AgroForestryTree Database
Glossary S
sagittate (of leaves)
Shaped like an arrowhead; with two backward-directed barbs.
sago
Edible starch from the central pith of palm-like or palm trees, for example, Metroxylon sagu.
sal forest
A forest in which the dominant vegetation is Shorea robusta.
saline soil See also alkali soil
Soil containing high amounts of the sulphates and chlorides of sodium and calcium. Saline soils occur in hot climate, have a typically uneven surface, show little change down the profile and are low in humus. If the sodium salt is carbonate then the reaction can be around pH 9.0. Highly saline soils can contain as much as 1% of salts in the topsoil (that is, up to 250 t/ha in the top 120 cm).
salinity See also alkalinity
Concentration of dissolved salts in water (g/kg) when the organic matter has been oxidized, the carbonate converted into oxides, and the bromine and iodine converted into chlorine.
samara
A dry fruit that does not split open and has part of the fruit wall extended to form a flattened membrane or wing.
sand
1. Particles between 2.00 and 0.05 mm diameter, or one of several separates such as coarse or medium sand; a soil textural class.
2. Mineral or rock fragments that range in diameter from 2.00 to 0.02 mm in the international system, or 2.00 to 0.05 mm in the USDA system.
sap shoot
See coppice.
sapling See also pole, saw timber, seedling
1. Begins with the end of the seedling stage and ends when trees reach 10 cm diameter at breast height (dbh), the crowns are well elevated, and usually many of the lower branches have died.
2. A loose term for a young tree no longer a seedling but not yet a pole, that is, a few metres high and 2-3 cm in diameter at breast height (dbh), growing vigorously and without dead bark or more than an occasional dead branch.
3. A young tree, large enough to be above goat height, but still immature and not producing fruit.
saponins
A toxic, soap-like group of compounds which is present in many plants.
sapwood See also heartwood
The outer part of the wood of a trunk, in which the sap flows.
sarcotesta
In some fruits, a sheet of edible pulp in which one or more seeds are embedded.
savannah
A grassland with scattered trees, either as individuals or clumps. Often a transitional type between true grassland and forest. Sometimes spelled 'savanna'.
saw timber See also pole, roundwood, seedling
1. Trees of a size and quality suitable for sawing into timber.
2. Begins at end of the 'pole' stage when height growth falls off and the period of maximum diameter growth begins. Terminates when trees become overmature and die or are cut.
scale
A small, often membranous, reduced leaf frequently found covering buds and bulbs.
scaled
Covered by scale leaves.
scape
A leafless flower-stalk, for example, in the plantain.
scarification (of seeds) See also pretreatment
The abrasion of the seed coat (or fruit coat) by mechanical, chemical or physical (for example, dry heat) means. Usually needed to improve the germination of hard-seeded species.
scarious
Dry and membranous, with a dried-up appearance.
schizocarp
A fruit derived from a simple or compound ovary in which the locules separate at maturity to form single-seeded units.
scion
1. A twig, or portion of a twig, of one plant grafted onto the stock of another.
2. Any unrooted portion of a plant used for grafting or budding onto a rootstock. Shoots of woody plants from which scions are cut are called 'scionwood' or, if appropriate, 'budwood'.
scorpioid (of cymose inflorescences)
Curved to one side like a scorpion's tail.
scrab
A vegetation type intermediate between forest, bushland and thicket. It implies a poorly productive area.
scrambler
A plant with a spreading, creeping habit usually anchored with the help of hooks, thorns or tendrils.
seasonal plant See also annual plant
A plant that flowers and completes its life cycle within the duration of a single wet-dry season combination (in equatorial regions).
secondary forest species
See pioneers.
secondary succession
A succession initiated by an abiotic or biotic agent or agents after the ground has been cleared of its original vegetation.
sediment
Solid material, mineral or organic, in suspension in transport, or that has been removed from the original site by air, water, gravity, or similar agents.
