an entry about Ichang papeda I was able to find from an old source:
some excerpts:
" This species is cultivated in the vicinity of Ichang, and it bears a very large lemonlike fruit that is of sufficiently good quality to cause it to be shipped to markets several hundred miles distant.
In China this species occurs in an undoubted wild state in the hills of the Upper Yangtze Valley from Ichang west and southwest in Hupeh, Szechwan, and Kwichow, growing at altitudes of 1,500 to 6,000 feet. In Assam a closely related but slightly different form is found at an altitude of 5,000 to 6,000 feet in the Khasi Hills.
The species thus ranges over a region at least 1,500 miles long and some 500 miles wide.
This plant is reported in all parts of its range as growing in a truly wild state and is cultivated on a small scale around Ichang along the Yangtze River, where the fruit is called the "Ichang lemon" by foreigners.
The typical Citrus ichangensis as it occurs in southwestern China is a small tree or a large shrub, usually 5 to 15 feet high (1.5 to 5 meters), but sometimes reaching 20 feet. It also occurs wild in fruiting condition only 2 to 3 feet high on the cliffs of the Yangtze Gorges. "
The article also makes mention to both a wild and cultivated form with slightly better fruit quality.
" Mr. E. H. Wilson informs the writer that the form of this species cultivated in the Ichang region yields an excellent fruit known to foreign residents of the Yangtze Vallet as the "Ichang lemon." These fruits are shipped down the river to Hankow and west well into Szechwan, and are so much esteemed as to command good prices.
So far as is now known, Citrus ichangensis is native farther north than any other evergreen species of Citrus, only the deciduous Citrus trifoliata having a more northerly range. Besides having the northernmost range of any known evergreen species of Citrus it occurs at the highest altitudes reported for any wild species of the genus. In the Hsingshan District, in latitude 31° 10', Mr. Wilson collected this plant at an altitude of 4,200 feet, and Pére Cavalerie found it in central Kweichow at a height of 5,577 feet. "
Journal of Agricultural Research, Department of Agriculture, Volume 1, Washington D.C., October 10, 1913
Citrus ichangensis, A promising, hardy, new species from Southwestern China and Assam, article by Walter T. Swingle
(Note who wrote the article, this is the same man after whom the "Swingle citrumelo" was named)