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"[Plin. Nat. 20.77.] - THE POPPY CALLED RHŒAS: TWO REMEDIES.
The poppy which we have spoken of under the names of “rhœas” and the “erratic” poppy, forms an intermediate variety between the cultivated and the wild poppy; for it grows in the fields, it is true, but it is self-set nevertheless. Some persons eat it, calyx and all, immediately after it is gathered. This plant is an extremely powerful purgative: five heads of it, boiled in three semi-sextarii of wine, and taken in drink, have the effect of producing sleep.”
(The Natural History. Pliny the Elder. John Bostock, M.D., F.R.S. H.T. Riley, Esq., B.A. London. Taylor and Francis, Red Lion Court, Fleet Street. 1855.)