
I call it “indigo elephant flower”. What name would you give it?
The common name is “Japanese Dayflower”.
In Japanese “Tsuyukusa”, 露草 Tsuyu means “dew” or “rainy season”.
Kusa 草 means “grass”.

The scientific name is commelina communis. 学名
It is named after Dutch botonists Jan and Caspar Commelijin. オランダ植物学者
花言葉の「なつかしい関係」は、この植物の学名のもとになった伯父と甥のコメリンが二人ともアムステルダム薬草園の園長だったことにちなむともいわれます。

It’s also known as “Duckfoot herb”.
鴨跖草 kamo (duck)
It has been used in traditional Chinese medicine for sore throats and tonsillitis among other things.
On sunny days the flowers open in the morning. Naturally, like the name suggests, they last only one day.
The lovely Dayflower adds a striking accent of color to salads.
Boil the flowers and leaves, steaming is better!
三杯酢 Vinegar, soy sauce, and mirin (or sugar) as a dressing gives a refreshing taste to this summer salad.
There is an article about Plant Dyes used in Woodblock Prints. This article talks about “Ukiyo-e”,
pictures of the floating world. It sites evidence that this Japanese Dayflower was used to make dyes for various woodblock prints.
“The traditional organic blues, dayflower and indigo, can be confidently identified by FORS in the visible and
near-infrared ranges.”

Actor Ichikawa Danzō III as Adachi Hachirō, (MFA 11.19030),
1762 (Hôreki 12) 11th month, designed by Torii Kiyomitsu I, and pub-
lished by Urokogataya Magobei (30.2 x 14.2 cm). Example of a benizuri-e
Japanese woodblock print with a 3-color palette commonly made from
the 1740s to 1765.
(PDF) Plant Dye Identification in Japanese…. Available from: https://www.researchgate.net/publication/315754202_Plant_Dye_Identification_in_Japanese_Woodblock_Prints [accessed Aug 26 2018].
Derrick, Michele & Wright, Joan & Newman, Richard.
(2017). Plant Dye Identification in Japanese Woodblock Prints. Arnoldia. 74. 12.