Plus sign in the context of Infix notation

Addition, usually denoted with the plus sign +, is one of the four basic operations of arithmetic, the other three being subtraction, multiplication, and division. The addition of two whole numbers results in the total or sum of those values combined. For example, the adjacent image shows two columns of apples, one with three apples and the other with two apples, totaling to five apples. This observation is expressed as "3 + 2 = 5", which is read as "three plus two equals five".

Besides counting items, addition can also be defined and executed without referring to concrete objects, using abstractions called numbers instead, such as integers, real numbers, and complex numbers. Addition belongs to arithmetic, a branch of mathematics. In algebra, another area of mathematics, addition can also be performed on abstract objects such as vectors, matrices, and elements of additive groups.

Robert Recorde (c. 1510 – 1558) was a Welsh physician and mathematician. He invented the equals sign (=) and also introduced the pre-existing plus (+) and minus (−) signs to English speakers in 1557.

The hyphen ‐ is a punctuation mark used to join words and to separate syllables of a single word. The use of hyphens is called hyphenation.

The hyphen is sometimes confused with dashes (en dash –, em dash — and others), which are wider, or with the minus sign −, which is also wider and usually drawn a little higher to match the crossbar in the plus sign +.

+ Laburnocytisus 'Adamii' (also known as Adam's laburnum or broom laburnum) is a horticultural curiosity; a small tree which is a graft-chimaera between two species, a laburnum, Laburnum anagyroides, and a broom, Chamaecytisus purpureus (syn. Cytisus purpureus), which bears some shoots typical of the one species, some of the other, and some which are a peculiar mixture of both "parents". The plus sign (+) indicates the generic name is made for a graft-chimaera. The plant can also be described by the formula Laburnum anagyroides + Chamaecytisus purpureus.

+ Laburnocytisus 'Adamii' is a legume, a member of the pea family Faboideae (or Papilionaceae, formerly Leguminosae). Only one cultivar, 'Adamii' is known to have arisen from this graft. It is sometimes described as if it were one species, (+ )Laburnocytisus adamii; however, it is not one species and this notation is not conforming to International Code of Nomenclature for Cultivated Plants.