The record -- titled Flora of Tropical East Africa -- was begun in 1948, when botanists estimated the survey might take as long as 15 years. It took 135 botanists from 21 countries six decades to catalog every plant species in Uganda, Kenya and Tanzania.
In its final form, the catalog, kept at Britain's Royal Botanic Gardens, Kew, contains 12,104 species, of which 1,500 are species new to science discovered in the course of the survey.
The catalog is vital for conservation efforts in the region, the current editor of the catalog said.
"The FTEA, like all floras, is about communication -- without proper identification and names there is no communication about plants, and without communication all work on and with wild plants rests on quicksand," Henk Beentje said.
Around 2,500 of the species in the catalog are found nowhere else on Earth and face threats from human pressures without protection, researchers said.
"Now all further work on the wild plants of this region will be built on a solid foundation -- not just botanical work but work on local uses by local people, ecology, vegetation work, zoology, and, of course, conservation," Beentje said.