BBC Gardeners' World

Reticulate

The term used to describe the network pattern of veins on a leaf.

Retuse

Of leaves or petals that have an indented or notched tip.

Reversion

1) When a cultivated plant reverts to its original form.

2) A viral disease that affects blackcurrants, reducing the quality of the plant and its yield.

Revolute

Leaves or petals rolled backwards, downwards or outwards.

Rhizoctonia

A general term for a number of fungal diseases, which are normally soil-borne, but also aerially transmitted. It affects a large range of plants, but commonly cereal cops. May cause damping off and blight, but can be controlled using fungicide.

Rhizome

A creeping stem that grows along or just beneath the soil surface, with roots arising from it. Is also a storage function.

Rib

The main vein running through a leaf.

Rogue

1) A plant that fails to conform to type.

2) An inferior specimen among a group of seedlings.

Root fly

An insect that attacks plant roots. This pest can be controlled using pesticides.

Root nodule

Knobbly growth arising from the roots of leguminous plants. The root nodules contain bacteria used in nitrogen fixation.