Evidence of bonsai in a 15th century Kyoto tearoom

I am reading A. L. Sadler’s “The Japanese Tea Ceremony: Cha-No-Yu”, published in 1933. The book has a description of the formal style tea room of Murata Shukō* (1423–1502) who is considered to be the founder of the Japanese tea ceremony. Here is the part of it, which got my attention:
 
“On the walls of this room there are said to have been black-and-white sketches by Engo Zenji**, while in the Tokonoma either a single picture or a set of two was displayed. In front of this was a stand with an incense burner and a flower vase, either one of the ordinary sort or a small one with a single flower. Boxes of stationery and Tanzaku or poem slips, ink stone and bookstand, a tray-garden***, and jars for leaf-tea are also mentioned, so that it is evident that this Tearoom was much like an ordinary study in its furnishings and not specialized as afterwards.”
 
For me, the significance of this passage is that the founder of Japanese tea ceremony had bonsai in his tearoom/study!

*    The ‘wabi-cha’ teachings of Murata Shukō were picked up by Takeno Jōō (1502-1555)  who in turn taught Sen no Rikyū (1522 -1591). Sen no Rikyū had an enormous impact on Japanese aesthetics and culture as a whole. Needless to say this impact extends to bonsai aesthetics as well.
**   as far as I know Engo Zenji was a Zen Master and a writer.
*** "tray-garden" is probably Sadler's literal translation of the word 'bonsai' or a similar term.