The answer to why some Primulina 'Loki's have red stems.

Primulina 'Loki' grown by Joe Palagonia (left front) with red leaf stems

The answer to why some Primulina ‘Loki’s have red stems.

The mystery continues.  I’ve been to several Gesneriad events recently and have collected all the anecdotal evidence I can from expert hobbyists who are thinking about this question.

Theory I:

It’s the temperature ---- cold (below 60 F) brings out the red stems on the leaves.

Counter point:

Red has been seen on plants grown in constant warm (70 F)

Theory II:

It’s from using high lime in the mix for Primulinas.

Counter point:

Then why don’t all the other Primulinas in the collection show red and not just ‘Loki’?

Theory III:

Abnormal red coloring in leaves is a symptom of Phosphorus deficiency.  This could be caused by very low Phosphorus in the fertilizer or from a high Ph that makes Phosphorus unavailable.

Counter:

At least three separate growers have red stem ‘Loki’, so this is unlikely.

Theory IV:

There has been a mutation and there are two clones --- one gets red, the other doesn’t.

Facts as we know them.

The original stock plants came from the same source, Peter Shalit’s‘Loki’ (red) at the 2012 Mid Atlantic Gesneriad Show. A leaf was given to Paul, who has red stems and me who has green stems.  Joe’s plant (red) was derived from Paul’s (red).  All of my 1,000 ‘Loki’s (green) were propagated from that single leaf.

Jim points out that propagations are from a single cell and that mutations can occur there.  Troy points out that mutations are very rare, which makes this unlikely.

The test:

I am propagating a leaf from Joe’s plant (red).  If the plantlets come out red under my conditions then maybe we can say that there are two clones.

Why does any of this matter?

The red stemmed ‘Loki’s are very interesting and potentially a better clone for the Christmas red /green market.

The answer is:

I don’t know.

            Until someone uses the scientific method of changing one variable at a time, we won’t know for sure.  All we can do is to try to piece together antidotes.