

lamella. See gill. (Pl. lamellae.)

lateral field. In nematodes: An interruption of the transverse striae by longitudinal cuticular thickenings situated on top of the lateral chords. The field is divided by longitudinal striae (incisures) and at times by transverse markings (areolation). (14)

latent infection. 1. Infection unaccompanied by visible symptoms. 2. See latent period. (21)

latent period. 1. The period between infection and the appearance of new inoculum. (See incubation period.) 2. Elapsed time between phage infection or induction and lysis of bacterial cells. 3. Period after acquisition of virus by a vector before it becomes infective. (8, 24)

latent virus. A virus that infects a plant without causing macroscopic symptoms. (8)

lateral organs. See amphid.

leaf spot. A self-limiting lesion on a leaf. (2)

lectin. A plant protein that binds to certain sugar residues in glycoproteins. (10)

lectotype. One of a series of syntypes that, after publication of the original description, is selected and designated through publication to serve as the type. (14)

legitimate. Of taxonomic names and epithets: Published in accordance with the Code of Nomenclature. (22)

leptoderan. In nematodes: Caudal alae that do not meet posterior to the tail tip. (14)

lesion. A localized area of diseased or damaged tissue. (3)

library. In molecular biology: A set of cloned fragments together representing the entire genome. (13)

lichen. A thallus consisting of an alga and fungus intermixed and living in a symbiotic relationship. (15)

life cycle. The complete succession of changes undergone by an organism during its life. A new cycle occurs when an identical succession of changes is initiated. (20)

line. See incisure.

lips. In nematodes: Cuticular structures (usually six: two subdorsal, two lateral, two subventral) surrounding the mouth opening; lips may be fused in pairs. (14)

local infection. An infection affecting a limited part of a plant. (20)

local lesion. A localized spot produced on a leaf upon mechanical inoculation with a virus. (2)

locular. Containing chambers or hollows. (17)

locule. A cavity. (17)

loculoascomycete. A member of the Loculoascomycetes.

Loculoascomycetes. A group of Ascomycotina with bitunicately discharging asci, producing ascospores that are generally septate and borne in unwalled locules (pseudothecia) in ascostromatic ascomata with an ascolocular ontogeny. Not accepted by some authors. (7)

locus. Site on a chromosome occupied by a particular gene.

lumen. In nematodes: Triradiate canal or duct of the esophagus. (14) In fungi: The space bounded by tissue or wall, as the central cavity of a cell. (17)

lunate. Crescent-shaped; half-moon shaped. (17)

luteovirus. (Literally "yellowish".) Member of a group of plant viruses with isometric particles containing one molecule of linear RNA, mainly confined to the phloem, and usually not mechanically transmitted but transmitted in nature by aphids in a circulative manner. (5)

lyophilization. Rapid freezing of a material at low temperature followed by rapid dehydration by sublimation in a high vacuum. A method used to preserve biological specimens or to concentrate macromolecules with little or no loss of activity. (Also freeze-drying.) (10)

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