Simple flowers with four petals, should arrive with calyx cover still on or perhaps with just a little color showing. Stems are hairy, and should feel a little prickly when touched lightly. When the stems are cut poppies exude a white milky latex-type fluid, so one of the following methods is suggested to preserve this fluid within the stem:
Traditionally the stems are cut and then immediately cauterized, or singed with a naked flame, to seal the stem. However burning the stems damages the vascular system which is probably deleterious to the flowers. Alternatively, the ends of the cut stems can be placed into boiling water for about 15 seconds, which similarly cauterizes the stems. My preference would be to cut the stems under-water and leave there for some ten minutes, in which case the principle of displacement will hold the fluid inside the stem. After ten or so minutes consolidate the bunches into containers with a low sugar holding solution and reserve in the cooler.
These types of poppies are not harvested with leaves.