macro-elements or macro-nutrients - there are certain mineral elements that are essential for plant growth. Some of these nutrients are needed in relatively large amounts for plant growth and these are called the macro-elements or macro-nutrients.

Others called micro-nutrients, are required in relatively small amounts but both groups are essential for proper, healthy plant growth.

The most common macro-elements include those usually found in a bag of fertilizer; nitrogen (N), phosphorus (P), and potassium (K).

Other macro  macro-nutrients include calcium, magnesium and sulfur which are found in adequate amounts in most soils. They occasionally need to be supplemented but only if shown by the results of a soil test.

maculata - Latin term for middle. The term aureomaculata would mean a gold colored in the middle of the leaf.
male flower - the male part of the flower is called the stamen which consists of an anther and filament. The pollen is produced on the anther. 

See Female Flower

marginal variegation - variegation that occurs on the outer edge i.e. the margin, of a leaf.

See medial variegation and splashed or streaked variegation in hostas.

mature - 1) Plants that have reached the stage of development where they are capable of sexual reproduction i.e. flowering and setting seed.

- 2) Also, a mature plant or clump is one that has reached the generally accepted maximum size for that cultivars or species.

See Juvenile

 
mealybug - a small insect about inch long that is covered with white, waxy fibers that give it a fuzzy appearance. It is a sucking insect that draws sap from the plant and can be destructive in large numbers.
mechanical injury - damage to a plant caused by forces other than disease including lawnmowers, winds, ice, pruning, etc.
medial variegation - a leaf or leaves having a lighter colored center as compared to the edges i.e. margin, color.
medio-variegated - See medial variegation above.
medium - See growing medium or media
 
medium size - according to the The American Hosta Society, there are five size categories of hosta including Giant, Large, Medium, Small and Miniature.

Medium hostas form a clump that is 10 to 18 inches in height and a leaf area of 25 to 81 square inches.

melting out - the death (necrosis) of the white or lighter colored center of hosta leaves. This may be caused by excessive sunlight or may be the result of cold temperatures.
meristem - this is the tissue in plants that has the ability to produce new cells. The cambium, root tips and buds of plants contain these cells and are the centers of growth. (adj. meristematic)
metamorphosis - the process by which insects proceed from egg form to adult form. Some insects go through complete metamorphosis where early stages look nothing like the adult. White grubs eventually becoming beetles is an example.

Others have incomplete metamorphosis where the young form merely gets larger to become the adult. A newborn grasshopper looks like and adult, only smaller.

microclimate - localized conditions in the landscape can result in variations from the average climate in the surrounding region. Topography, exposure to wind or sun, proximity to buildings or fences, urban conditions, etc. are factors which may change the climate of a small site in the home landscape.
 
micro-nutrient or micro-element - there are certain mineral elements that are essential for plant growth. Some of these nutrients are needed in relatively large amounts for plant growth and these are the macro-nutrients. Others, micro-nutrients, are required in relatively small amounts but both groups are essential for proper, healthy plant growth.

This group includes Boron (B), Copper (Cu), Chlorine (Cl), Iron (Fe), Manganese (Mn), Molybdenum (Mo), and Zinc (Zn).

Generally, these are in adequate supply in the soil. However, a deficiency of these elements will result in specific symptoms on the plant. Also, excessive amounts may result in toxicity to the plant.

They occasionally need to be supplemented but only if shown by the results of a soil test.

micro-pore - a pore is an opening or hollow space in the soil. Some of them are relatively large and are called macro-pores while other are quite small and are known as micro-pores. Generally, in the soil, micro-pores are filled with either air or water which is held tightly to the surrounding surfaces.

- See soil pore spaces.

mid-rib - center vein of a leaf. It is also called the medio or medial area of the leaf.
mineral soil - soil made up principally of weathered rock particles such as sand, silt and clay. See organic soil.
miniature size - according to the The American Hosta Society, there are five size categories of hosta including Giant, Large, Medium, Small and Miniature.

Miniature hostas are the second smallest group. They form clumps that are 4 to 6 inches in height.

 
misted - 1) Misted colored leaves have small, short segments of dark pigmented tissue on a lighter background.

2) May refer to the application of short periods of sprayed water to keep hardwood or sometimes, softwood cuttings moist to encourage rooting.

mites See spider mites
miticide - the suffix, icide, means "to kill". Miticides are meant to kill the eight legged creatures called spider mites. These products are somewhat different from insecticides which are meant to kill the six legged critters called insects.
monocotyledon - a cotyledon is a "seed leaf" and seed bearing plants can be divided generally into two groups. Monocotyledons (generally grasses and grass-like plants) and dicotyledons (all other seed bearing plants).

Somewhat ironically, hostas are monocotyledons even though many of them have very large, non-grass-like leaves.
 
Monocotyledon Dicotyledon
Embryo with single cotyledon Embryo with two cotyledons
Pollen with single furrow or pore Pollen with three furrows or pores
Flower parts in multiples of three Flower parts in multiples of four or five
Major leaf veins parallel Major leaf veins reticulated (webbed)
Stem vascular bundles scattered Stem vascular bundles in a ring
Roots are adventitious Roots develop from radicle
Secondary growth absent Secondary growth often present
monoculture - growing one species of plant in an area to the exclusion of others. This results in a higher possibility of a serious insect or disease problems causing severe devastation.

For example - At one time, many city streets were lined exclusively with American elm (Ulmus americana) trees. When Dutch elm disease was introduced to the United States in the 1950s, it swept through these areas quickly killing almost all of this species of tree.

monoecious - bearing separate male (staminate) and female (pistillate) flowers on the same plant. Oak trees produce separate flowers as does sweet corn where the tassel is the male flower and the silk is the female.

Examples include Birch (Betula), Hornbeam (Carpinus), Hophornbeam (Ostrya), Hickory (Carya), Oak (Quercus), Beech (Fagus).

 See dioecious.

 
Morden - a common cultivar name for plants originated at the Canada Experimental Farm at Morden in Manitoba, Canada.
mosaic - the common symptom caused by a virus infection of plant tissue. Also called mottling because it consist of non-uniform streaks and patches of yellow intermingled with the normal green color of the leaf or stem.

The variegation of certain plants or cultivars may be caused by a virus. Hosta 'Cynthia' exhibits this trait. Plants infected with a virus may also display a mottled color pattern but some hosta cultivars that are mottled do not have a virus.

mottled See mosaic above.
mucronate - coming abruptly to a sharp point. The leaves of certain hostas have a distinct point at the end which would be described as "mucronate".
mulch - any material used to cover the soil for purposes such as moisture conservation, esthetics, cooling the soil or weed suppression.

The material may be wood chips, shredded bark, peanut hulls, cocoa bean hulls, peat moss, leaf-mould, garden compost, landscape cloth or plastic sheeting among others.

mutation - applies to a "spontaneous" change to the genetic material (DNA) of an individual which may be passed from generation to generation through sexual reproduction.
mycoplasma - these are a type of bacteria that do not have cell walls and are extremely small that occasionally cause plant disease.
mycorrhizae - a type of soil fungus that forms a symbiotic (mutually beneficial) relationship with the roots of certain plants. When this fungus is growing on the root, it helps the plant to more efficiently absorb nutrients and water.

Generally, a specific fungal species works on a specific tree species. Efforts are being made to isolate these fungi and make them commercially available to be placed in the transplant hole for specific trees.

 

 

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