IO 
Journal of Agricultural Research 
Vol. I, No. i 
practiced by the Chinese gardeners, who would naturally have chosen the 
most promising of the wild forms to propagate. Unlike many other culti¬ 
vated citrous fruits, this species shows no evidence of having been hybrid¬ 
ized; it is rather a selected form of a wild species. 
Both the wild and cultivated forms of Citrus ichangensis will be secured 
as soon as possible for trial in this country. Careful exploration at higher 
altitudes near the northern limit of the species in China should bring to 
light exceptionally hardy forms that would be invaluable to breeders of 
hardy citrous fruits. 
THE RELATIONSHIPS OF CITRUS ICHANGENSIS 
Citrus ichangensis stands apart from all the other known members of 
the genus. Its huge, thick seeds are unlike anything heretofore known 
in Citrus, and its long, slender leaves with their very large, broadly 
winged petioles, often exceeding the blade in area, distinguish it at once 
from most of its congeners. 
Citrus histrix DC., a curious and little-known East Indian species, 
also has leaves with broadly winged petioles, often larger than the blades, 
but differs greatly from Citrus ichangensis in having very small flowers, 
often only 4-parted, with perfectly free stamens. Even the broadly winged 
petioles of C. histrix are distinctly different, being more gradually nar¬ 
rowed toward the base and usually more abruptly truncate at the tip, 
making them somewhat triangular in outline, whereas those of the 
Chinese species are often oblong or elongate elliptical. 
The other species of Citrus having very large, broadly winged petioles, 
such as C. celebica Koord., C. papuana Bail., and C. macroptera Montr., 
native to the Malayo-Polynesian region, are apparently closely related to 
C. histrix , if, indeed, they are not to be considered as forms of it. They 
all agree with C. histrix in having winged petioles more or less triangular 
in outline and show no close affinity with Citrus ichangensis . 
The bulky seeds of Citrus ichangensis with their large brown caps and 
thick deformed cotyledons are so much larger than those of its congeners 
that they can not be mistaken for those of any other species of Citrus. 
They are much more like those of the African species of hard-shelled 
citrous fruits belonging to the genera Balsamocitrus and Aeglopsis. 1 
PREVIOUSLY PUBLISHED NOTICES OF THE SPECIES 
In 1907 L. Diels 2 referred to Citrus histrix DC., two numbers collected 
by A. v. Rosthorn in Szechwan in 1891, noting that one (No. 1264) had 
narrower leaves with inconspicuous venation and the other (No. 175) 
1 Stapf, Otto, 1906. Plantae novae Daweanae in Uganda Iectae. Jour. linn. Soc. [London] Bot., v. 37, 
p. 505, pi. 22. 
Swingle, Walter T., 1912. I,e genre Balsamocitrus et un nouveau genre voisin, J 3 gIopsis. Soc. Bot. 
France, t. 58 (s. 4, t. 11), (M&n. 8d.) p. 236 and 241, fig. B and pi. 3. 
2 Diels, I,., 1900. Die Flora von Central-China. Bot. Jahrb. [Engler], Bd. 29, Heft. 3/4, p. 424. 
