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Dictionary of Landscape Architecture and Construction

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leaf mold Decaying leaves often used as an amendment to soil.

leaf rake A long-handled tool with a fan-like piece attached for dragging leaves or such into piles. The fan shape is usually made of thin, flat, stiff, and bendable bamboo, metal, or plastic strips.

leaf rollers A moth (lepidopteran) having larvae that damage plants by rolling in a leaf to make a nest. It prefers oak or fruit trees. They have a number of insects that usually hunt them and keep populations down, but when found, remove the leaf and destroy it. If infestations are heavy, chemical sprays can effectively control them.

leaf scar The mark left on a branch, stem, twig, etc. when a petiole becomes detached and the leaf falls. It is very noticeable on some plants.

leaf scorch The partial or complete desiccation of a leaf due to lack of water supply to the leaf. This may be caused by lack of irrigation, frozen roots, damage to roots, drying winds, etc. Precautions can be taken by planting shade-loving plants in shade, using drought-tolerant plants in areas of heat or low irrigation, watering plants adequately, adding mulch around plants to prevent evaporation, and by controlling insects and diseases.

leaf skeletonizer Any caterpillar that eats the fleshy portion of leaves so that a skeleton-like leaf is left.

leaf spot See anthracnose.

leaf tiers A term given to caterpillars that feed on leaves and tie them together with silky threads.

lean concrete Any concrete with low cement content.


ledger In framing, a horizontal element of lumber supported by a post, wall, etc. and having joists attached to it.

ledger board A horizontal board joined by vertical supports, as in fence construction.

ledger strip A strip of wood nailed along the bottom of a beam to assist in supporting joists.

leggy Plants with stems unnaturally long from lack of light, high temperatures, excessive nitrogen, etc. Their lower areas usually have few leaves.

legume A family of plants with roots that contain nitrogen-fixing bacteria (e.g., rhizobium). This family includes some herbs, shrubs, and trees. Important food and forage plants belonging to this family include clovers, beans, and peas.

leguminous Pertaining to legumes.

lemma In a grass flower spikelet, the lower of two bracts enclosing the flower. It has its back at the outside of the spikelet.


lens Glass or plastic enclosing the bulb of a luminaire, allowing light to be transmitted through it.

lentic Having to do with wetlands, ponds, or lakes that are not flowing waters.



lenticel A group of loose corky cells formed beneath the epidermis of woody plants, rupturing the epidermis, and admitting gases to and from the inner tissues and atmosphere. They appear as many regularly spaced, slightly raised spots or elongated bumps on the woody portions (especially smooth bark) of some plants. Betula nigra is an example of a plant with visually pronounced lenticels on its bark.


lenticular In botanical terms, lens-shaped, both sides convex.

lepidote A botanical term that means scaly or covered with small scales.

LESA Abbreviation for Land Evaluation Site Assessment or Agreement.

letter of intent A letter indicating one will enter into a contract with another.

levee 1. A mound of sediment along a riverbank deposited as a result of periodic flooding. 2. A dike to contain the waters of flood irrigation. 3. A spot on a river for landing boats. 4. Any man-made embankment constructed

to prevent flooding. They are most often made of earth and are meant to contain, control, or divert the flow or rising of water or protect property and lives.

level 1. Any instrument used to measure whether a surface is horizontal, level (perpendicular to a line pointed to the center of the earth), or sloped. They are of two types: handheld and mounted. A handheld level is a surveying instrument usually comprised of a telescope with a bubble. A mounted level is a surveying instrument usually comprised of a telescope with a bubble used to level it on a tripod support, on which it rotates in shooting elevations and determining slopes, etc. 2. A spirit level. 3. The position of a line or plane when perfectly horizontal (perpendicular to a line drawn to the earth’s center).

leveling 1. In landscape work, making the ground evenly smooth (almost always with some slope for drainage), usually in preparation for planting, irrigation work, placement of mulch, etc. 2. The act of moving or securing an object or structure to a position as described under level (3).

leveling rod or leveling staff A rod with measurements marked upon it for measuring differences in grade elevation.

l.f. Abbreviation for lineal feet.

LFT Abbreviation for linear foot.

lg. 1. Abbreviation for long. 2. Abbreviation for length. 3. Abbreviation for large.

lgth In the lumber industry, abbreviation for length.

