420 Journal of Agricultural Research vqh.no. 5 
“Galleriewaldungen” at Uando, near the divide between the Congo and 
the Bahr-el Ghazal drainage basins. In 1880 Soyaux collected specimens 
of another species in Gabun (French Congo). In 1882 Pogge collected 
material at Lulua in Congo proper, and in 1890 Preuss found still another 
very distinct species on the shores of Elephant Lake in Kamerun. Early 
in 1895 Prof. Adolph Engler described four new species of Limonia to 
include these plants. 1 2 In November of the same year he segregated these 
African species of Limonia as a new section, Citropsis, in contradistinction 
to the true Limonias of the Asiatic mainland. 3 
Since then several additional species have been described from tropical 
Africa, and it is now clear that these plants occur not uncommonly 
throughout central Africa from the Ivory Coast in the west to Uganda 
in the east. 
In connection with a study of the plants related to Citrus, these African 
species of the Citropsis section of Limonia have been carefully examined. 
The material of this section in the principal European collections of 
African plants has been studied and a number of representative speci¬ 
mens secured, through the generosity of M. Emile de Wildeman, of 
Brussels, and M. Auguste Chevalier, of Paris. Mr. B. T. Dawe, formerly 
Forest Administrator of Uganda, who had discovered a new species 
(Limonia ugandensis Baker) in the forests bordering the north shore of 
Victoria Nyanza, sent to the Department of Agriculture at Washington 
in 1910 both good herbarium specimens and viable seed. 
As a result of these investigations, which have been in progress some 
three years, it is now clear that these plants have been wrongly placed 
in the Asiatic genus Limonia. Instead of constituting a section of this 
genus, they are in reality only remotely related to the type species from 
Asia (Limonia acidissima L-) and are, on the other hand, closely and 
clearly related to Citrus. 
The Limonia acidissima (Hesperethusa crenulata (Roxb.) Roem.) of 
India has small, globose fruits only 12 mm. or less in diameter, becoming 
a purple-black, bitterish berry when ripe. Each of the four cells of the 
fruit contains a single seed surrounded with mucilage. There are no 
pulp vesicles. The fruits are, thus, of an entirely different structure 
from Citropsis and are like those of many Asiatic genera, such as Lavanga, 
Triphasia, Severinia, etc., which constitute a natural group. 
Besides the very important differences in the structure of the fruit, 
Limonia acidissima differs from Citropsis in having free-spreading stamens 
with slender filaments. None of the other Asiatic species usually referred 
to Limonia are any more closely related to Citropsis than is Limonia 
acidissima . 
1 Engler, A, Diagnosen neuer Arten. In Notizbl. K. Bot. Gartens u. Mus. Berlin, Bd. i, No. i, p. 28-29. 
Jan. 2, 1895. 
2 Engler, A. Rutacese. In Engler, Adolf, and Prantl. Natiirlichen Pflanzenfamilien. T. 3, Abt. 4, p* 
189-190, fig. 109, E-H. Leipzig, 1895* 
