The record derives from TICA
(data supplied on )
which reports it as a synonym (record
CF712FD1-DAF2-4A7A-9552-6B137DD40D78) with original publication details: "Cariot & St.-Lag., Étude Fl., ed. 8. 1889" 495 1889.
This name record (from TICA) was not included in version 1 of The Plant List. It is possible the same name was included from a different data source, to check this you can search for Lactuca chaixii in version 1 of The Plant List.