This form of Primula flower has been around for a long time - it was first recorded in John Gerard's 1597 herbal. The impression of one identical flower within another is due to a mutation where the calyx of the Primula flower is transformed into a second petaloid structure. The name likens the appearance of the flower to the way Elizabethan gentlemen used to wear their stockings (hose) - one inside the other with the outer stocking turned down - hence hose-in-hose. I think it is a charming curiosity, and the fresh yellow is a sunny treat for this first day of spring (arbitrary I know, but it is the first of September).
It is, as the name suggests, a flower from the Northern Hemisphere.
Our New Zealand native golden harbinger of spring is the kowhai and suddenly, it seems, flowers are beginning to emerge. At present they make a very dramatic contrast against the bare branches of the trees as the leaves are yet to open.
A happy sight for humans and hungry tui alike.