LH Abbreviation for left hand.

liability insurance Insurance that protects the insured against physical or financial injury to the person or property of someone else.


liana A botanical term referring to a climbing or woody vine.

license A written permission given to engage in an activity, as required by law or agency rule.

lien See mechanic’s lien.

life-cycle cost The cost of a material, or piece of equipment, structure, etc., including its initial cost and maintenance costs during its lifetime.

lift 1. A layer of compacted fill material. This earthen material is used in filling operations placed at various thicknesses to facilitate some end such as a degree of compaction. A compacted, stable fill is comprised of lifts of a certain thickness (as necessary for various materials and aggregates to facilitate compaction) that have each been compacted. 2. A scaffold frame above another scaffold frame. 3. Concrete poured between two construction joints. 4. A portion of vertically formed concrete poured at one time. 5. An amount of grout or mortar placed at one time in a structure such as a wall. 6. A bench in a multilevel excavation. 7. A forklift.

liftgate A gate opening by moving it vertically, as opposed to a gate that swings open on a side edge.

lifting Digging plants up for storage or for transplanting.

lift latch or thumb latch A bar on a door (small or large) that must be lifted at one or both ends to allow the door to open.

light 1. A pane of glass. 2. An artificial source of illumination.

light pole

lightbulb See incandescent lamp.

light globe Most often this refers to an incandescent lamp.

lighting 1. Various methods, equipment, etc. used to provide light; illumination. 2. The coverage, distribution, and intensity of any artificial light. 3. Any devices supplying artificial light.

lighting fixture An electrical device that holds a lamp, usually has a lens, and often is decorative.

lighting panel An electrical box containing fuses or circuit breakers protecting branch circuits serving lighting fixtures.

lighting unit A lighting fixture. Also a luminaire.

lightning arrester A device protecting electrical wiring and devices from the affects of lighting.

light pole Any pole holding aloft a light source. They are usually made of metal or wood and contain a hollow portion where wires or pipes can be concealed.

light source

light pole


light shade

light shade Filtered shade or shade during part of the day.

light soil A term used loosely without specific definition to describe soils that are easily worked and not compacted, are mostly sandy (having little clay), full of lightweight organic matter, or made up of large particles. This term does not refer to its color or weight.

ligneous Wood, wood-like, or resembling wood.

lignification The process of making something woody. This takes place by the depositing of lignin.

lignin The woody cell walls of plants and the material between them that bonds them. The woody portion of plants.

ligulate In botanical terms, furnished with a ligule.

ligule A botanical term literally meaning a little tongue. It is often applied when describing the flattened part of the ray corolla in Asteraceae and to the appendage on the inner (upper) side of a leaf at the junction of the blade and sheath in many Poaceae and some Cyperaceae (grass-like plants).

limb 1. A large branch of a tree. 2. The expanded part of a sympetalous corolla above the throat. The expanded portion of any petal or leaf.

lime 1. With regard to soils, CaO, calcium carbonate, or its application. It comes in several forms from limestone-derived materials and is beneficial for increasing pH (neutralizing acidic soils), for making clay soil more granular (less sticky) and porous, for assisting sandy soils in retaining water and becoming more compact, as well as for improving soil nutrient availability. In acid soils, it will assist in breaking down humus and making available more phosphorus

and potash otherwise not available to plants (unless applied too heavily). 2. A fruit of Citrus aurantifolia.

lime concrete Concrete made from mixing lime, sand, and gravel.

limestone A sedimentary rock of calcite or dolomite useful as building stone or crushedstone aggregate.

limit of disturbance One or more specified areas on a lot or parcel within which all disturbance of land such as construction of structures, driveways, parking, roads, landscaping, water surfaces, decks, utilities, walks, or improved recreation facilities are to be located. Some agencies omit areas restored with natural vegetation from being part of the limits of disturbance.

limnetic The portion of a wetland void of emergent vegetation because of deep water. Here light does not penetrate to the bottom of the water.

lineament 1. Straight features in the landscape, usually in reference to revealing some feature of the subsurface such as a geologic change or fault. 2. A distinguishing or characteristic feature of the land.

linear In botanical terms, a leaf that is narrow and flat with the margins parallel.


linear pit A trench large enough for planting trees together in a linear alignment along a street, walk, promenade, etc. where they will share rooting space. It is useful to provide extra rooting space and stability for the tree structure where the space would otherwise be limited by


urban features (walls, foundations, curbs, pavement, etc.) or other materials unfavorable to rooting.

line level A small spirit level (bubble level) enclosed in a metal or plastic case with hooks that can be hung on a string. When the string is pulled tight the bubble indicates proximity to level by its proximity to being centered. This is useful in determining grades for drainage, checking bottoms of excavations, the slope of a pipe or ditches, or in construction or placement of objects and structures, etc.

line of sight or line of collimation 1. A line seen through a surveying instrument when looking toward an object or point. 2. A direction of observation by one looking at an object, especially in the landscape. 3. A visual path from a particular vantage point.

liner A small, propagated, immature plant usually made available by nurseries, to grow in containers to a larger size more suitable for sale. They are often grown in flats or trays with small planting soil cups.

