Variegation
Judy Glattstein (Mon, 09 Apr 2007 10:32:56 PDT)

My understanding is that while chlorophyll = green is the primary
photosynthetic system plants utilize, there is a secondary route that
uses yellow. Thus yellow variegated plants grow reasonably vigorously.
White being the absence of pigment, white variegated plants are less
efficient, grow more slowly, may revert to all-green - Hemerocallis
'Kwanso' and Kerria japonica 'Picta' as examples.

Also, variegated plants fertilized with additional nitrogen may change
to all-green. Not certain if this applies to yellow-variegated,
white-variegated, or both.

Judy