from Kaempfner's 'Amoenitum Exoticarum' 1712
from Revue Horticole 1885
From Wikipedia:
Engelbert Kaempfer (1651 - 1716) was a German naturalist, physician, and writer known for his tour of Russia, Persia, India, South-East Asia, and Japan between 1683 and 1693.
He wrote two books about his travels. Amoenitatum Exoticarum, published in 1712, is important for its medical observations and the first extensive description of Japanese plants (Flora Japonica). His history of Japan, published posthumously in 1727, was the chief source of Western knowledge about the country throughout the 18th and mid-19th centuries when it was closed to foreigners.
Taken from Engelbert Kaempfer's 'Amoenitatum Exoticarum' of 1712. This is the first Western published image of Poncirus trifoliata that I can find.
All the image copies I have seen are covered in 'print-through' text from the other side of the page. Here I have removed this text from the background, but some remains within the drawing itself.
Poncirus trifoliata or Citrus trifoliata - Early Botanical Drawings
Citrus triptera from the 'Revue Horticole' published in Paris in 1885. The earliest colour image of the species I have found.
Poncirus variants from Somoku kin'yoshu - part 1
Poncirus variants from Somoku kin'yoshu - part 2
Poncirus variants from Somoku kin'yoshu - part 3
Somoku kin'yoshu (前編) 草木錦葉集 (Brocade-leaf Collection of Plants and Trees (part I)), 1829:
From Engelbert Kaempfer's 'Amoenitatum Exoticarum' 1712:
From Revue Horticole, 1885:
These images are based on The British Museum copy of this Japanese woodblock-printed book. I have cleaned them up a bit - and coloured the fruits!

The translated title given by the British Museum is 'Brocade-Leaf Collection'. I have come to the conclusion this is a term used to include variegated leaved plants and other unusual decorative features - such as the spotted leaves of the top central image. Perhaps a better translation of the title would be 'Ornamental Leaf Collection.'
Japan's online digital library
gives an OCRd version of the book title which, when translated by Google, becomes 'Illustrated collection of variegated plants'.
The bottom right image could be the variegated form of 'Flying Dragon', which is now very rare - at least outside Japan. I have never seen a variegated or a spotted form of the standard Poncirus trifoliata but they may exist.
"The Comte de Castillon (1877, p. 73, figs. 11, 12) reproduced Japanese figures and gave Latin varietal names to two other sports of this species grown in Japan - the variety microcarpa, which has minute fruits, and the variety punctata, which has leaves dotted with golden-yellow spots, called in Japan sunago or "gold-dust" trifoliate orange."
Citrus triptera variants
The Citrus Industry, volume 1, mentions this Revue Horticole article written by  the Comte de Castillon. It says:
The 1877 edition of Revue Horticole reproduces part of the Japanese book, and also complains about the lack of detailed information.
Click on the picture for complete French text.

page created  8th Dec 2015

If anyone, in Japan or elsewhere, has ever seen tiny-fruited or dotted-leaf forms of Poncirus trifoliata, I would love to hear from them!
Translations of the Japanese labels would also be welcomed.