Question: Explain Variegation in Ivy (xv): testing the theory: predicting streaked variegation

Streaked variegation, as opposed to the two former patterns, leaves a more irregular marking on a leaf. The almost mathematical patterns of a periclinal chimera tells us a streaked pattern must have a different cause.

When a layer has normal cells and a population of mutated cells (developing albino chloroplasts) the plant is called a mericlinal chimera. When the population of mutated cells covers more than one layer (still having normal cells) the plant is called a sectional chimera.

Entire yellow or green shoots are more likely to develop (as opposed to periclinal chimeras). The amount of mutated cells contributing sections of the leaf is unpredictable. To understand this you have to know a little about leaf initiation. This is the subject of the next post.