lintel A horizontal member above an opening that usually carries weight of materials and loads above it.

lip In plant identification and descriptions, a projection or expansion of a plant part.

liquefaction The change that comes about in some granular material (earthen material) from a solid state to a liquid state in an earthquake due to vibrations and shaking.

liquidated damages Any amount specified to be paid by a contractor to an owner as compensation if a contracted work should extend its completion beyond the date agreed upon at the time of signing the contract for the work.

liquid fertilizer Plant nutrients applied in a water solution.

littoral transport

liquid limit A term used in reference to a soil condition where, with any more water added to the soil, the soil would change from a plastic to a liquid.

liquid manure A liquid fertilizer made by soaking manure in water and then removing the solid portions.

liter (l) The metric measurement of 1 l, 61.02 c.i., 0.908 dry quarts, or 1.057 liquid quarts.

litmus An organic chemical strip of paper useful for indicating acidity or alkalinity. It becomes red when placed in something having pH values below 4.5 and blue for pH values above 8.3.

litmus strip See litmus.

litmus test A procedure, situation, or experiment that reveals information or truth. See also litmus.

litoral See littoral.

litter Waste materials such as bottles, glass, cans, scrap metal, plastic, garden rubbish, junk, paper, disposable packages or containers, and all other similar materials, and any other substance that is a nuisance to the public, or that creates a public health, fire, or safety hazard.

litter layer The Oi layer within the O horizon of a soil profile. It is comprised of undecomposed and recognizable organic matter such as leaves, sticks, and other living organism residue. If it is present, it is the surface layer.

littoral, litoral 1. The shoreward zone of a lake or wetland. 2. The area where water is shallow enough in a lake or wetland to allow emergent vegetation. 3. Growing on or near a shore. 4. The zone on a shore between high and low water marks.

littoral transport Movement of sediment along a coastline.


live load

live load 1. Any load on a structure that is not permanently existing as a force on the structure. 2. The weight load expected or existing on a structure, including people, furniture, equipment, and appliances. It does not include the influence of wind, earthquake, etc. 3. Any and all loads imposed on a building, deck, bridge, or other structure due to use or occupancy.

live stake A live, woody, long-stem portion of a plant, usually without any branches, roots, or leaves still attached, pounded, or placed into the ground as a planting procedure. If suitable plant material is used, and they are prepared and placed correctly, they will root and leaf out. In the illustrations, two types of stakes are shown. One is pounded into the ground. The others are of small diameter and are planted by punching a hole with a prong on a tractor or by excavating and backfilling.

living unit A dwelling providing living facilities for one family including provisions for living, sleeping, eating, cooking, and bathroom facilities.

load 1. A force (especially by weight) or system of forces, applied to a structure, a structural member or foundation, etc. of a structure. 2. The power delivered to an electrical device or piece of equipment.

loader A motorized machine of various sizes having a front bucket and arms for scooping earth or materials, lifting them, transporting them on wheels or tracks, and dumping.

loading dock A raised area (dock) that a truck or train can be backed up to being about the same elevation as the vehicle or trailer bed elevation to be unloaded. This allows for easier unloading or loading.

loam The textural class name for soil having a moderate (or relatively even) amount of sand, silt, and clay. It is comprised of 7 to 27% clay, 28 to 50% silt, and 23 to 52% sand. This is the ideal soil for most plants, and the term loam is used to describe soil rich in organic matter, not easily compacted, and able to drain well. It is mellow with a slight gritty feel but fairly smooth and a little plastic-like. When it is squeezed while dry, it forms a cast that will not break with careful handling, but when squeezed while moist can be fairly readily handled without breaking.

loamy sand A soil textural class comprised of 0 to 15% clay, 15 to 30% silt, and 70 to 90% sand.

lobe In botanical terms, any projection or division by indentation (especially a rounded one)

living unit

lm Abbreviation for lumen.; abbreviation for lineal meters.

lm/sf Abbreviation for lumen per square foot.

lm/W Abbreviation for lumen per watt.



lobed leaf margin

of a leaf, etc., especially when not extending more than halfway to the midvein or base.

lobed In botanical terms, a plant part, especially a leaf, with cuts or indentations usually less than halfway to its base or midrib. (Compare with ciliate, pectinate, cleft, entire, dentate, denticulate, serrate, serrulate, double serrate, incised, crenate, crenulate, parted.)

lobed leaf margin

locknut 1. A nut with a design (various types) that creates friction against the bolt it is fitted to, or against the surface it is tightened to, causing resistance to rotation and loosening. These types of nuts are made so as to not loosen without extra force when they are tightened. 2. A

longitudinal section

nut used against another nut to tighten and hold fast each nut and prevent loosening.

