Plant Science Terms - M

Macronutrient - collectively, primary and secondary nutrients

Macropore - large soil pore. Macropores include earthworm and root channels and control a soil’s permeability and aeration. . In a substrate, the larger spaces (or pores) that lies between component particles that hold air

Malformation - any deviation from the normal shape of a plant organ

Mallophaga - major order of insects that are wingless and have chewing mouthparts (chewing lice)

Mandible - first pair of jaws on insects: stout and tooth-like in chewing insects, needle or sword-shaped in sucking insects. The lateral (left and right) upper jaws of biting insects.

Market gardening - growing of an assortment of vegetables for local or roadside markets. Mesocarp. The center portion of the fruit wall

Maturity - for fruit, ripeness, usually the state of development that results in maximum quality; flowering phase of plant growth

Mechanical insect control - manual removal of insects and eggs from infested plants

Meristem - plant tissue in the process of formation; region where vegetative cells in a state of active division and growth, e.g., those at the apex of growing stems and roots and responsible for enlarging stem diameter

Mesophyll - between the epidermis layers, where photosynthesis occurs

Metamorphosis - process by which an insect develops. The term is a combination of two Greek words: meta meaning “change” and morphe meaning “form.” Metamorphosis is a marked or abrupt change in form or structure, like a caterpillar turning into a butterfly. (See also Complete metamorphosis, Simple metamorphosis)

Microclimate - spot within a garden that differs from the general environment and affected by landscape, structures, or other unique factors in the immediate area.  Some examples would be a wet spot where water collects during rain, a spot that remains warmer in the winter - often due to a structure, a spot that is sheltered from the wind, a spot that is affected by ocean salt spray

Micronutrient - nutrient, usually in the parts per million range, used by plants in small amounts, less than 1 part per million (boron, chlorine, copper, iron, manganese, molybdenum, nickel, and zinc)

Micropore - fine soil pore, typically a fraction of a millimeter in diameter. Micropores are responsible for a soil’s ability to hold water. In a substrate, the smaller spaces (or pores) between component particles that are occupied by water or air

Microscopic - organisms so small that they can be seen only with the aid of a microscope

Mixed buds - buds that produce both shoots and flowers

Mixed fertilizer - fertilizer that contains at least two of the three macronutrients (N, P, K)

Mixture, seed - combination of seeds of two or more species, for example Kentucky bluegrass and perennial ryegrass

Modified central leader - system of pruning used primarily on fruit trees. The central leader is encouraged for the first few years, then suppressed. This system allows for well-placed scaffolds and strong crotches, but keeps the tree’s crown relatively close to the ground for easy harvesting

Molt - shedding of exoskeleton during insect growth. The form assumed between molts is called an instar

Monochromatic - use of the various tints, shades, and hues of only one color

Monocot - see Monocotyledon

Monocotyledon - plants with one seed leaf. Also referred to as monocot

Monoecious - plants that have imperfect flowers (male and female) occurring on the same plant (e.g., corn)

Morphology - study of the origin and function of plant parts

Mosaic or mottle - irregular foliage coloration of light and dark areas of colors, usually light-green, yellow, or dark-green, against the normal green background color of the leaf 

Mound or stool layering - layering procedure in which the new shoots develop in spring and soil is mounded around their bases, excluding light and enhancing root formation

Mounded - plants with a rounded appearance, they are usually wider than they are tall

Mulch - material applied to the surface of a soil around plants to conserve moisture, reduce erosion, stabilize soil temperature, add organic matter, and suppress of weed growth.  It can be organic or inorganic material but is often made of bark or compost. Wood chips, bark chips, and shredded leaves are mulches are organic mulches; inorganic materials including rocks and sand are also used

Mummy - dried, shriveled fruit

Mushroom - soft, stalked fungal fruiting body of certain families of fungi characterized by gills. Most are mycorrhizal or are secondary decomposers

Mutation - genetic change within an organism or its parts that changes its characteristics. Also called a bud sport or sport

Mycelia - masses of fungal threads (hyphae) that make up the vegetative body of a fungus

Mycelium - visible vegetative body of a fungus, made up of threads called hyphae. (sing., hypha)

Mycology - study of fungi

Mycoplasma - see Phytoplasm

Mycorrhiza (Mycorrhizae, plural) - beneficial fungi that infect plant roots and increase their ability to take up nutrients from the soil


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