seed
The unit of sexual reproduction developed from a fertilized ovule; an embryo closed in the testa which is derived from the integument(s).
seed orchard
A tree plantation established primarily for the production of seed of proven genetic
seed source
See origin, provenance.
seedling
The young plant arising from a germinated seed. The next stage of growth for a young tree is termed sapling. A plant grown as a seedling may retain its taproot, unlike one propagated from a cutting, and hence have a differently structured root system.
seedlot
1. A convenience term denoting a group of seeds, or their offspring, that will be considered as a unit in an experiment.
2. An indefinite quantity of seed having uniform quality produced at a specific location and collected from a single crop.
selective cutting See also mechanical thinning
A system of cutting in which single trees, usually the largest, or small groups of such trees, are removed.
selective herbicide
1. A herbicide that, if used appropriately, will result in control of some plant species without injury to others.
2. A herbicide that kills only certain groups of plants, for example, 2,4-D, which kills broadleaf plants but not grasses.
selective thinning See also mechanical thinning
Removing chosen trees, usually so as to give the maximum benefit to those remaining.
self
To place pollen from a male flower on a female flower on the same plant; a plant resulting from such pollination. Self-pollination, hence 'selfing'.
self-fertilization
See fertilization.
self-incompatibility See also pollinator
1. Inability to produce seed following self-pollination. Sometimes limited specifically to cases in which the inability is due to a pollen-borne gene that prevents pollen tube growth on a stigma having the same gene.
2. Genetically controlled physiological hindrance to self-fruitfulness.
self-incompatible
Of plants incapable of self-fertilization, usually because the pollen-tube cannot germinate or grows very slowly.
self-mulching soil
1. A soil with a high swelling potential in the surface layers so that it cracks into a granular mulch on drying.
2. A soil with a naturally formed, well-aggregated surface, which does not crust and seal under the impact of raindrops.
self-pollination
See self.
self-sterility
Inability to produce seed following self-pollination.
senescence
Deteriorative changes of an organ or whole plant preceding death (organ senescence, whole plant senescence). There can also be 'sequential senescence' (leaves along a branch) and 'synchronous senescence' (all at the same time).
senescent
The plant growth phase that encompasses full maturity to death.
sepal
A floral leaf or individual segment of the calyx of a flower, usually green.
septate (of ovaries)
Divided into locules by walls.
septum (pl. septa)
A cross-wall or partition.
septicidal (of fruits)
Splitting open longitudinally through the septa so that the carpels are separated.
seriate
Arranged in a row.
sericulture
The culture of silkworms (Bombyx mori) for the production of silk.
serrate (of margins)
Toothed, like a saw.
serrulate (of margins)
Finely toothed, like a saw.
service
In agroforestry, a beneficial attribute (apart from products) brought about by a particular practice, for example, shelter, soil fertility improvement, soil and water conservation.
sessile
Of a leaf, without a petiole (leaf stalk), borne directly on the stem.
shade-bearing tree
See climax species.
sheath (of leaves)
The base of a leaf or leaf-stalk (petiole) which encases the stem.
shelterbelt
An extended windbreak of living trees and shrubs established and maintained for the protection of farmlands over an area larger than a single farm.
shoot
The above-ground portions of a vascular plant, such as the stems and leaves; the part of a plant which develops from the plumule of the embryo.
short shoot
Where there is shoot dimorphism (2 kinds of shoots), these are often specialized shoots with greatly compressed internode, often bearing leaves and usually flowers; not contributing to the overall architecture of the tree. Sometimes called a 'spur'.
short-day plant
A plant whose development is affected by photoperiod, in particular where a process (for example, flowering) is promoted if the plant is subjected to day lengths below (night lengths above) a critical length.
shot-hole
Loss of dead areas inside spots that results in a series of holes in the leaf.
shrub
1. A woody plant that remains low and produces shoots or trunks from the base; not treelike nor with a single bole. A descriptive term not subject to strict definition.
