Hort.
Hort., in the taxonomy of plants, is an abbreviation used to indicate a name that saw significant use in the horticultural literature (usually of the 19th century and earlier), but was never properly published.
Origins and usage
"Hort.," short for Hortulanorum, was proposed in order that a non-wild, cultivated plants known and described in agriculture or gardening circles can be examined by taxonomists, to be examined if they can be established as species, and published.
The proposal was made at the 1928 "International Congress of Horticulture of Vienna" by citrus scholar Tyozaburo Tanaka.
For example, for the clementine, the following binomial name was adopted by Tanaka:
With respect to the citrus, Tanaka's system is no longer considered viable (For the clementine example above, the hybrid name Citrus × clementina would be favored by most consensus). However, it is still useful as an expedience for designating the numerous Japanese "types" (hybrids, cultivars, accessions, phenotypes).