lock washer A washer with various designs for binding against a bolt head and the surface it is forced against, causing resistance to removing the bolt by rotating.

locule A compound ovary of a plant.

locust Coarse-grained, strong wood of a locust tree. It is hard, decay-resistant, and durable; often used for posts.

lodicule One of the tiny scales in the inflorescence of grasses.

loess A wind-deposited accumulation of uniformly sized, silty material, or any silt deposits usually of a buff or yellowish brown color thought to have been accumulated by wind.

logo A stylistic design, emblem, or representation used for identifying or representing an object, firm, development, etc. Many developments have logos designed by landscape architects. It may or may not contain words, letters, or numbers.


longitudinal section A drawing of a subject as if viewed from a plane that intersects the object lengthwise.



long-radius or sweep radius or sweep elbow

A term for a bent pipe portion or fitting changing a pipe’s direction with a large sweeping radius assisting in avoiding pressure loss to resistance, improving flow characteristics, or facilitating easier pulling of wire through it.

longshore transport Movement of sediment parallel to the coastline.

long ton The weight of 2240 lb (1016 kg).

looper See inchworm.

loose cubic meter Material not in a compacted state and measuring one cubic meter in volume. Usually refers to soil as it has a significant difference in volume between its loose and compacted states (difference in volume depends on type of soil with variations according to presence of sand, rock, organics, etc.).

loose material Soil or rock in a blasted, broken, friable, or loadable state.

lopper A long-handled pruner with jaws that either bypass each other or cut against an anvil jaw.

lost-head nail A nail with a small head intended to be pounded beneath a surface and lost to view.

lot A contiguous parcel of land used or set aside for use as the site of one or more buildings or other definite purpose.

lot coverage Usually refers to a measure of intensity of land development by examining the land area of a site that is impervious.

lot frontage That part of a lot contiguous (in control) with a street, easement, etc.

lot line The defined property boundary on the land.

louver An assembly of sloping, overlapping blades or slats often used in overhead structures outdoors to allow some sun to reach a surface

below and prevent some (or all sun at a particular time of day) from reaching that surface. They are also used in fences to allow light and air while providing some screening. See also abat-vent.

low bid In analyzing a number of bids submitted, this is the one that proposes to perform the required work or provide the materials at the lowest price compared to the other bids.

low-carbon steel Steel comprised of less than 0.20% carbon.

low-density concrete Concrete with an oven-dry weight of less than 50 pounds per cubic foot (800 kg/m3).

lowest responsible bidder or lowest responsive bid or lowest qualified bidder

The bidder with the lowest price that meets all requirements of the bid, which may include licensing, bonding, experience, proper forms, correctly filling out forms, and so on.

low-flow irrigation See micro-irrigation.

low hazard According to the National Standard Plumbing Code, a situation in which a backflow of water in a system would be a nuisance or objectionable, but not a health hazard.

low-head drainage The drainage flow of water left over in pipe and equipment through a low elevation sprinkler head (or heads) after a valve is turned off.

low-pressure mercury lamp A mercuryvapor lamp that obtains no more than 0.001 atmosphere during operation.

low-voltage lighting This is usually an outdoor lighting system with luminairies that operate on low voltage converted from single phase (120 volts) or sometimes supplied by solar photovoltaic collectors with batteries for storage.

low-voltage wire In irrigation systems using solenoids on valves, operated by low-voltage


electricity (24 volts drawing 2.3 to 10 amps), the wire associated with such a system is referred to as low-voltage wire.

LPS Abbreviation for low-pressure sodium.

L.S. Abbreviation for lump sum.

LT, lt On drawings, abbreviation for light.

LULU Abbreviation for locally unwanted land use. This phrase is often used with regard to proposed development projects heavily opposed by local residents.

lumber Parts of logs (woody portions of trees); any wood that is split or sawed. It is prepared for use in construction, building, etc., and is usually thought of as smaller than timbers and larger than wood pieces.

lumen A unit of luminous flux. One footcandle is a measure of one lumen per square foot on a surface.


luminaire A complete light fixture for attachment to electrical wiring including the bulb or tube for production of light, any reflectors, housings, and any decorative embellishments.

luminance The luminous intensity of a surface.

luminosity The ration of light expressed in lumens per watt.

lump-sum agreement A contract to complete work for a set amount agreed upon before the work begins.

lunate In botanical descriptions, crescentshaped.

lustrous In botanical descriptions, shiny or shining.

L.V. Abbreviation for low voltage.

lyrate In botanical terms, lyre-shaped. It can be an obovate or spatulate pinnatifid leaf with the end lobe large and roundish and the lower lobes small.


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