2. A woody perennial plant differing from a perennial herb by its persistent and woody stem, and from a tree by its low stature and habit of branching from the base.
shrubland
An open or closed stand of shrubs up to about 2 m tall.
silicule, silicula
A dry fruit that opens along two lines and has a central persistent partition; it is as broad as, or broader, than it is long, as in the Cruciferae.
silique, siliqua
A silicule-type of fruit longer than it is broad, as in the Cruciferae.
silt
1. Particles between 0.05 and 0.002 mm diameter, or a soil textural class.
2. Mineral particles that range in diameter from 0.02 to 0.002 mm in the International System, or 0.05 to 0.002 mm in the USDA system.
silviculture
A branch of forestry concerned with the methods of raising and growing trees.
silvopastoral See also forest grazing
Any agroforestry system that includes trees or shrubs and pastures and animals.
silvopisciculture
Growing trees as part of a fish-farming enterprise.
simple (of leaves)
Not divided or lobed in any way.
simple bud See also compound bud
Bud containing either leaf or flower primordia but not both.
simple umbel (of inflorescences)
An umbel in which the stalks (pedicels) arise directly from the top of the main stalk.
sink root, sinker root
A root, other than a taproot, that grows straight downward in the soil.
sinuate (of margins)
Divided into wide irregular teeth or lobes which are separated by shallow
slash
In forestry, the vegetation (branch and other woody and leafy debris) left on the forest floor after trees have been felled or trimmed.
slash-and-burn system
1. A kind of shifting cultivation in high rainfall areas where the cropping period is followed by a fallow period during which grass, herb, bush or tree growth occurs.
2. A pattern of agriculture in which existing vegetation is cut, stacked and burned to provide space and nutrients for cropping; also called 'swidden' cultivation and shifting cultivation.
slashing
In forestry, cutting back the less tough, competing vegetation, for example, ground cover like bracken. A form of clearing.
small animal
An animal of relatively small stature (as compared, for example, with cattle and horses). Includes ruminants (for example, sheep and goats) and, strictly, also many others: antelopes, gazelles, porcupines, guinea pigs, rabbits, ostriches, poultry, iguanas, turtles, monitor lizards, honeybees, silkworms, worms. Trees and shrubs may play a part in any production enterprise concerning these.
sod
1. A surface layer of matted vegetation held together by the roots, rhizomes and stolons of grasses and other herbs.
2. A piece of turf lifted from a sward.
sod seeding
Sowing directly into a sward (grass or grass plus weeds) without prior cultivation.
softwood
A term used in the timber trade to describe the wood of most conifers (gymnosperms), as distinct from the hardwood, broad-leaved species (angiosperms).
softwood cutting
See cutting.
soil See also edaphic
1. The superficial part of the earth's crust resulting from weathering of rocks under the combined effect of living beings and climate.
2. A dynamic natural body composed of mineral and organic materials and living forms in which plants grow. The collection of natural bodies occupying parts of the earth's surface that support plants and that have properties caused by the integrated effect of climate and living matter acting upon parent material, as conditioned by relief, over periods of time.
soil aeration
The process by which air in the soil is replenished by air from the atmosphere. In a well-aerated soil, the soil air is similar in composition to the atmosphere above the soil. Poorly aerated soils contain more carbon dioxide and less oxygen. The degree of aeration depends on the soil porosity.
soil drainage
See drainage.
soil dry weight See also oven-dry soil
Weight of solid soil particles when all water has been vapourised after heating the particles to 105 deg. C.
soil fertility
The quality that enables a soil to provide adequate nutrients in a proper balance for specified plant growth, other factors such as light, moisture, temperature and the physical condition of the soil being favourable.
