A conjunction is a word used to connect words, phrases, clauses and sentences. Those most commonly used are ‘and’ (et, atque), ‘or’ (aut, vel) and ‘but’ (sed). Several may consist of two or three words in English, e.g. ‘and also’ (atque, ac), ‘or if’, ‘or else’ (seu, sive), ‘so that’ (ut).

In general, where two nouns are joined by a conjunction, the second takes the same number and case as the first. Unlike prepositions, conjunctions have no control over the grammar.

The conjunction ‘and’ may also be shown by adding -que to the end of the last word of a phrase or clause:

folia et flores or folia floresque leaves and flowers

and in place of vel, -ve may be added;

folia vel flores or folia floresve leaves or flowers

Some may be used in pairs, but in Latin the same word is repeated; thus we have ‘both…and’ (et…et), ‘either…or’ (vel…vel), ‘neither…nor’ (nec…nec).

et sepala et petala flava both sepals and petals yellow

nec flores nec fructus visi neither flowers nor fruit seen

folia pilis vel simplicibus vel glandulosis leaves with either simple or glandular hairs

With ut (‘so that’, ‘in order that’), a complication arises since it is followed by a verb in the subjunctive, a difficult area of Latin grammar that is best avoided in botany. It is simpler to write the description in such a way that you don’t have to use it.