Picea abies 'Compacta' is used as a collective term to describe the myriad globose- to broadly conical forms of Norway spruce with dense branching and short needles that exist in the international nursery trade. Such plants have been well-known and popular throughout history and no individual clone can be identified as the origin of them all. At some point taxonomists will formally assign these trees under a 'œform-status,' i.e. Picea abies forma compacta. However this has not yet happened.
Humphrey Welch and Gordon Haddow correctly state in The World Checklist of Conifers that, "according to the literature the name 'compacta' is loosely used in the trade for several compact clones."
In 1864, Carl Edward Adolph Petzold and Georg Kirchner formally described this cultivar in their book, Arboretum Muscaviense They claim that 'Compacta' originated a seedling selected by James Godfrey Booth of Booth & Son Nursery, Hamburg, Germany. Given the number of widely varying clones currently available, it's quite likely that Booth's is no longer distinguishable.