soil organic matter See also humus, organic matter
Material found in soil derived from living matter. 'Fibric' organic matter is the least decomposed and is mainly fibres; it has low bulk density and a fibre content >60% of the organic volume. 'Hemic' organic matter is intermediately decomposed; 'sapric' is the most decomposed, with the highest bulk density and the least fibre. Other ways of fractionating soil organic matter (such as into 'labile' and' and 'stable' fractions) are based on treatment with chemical agents, for example, different strength solutions of potassium permanganate.
soil permeability See also soil aeration
The quality of a soil enabling it to pass air or water.
soil porosity
The percentage of the soil (or rock) volume not occupied by solid particles, including all pore space filled with air and water. The total porosity includes both 'capillary' and 'non-capillary' porosity (capillary refers to the very small pores).
soil reaction See also pH
Degree of acidity or alkalinity.
soil structure
1. The combination or arrangement of primary soil particles into secondary particles, normally larger in size.
2. The combination and arrangement of primary soil particles, units or peds. The secondary units are classified on the basis of size, shape and degree if distinctness, such as 'crumbly', angular', 'platey', 'prismatic', 'columnar', 'blocky'.
soil texture See also clay, loam, sand, silt
The relative proportion of the various size groups of individual soil particles. 'Fine fraction' is silt and clay-sized particles <0.05 mm; 'course fraction' is the stone, gravel and sand >0.05 mm.
soil water content
The quantity of water in a soil to a stated depth. It can be expressed as a weight fraction (g/g) or a volume fraction (g/ml), so that volume fraction = weight fraction x bulk density.
solitary (of flowers)
Occurring singly in each axil.
spadix
A spike of flowers on a swollen, fleshy axis.
spathe
A large bract subtending and often ensheathing an inflorescence. Applied only in the monocotyledons.
spatulate, spathulate (of leaves)
Shaped like a spoon.
species See also subspecies
1. One or more populations, the individuals of which can interbreed but which, in nature, cannot exchange genes with members belonging to other species. A main category (taxon) or taxonomic classification.
2. A group of similar organisms capable of interbreeding and more or less distinctly different in geographic range or morphological characteristics from other species in the same genus.
specific gravity
As applied to wood, the ratio of the oven-dry weight of a sample to the weight of a volume of water equal to the volume of the sample at the same specific moisture content.
spicate
Spike-like.
spice garden
See mixed garden.
spike
An inflorescence of simple racemose type in which the flowers are stalkless (sessile).
spikelet
A small spike, as in the grasses.
spine
The hard and sharply-pointed tip of a branch or leaf, usually round in cross section.
spinose
Spiny.
sprout See also root sucker
A shoot from a dormant bud, often at the base of a tree, or from an exposed root or stump. A stump with one or more sprouts is called a stool.
spur
A short shoot.
stamen
The male reproductive organ of a flower. It consists of a usually bi-lobed anther borne on a stalk (filament).
staminate See also pistillate
Having stamens (male organs), but no carpels (female organs).
staminode
A sterile, often reduced or modified stamen.
stellate
Star-shaped.
stem
1. An organ displaying leaves and also conducting water with mineral salts and food. If the stem is herbaceous, it performs a photosynthetic function as well. The places where the leaves arise from the stem between 2 successive nodes are called internodes. The stem thus consists mainly of internodes (not present in roots) and bears leaves as well as buds.
2. An above-ground axis (usually) of a plant, which develops from the epicotyl (seedling stem tissue above the cotyledon) of the embryos, or from a bud of an already existing stem or root.
3. The principal axis of a plant, carrying all the accessory parts such as the branches, leaves and flowers.
stem pitting
A symptom of viral diseases characterized by depressions on the stem of the plant.
sterile
Of an organism, unable to produce reproductive structures, that is, unable to reproduce.
sterility
Inability to produce sound (viable) seeds.
stigma
The receptive part of the female reproductive organs on which the pollen grains germinate; the apical part of the carpel.
stipitate
Having a stalk or stipe.
stipulate
Having stipules.
stipule
A leafy appendage, often paired, and usually at the base of the leaf stalk.
stock See also grafting, rootstock
1. Part of a plant, usually consisting of the root system, together with a part of the stem, onto which is grafted a part of another plant.
