AgroForestryTree Database
Glossary M
See also microclimate
The climate character of a large region.
male flower
A flower containing functional stamens, but no carpels.
mangroves
1. Open or closed stands of trees and bushes occurring in the tropics in intertidal zones, usually around the mouths of rivers, creeks and lagoons where soils are heavy textured and have a fluctuating salt content and soil level.
2. A name used collectively for the assemblage of plants, as well as to refer to individual genera or species, for example, woody members of the Rhizophoraceae, Combretaceae and Verbenaceae. These have knee-like roots that are 'pheumatophores' (roots with air spaces). Grown for wood and tannins.
manure See also green manure
Animal excreta with or without a mixture of bedding or litter.
maquis
Area of Mediterranean scrubland, consisting of shrubs and isolated trees.
marcotting
See air-layering.
mast fruiting
A period of massive fruit production.
maturity
A phase in the development of a plant (usually irreversible) that marks the transition from juvenility, when the plant is unable to flower, to a full capacity to form flowers that are sexually reproductive (unless the plant shows apomixis).
mc
Moisture content (%).
mean annual increment
In forestry, for a particular stand, the total increment of wood up to a given stand age (in years) divided by that age. The mean annual increment for a whole rotation is termed the final mean annual increment.
mechanical thinning See also line thinning, selective thinning
Thinning in which a predetermined proportion of the trees is removed without regard to size or quality, such as, for example, every 3rd tree.
medium-term storage
The storage of seeds for medium-term periods as is often used for active collections in genebanks or by plant breeders and seedsmen. A period of 2-10 years is generally assumed.
membranous
Resembling a membrane; thin, dry and semi-transparent.
mericarp
A one-seeded portion of a fruit which splits up when the fruit is mature, for example, the fruits of the Umbelliferae.
meristem
1. A plant tissue composed of dividing cells and giving rise to organs such as leaves, flowers, xylem, phloem, roots.
2. A region of a plant in which cells are not fully differentiated and are capable of repeated mitotic divisions.
meristem culture
Apical meristem culture; a part taken (an explant) consisting only of the apical dome of tissue above the youngest leaf primordium.
mesocarp
The middle layer of the fruit wall (pericarp). It is usually fleshy, as in a berry.
mesophyte
A plant that requires a moderate amount of water for normal growth; includes most crop plants.
microclimate See also macroclimate
The atmospheric characteristics prevailing within a small space, usually in the layer near the ground that is affected by the ground surface. Special influences include the impact of vegetation cover on humidity (by evapotranspiration) and on temperature and winds.
microfauna
The small animals that can be seen only with a microscope, such as protozoa, nematodes.
microflora
The small plants that can be seen only with a microscope, such as algae, fungi.
microorganism
A member of the microflora or microfauna that can be seen only with a microscope.
micropropagation See also meristem culture
Various procedures by which small pieces of plant tissue are taken, surface sterilized and then grown on, or in, an appropriate medium under carefully controlled environmental conditions and provided with appropriate nutrients, growth hormones and supplementary components, to allow cells to differentiate into small plantlets (explants). These are then transplanted (perhaps several times) and eventually hardened off before being planted out.
midrib
The central or largest vein of a leaf or carpel.
mimosine
An alkaloid toxic to animals, which is contained in some members of the legume family (Mimosaceae) including Leucaena leucocephala. Its toxicity minimizes the amounts of leafy material that can be fed, although ruminants can detoxify mimosine through bacterial action in the rumen provided the rumen has the right microflora (either naturally or by inoculation).
mineral soil See organic soil
A soil containign less than 20% organic matter or having a surface organic layer less than 30 cm deep.
miombo
A form of woodland found in southern Africa in hot, semi-arid regions with a monomodal rainfall (for example, in Tanzania, Zimbabwe, Malawi and Zambia). Rainfall is high (>1 000 mm) and soils are poor in nutrients and acid. The vegetation is dominated by slow-growing, mainly deciduous, caesalpiniaceous trees (for example, Brachystegia julbernardia).
mixed cropping See also intercropping, multiple cropping
Growing more than one species on the same piece of land at the same time, or with only a short interval between.
mixed garden See also homegarden
A land-use form on private lands outside the village, dominated by planted perennial crops, mostly trees, under which annual (seasonal) crops are cultivated. When spices are grown they are called 'spice gardens'.
monocarpic
Fruiting only once and then dying.
monochasium
A cymose inflorescence in which there is a single terminal flower with below it a single branch bearing flower(s).
monocotyledon See also dicotyledon
One of two subclasses of angiosperms; a plant whose embryo has one cotyledon.
monoculture, monocropping
Growing a crop consisting of a single species.
monoecious See also dioecious
1. Bearing separate male and female flowers on the same plant.
2. Plants bearing unisexual flowers, both staminate and pistillate, on the same individual.
monogeneric (of a family)
Containing only one genus.
monopodial (of stems or rhizomes) See also sympodial
With branches or appendages arising from a simple main axis.
monotypic
A genus or a family containing a single species.
morphology
Science of form and structural shape.
mould
A profuse growth of fungus mycelium on dead plant tissue or any dead matter.
mucilage
A slimy secretion, which swells on contact with water.
mulch
1. A natural or artificially applied layer of plant residues or other materials such as stones, sand, paper or brush on the surface of the soil.
2. A covering of plant material put on the soil to improve its fertility, moisture retention capacity and organic content.
3. A loose surface horizon that forms naturally or may be produced by cultivation and consists of either inorganic or organic materials.
mulch tillage
Tillage or preparation of soil in such a way that plant residues are left on the surface.
multiple cropping See also intercropping, mixed cropping
Growing more than one crop on the same piece of land.
multiple-use forestry, multipurpose forestry
Any practice of forestry that fulfils 2 or more objectives of management, whether products, services or other benefits.
multipurpose tree, agroforestry tree
A woody perennial purposefully grown to provide more than one significant contribution to the production or service functions (for example, shelter, shade, land sustainability) of the land-use system that it occupies.
multiseriate (of flower parts)
Borne in many series or whorls.
multistorey system
An agroforestry system, such as a homegarden, that has a number of plant components of differing stature so that several layers of canopy are formed.
mycorrhiza
The symbiotic association of the roots of some seed plants with fungi.
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