BBC Gardeners' World

Palmate

A leaf divided into many lobes of the same shape, which usually emanate from one point at the end of a leaf stalk or petiole.

Pan

1) A dish used for raising seedlings and shallow-rooted plants.

2) A compacted layer of subsoil produced by digging to the same depth over time, through which roots can't penetrate.

3) A surface pan may occur when topsoil is compacted by walking or rolling, or following heavy rain.

Panicle

An influorescence having several branches that are either opposite or alternate. A loose cluster of flowerheads blooming from the base upwards.

Parasite

An organism that grows and feeds on another. Completely parasitic plants have no leaves or chlorophyll, relying entirely upon the host for nourishment. Semi-parasitic plants have leaves and are able to produce some of their own food.

Paripinnate

See Pinnate.

Parthenocarpic

The term used to describe plants that produce seeds without fertilisation. Examples include the greenhouse cucumber or cultivated banana.

Pathogen

An organism, viral, bacterial, fungal or parasitical, that attacks plants. It may be water, air or soil borne, or carried by insects.

Peat

The accumulation of partially decayed and carbonised vegetable matter. Deposits form in peatlands or wetlands, known variously as bogs, moors, mires and muskegs, and are used as fertiliser.

Peat wall

A wall comprising blocks of peat, that surrounds a peat bed.

Pedate

A palmate leaf with distinctive clefts in each lobe.