She might also have had a purple Wallflower, and even a Wallflower of so
pale a yellow as to be almost white.

If you and I were clever gardeners and had plenty of time and patience,
we could get purple or nearly white wallflowers from these
yellow-flowered plants upon the wall. It would perhaps take us many
years, but we should succeed at last. This is how we should set about
it.

Suppose that we wished to have a Wallflower nearly white. We should look
carefully along the wall in spring, when the blossoms are out, until we
found the very palest yellow blossom we could see. We should mark that
plant, and when the flower was over and the seed was ripe, we should
collect the seed. Among the plants grown from this seed we should choose
again the plant that had the palest flowers, and should save the seed
from _that_. We might have to go on doing this for twenty years or more,
but in time we should have a Wallflower so pale as to be almost white.

_Quite_ white we should never get our Wallflower, for no _pure_ white
flower can be obtained from a yellow one. However pale our Wallflower
might be there would still always be just a tinge of yellow or cream
colour in it.

If, on the other hand, we wanted a purple or a very dark brown
Wallflower, we should save seed from those blossoms which were nearest
to the colour we wanted--dark brown or with a tinge of purple in them.
We should sow seed from the darkest blossoms again and again, and at
last we should get what we wished to have.

[Illustration: RED VALERIAN.]