Flower puzzle

Here's a little puzzle for you: these three were blooming in the Linda Vista Gardens today. What do they have in common, and which is the odd one out?

The answer revealed! - The flowers are primrose, rose, and hellebore (or Winter Rose). So they all have "rose" in their names. And the odd one out is the rose, because it's most certainly not supposed to be flowering in January, whereas it's perfectly acceptable for the other two.