BBC Gardeners' World

Midge

A common term for any number of gnat-like flies, which are usually found close to water sources.

Midrib

1) The main, central vein of a leaf.

2) The central stem of a pinnate leaf from which leaflets arise.

Mildew

A fungal plant disease that causes a powdery coating on the surfaces of affected plants. Commonly occurs where plants have been exposed to damp conditions. It can be prevented by having good ventilation.

Millipede

A myriapod, with many legs organised in double pairs on each body segment. Commonly black or dark grey, it attacks the roots of many plants, especially vegetables.

Mimicry

Used in reference to plants that look like other plants or inanimate objects, eg, the deadnettle, which looks like the stinging nettle.

Mite

The common name for tiny members of the Acarina order. They're distinguished from insects by having eight legs and no antennae. They may cause damage to plants, and are best controlled by chemical acaricides.

Modular tray

A large tray divided into cells in which seeds may be planted. The cells train the roots downwards, strengthening them and causing limited disruption to the plant when transplanted outside.

Mollusc

A member of the Mollusca grouping, which includes Gastropoda - soft bodied, unsegmented animals, many of which live in hard shells, eg, slugs and snails.

Molluscide

A chemical treatment used to kill slugs and snails.

Monocarpic

Used in reference to plants that die after fruiting. Especially applicable to plants, which grow for several years before producing fruit.