2. The available material kept or gathered for planting.
stock plant. See also nursery stock
A plant kept to conserve a selected genotype, which can be multiplied by one form of vegetative propagation or another
stolon See also rhizome
1. A horizontal stem at or below ground surface that gives rise to a new plant at its tip. Less commonly, a shoot that bends to the ground and takes root.
2. An above-ground prostrate (lying on the surface) stem; may form roots at the nodes that come into contact with the ground.
stool
1. A living stump capable of producing sprouts. Also used to describe a living stump maintained in order to produce cuttings, layers, and so on; hence 'stool bed'.
2. A cut stump from which coppice shoots arise.
stratification
1. A pregermination treatment to break dormancy in seed and to promote rapid, uniform germination. The seeds are exposed to moisture at a temperature just above the freezing point (1-5 deg. C) for a specified time.
2. Arrangement of plants in layers, for example, a stratified canopy in a forest.
stubby root nematodes
Migratory ectoparasites; feed outside on the tips of feeder roots and cause them to stop growing.
stump See also propagate
1. Planting stock in which the shoot and root have been cut back (usually to some 2-3 cm for the shoot and 10-20 cm for the root) to produce an easily transported propagule.
2. The remaining, short part of a stem or branch that has been cut. Often refers to that part of a trunk left after a tree has been coppiced.
3. To clear an area of tree stumps by grubbing them out.
stump sprout
See sprout.
style
The elongated apical part of a carpel or ovary bearing the stigma at its tip.
subsoil
The B horizon of soils that weak profile development. Incorrect although common terminology, inherited from the days when soil was seen only as a ploughed layer, defines it as the soil below plough depth in which roots normally grow.
subspecies See also cultivar, variety
A geographically localized subdivision of a species, genetically and morphologically distinguishable from other subspecies, described according to taxonomic rules, and given a Latin name. A subspecies tends to be larger than a taxonomic variety but there is no clear distinction between the two.
succulent
With fleshy or juicy organs containing reserves of water.
sucker
1. A shoot arising from below ground level.
2. Lateral underground shoot that leaves the roots or rhizome and forms roots itself, making an independent individual plant.
suffrutescent (of herbaceous plants)
Having a persistent woody stem base.
suture
A line of union; the line along which dehiscence often takes place in fruits.
sward
1. A grassy surface of a lawn, pasture or playing field, not necessarily a pure stand.
2. A grassed area composed of short grasses giving a continuous cover, with no trees or shrubs present.
syllepsis See also prolepsis
Development of a lateral branch without a period of dormancy, that is, contemporaneous with its parent axis; hence sylleptic branch, a branch developed by syllepsis.
sylvopastoral
An agroforestry land-use system for the concurrent production of trees and animals that graze or browse or both.
symbionts
One of the partners in a symbiosis
symbiosis
A mutually beneficial relationship between 2 living organisms of different species living closely together. Fungus and algae that form a lichen, or nitrogen-fixing bacteria living in roots are examples of symbiosis. The individual organisms are called symbionts.
symbiotic
'Living together'. An association of 2 different organisms that live attached to each other, or one as a tenant of the other, and contribute to each other's support.
sympatric
Occurring in the place; inhabiting the same area. Having overlapping distributions.
sympetalous
With the petals united along their margins, at least at the base.
sympodial (of stems or rhizomes) See also cyme, monopodial
With the apparent main stem consisting of a series of usually short axillary branches.
syncarpous (of ovaries)
Made up of two or more fused carpels.
systemic See also contact herbicide, translocated herbicide
Found throughout the whole plant. As with soil- or leaf-applied herbicides or insecticides that are translocated to all other parts.
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