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Pruning shears, also called hand pruners (in American English), or secateurs, are a type of scissors for use on plants. They are strong enough to prune hard branches of trees and shrubs, sometimes up to two centimetres thick. They are used in gardening, arboriculture, farming, flower arranging, and nature conservation, where fine-scale habitat management is required.
Loppers are a larger, two-handed, long-handled version for branches thicker than pruning shears can cut.
Scissors only used for gardening work have existed since 1819, when the French aristocrat Antoine Francois Bertrand de Molleville was listed in "Bon Jardinier", as the first inventor of secateurs. During the late 1890s, secateurs were sold all over Europe and the US. Nowadays every pro- and semiprofessional gardener, vintner and fruit farmer uses secateurs.
There are three different blade designs for pruning shears: anvil, bypass and parrot-beak. Anvil pruners have only one blade, which closes onto a flat surface. They tend to crush the stem, but remain reliable when they are slightly blunt. Anvil pruners are useful for cutting thick branches. Bypass pruners usually work exactly like a pair of scissors, with two blades "passing by" each other to make the cut. At least one of the blades will be curved: a convex upper blade with either a concave or straight lower one. Some bypass designs have only one blade, the lower jaw being broad (like an anvil) but passing the upper jaw. Parrot-beak pruners consist of two concave passing blades, which trap the stem between them to make the cut. These are suitable only for narrower stems. 
Secateurs have short handles and are operated with one hand. A spring between the handles causes the jaws to open again after closing. When not in use, the jaws may be held closed by a safety catch or by a loop holding the handles together. Some types are designed for right-handed or left-handed use only, and some incorporate a rotating handle to reduce friction and minimize hand stress during repetitive use. There are also longer versions called telescopic pruners, which are adjustable for long-reach and operate by means of a rod system inside of a telescoping pole between the handles and the blades. An early version of these was known as an averruncator.