For years, the plant Brunnera macrophylla or Siberian Bugloss remained in relative obscurity. The plain green-leaved form was a little dull for most, and the variegated forms at the time, B. macrophylla 'Variegata' and B. macrophylla 'Hadspen Cream' were rare.
The advent of tissue culture began to change that a decade or two ago, although many found 'Variegata' to be too unstable, both in production and in the garden, to be much good. I grew both in my Queenston garden for years, and while 'Variegata' was the more dramatic, 'Hadspen Cream' was ultimately the better plant. Be aware that most pictures of the latter on the web are deceivingly of the former.
And then came 'Jack Frost'...
I can remember seeing this plant for the first time, what may have in fact even been the very first plant, during a tour of Walters Gardens many years ago. A single pot sat on a bench, and Mary Walters acknowledged after I noticed it (WOW!), that it was a new plant they had discovered as a sport of the old variety 'Langtrees'. They intended to release it in a couple of years. And so indeed they did -- and the world of Brunnera macrophylla has never been the same.
Not long afterwards, we planted several in a shady garden amongst some White Pines, and they have performed admirably -- returning reliably each spring to produce a pleasant mound of wonderfuly silvery foliage, accompanied in the spring by loose clusters of tiny but brilliant blue flowers. I've never noticed a sinlge pest or disease bothering this plant, and by late summer, after weeks of high heat and humidity, and occassional periods of drought, the near dinner-plate size leaves remain in excellent condition.
A couple other varieties followed quickly on the heels of 'Jack Frost', namely 'Silver Wings' and 'Looking Glass', both of which I found rather uninspiring, with the former being too strange, and the latter being too similar (to 'Jack Frost').
More recently however, Walters Gardens has been at it again, and just released 'Emerald Mist', an "improved" form of the old 'Langtrees' with a more significant splash of silver spotting across the leaf. Even more exciting is a variegated form of 'Jack Frost' they are called 'King's Ransom', available this year exclusively through Great Garden Plants. Both of these are near the top of my current "wish list".