Actually Viola Plans, but pansy is the more familiar term. Violas are smaller and stand up bettter in the weather, according to Graham Rice:
An initial lesson that I took from my time spent on RHS trials judging panel is that, in early winter at least, the small-flowered pansies, which are closer in style to violas, have been more impressive than those with larger flowers. Nine small flowers look far more colourful than two large ones.
This is why. First, the flowers of many pansies are so large that the petals simply do not have the strength to support themselves. The tops of the flowers hang over, the effect is lost. Violas, on the other hand, produce such a constant succession of flowers, if one is damaged by the weather another soon opens. And, with alpine species in their ancestry, violas are simply tougher.
I ordered violas:
Viola x wittrockiana Jolly Joker F2
Viola x hybrida Penny Sunrise F1
Viola cornuta Bambini Mixed
Among other things Mr. Rice declares is this:
Seeing so many winter-flowering pansies together on dull winter days led me to another conclusion: dark colours make no impact. Crimson, deep purple and dark blue, especially if they feature black-blotched faces, never really stand out, but white, primrose, sky blue and pale pink sparkle on even the most overcast days.
He does not mention yellow, which Miss Billie says is the color to plant for wintertime; nor orange, which fits into my color scheme with the purple and orange Jolly Joker. I have another packet of blues for yet another area. I could not have too many violas.