Vallmo – Papaver – is ‘poppy’. The word gives me a nostalgic picture of a barefoot shepherd(ess) standing on a sandy hill blowing in a horn to collect the cattle. Why not? Vall means ‘field of grass’, the verb att valla ‘to shepherd’, ‘to lead animals to graze’; and mo means ‘pine heath’. But those associations were a folk etymology; now I know better:
Vall in vallmo is related to valen - ‘numb with cold’, valhänt – ‘clumsy’, ‘awkward’ and Swedish and Norwegian dialect vale – ‘deep sleep’, ‘torpor’. The origin is obscure, but the meaning all too obvious.
Mo in vallmo is a common indoeuropean word for poppy, e.g. German Mohn.
Poppy was borrowed from Latin Papaver already in Old English times. Papaver is of unknown origin – maybe Etruscan.
PS: Re Mohn - Don't miss Emil Nolde at Akvarellmuseet in Skärhamn this summer!