Playmobil used a lot of "non-Playmo" items as background scenery in their early outdoor dioramas. I love those pics on the back of the old boxes!

As far as I know, the only trees they manufactured for retail sale were made of moulded plastic and the ones in that pic look more like the kind you'd find in a shop selling railway accessories.
I suppose it is possible that they did make those trees in their own factory, but that they were only used for Playmobil displays in shops. My guess is that they sourced them from elsewhere because they wouldn't have been needed in very large quantities.
