Photochromic reverse, anyways

I’m liking the bright yellow to deep red effect that this blossom is showing.

Forgive me, this is my second flower of the year so I’m paying close attention.

For any newbies, what I’m calling photochromism is an effect where the blossoms change color in response to sunlight. On this bud the yellow part is the base color that just emerged from behind the sepals.

Campfire and Music Box are two commercial roses that exhibit such an effect.

The petals usually turn pink. I’ve had one seeding (RIP, skid steer blight) that went from yellow to basically red. I’m hoping the same for this one! I have no idea if the effect is usually the same for the front and reverse of the petals.


I share your delight!

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I have the same effect, to varying degrees, going on with three seedlings this year (all from the same cross). The attached picture shows a blossom where I deliberately shaded the right side as it opened,

and it remained mostly yellow.

My first impression is that the light exposure has a short window as the bloom unfurls to turn a petal to red. I haven’t really looked at the available literature. After it is fully open, I think there is little change.


The timing of coloration seems to vary with the cultivar. Some are more sensitive to sunlight, some color both sides of the petal. If the yellow fades, the effect is different from when it holds on. My impression is that tings tend more toward simpler pink if the yellow goes, but may stay closer to red/scarlet if it stays. Not to disappoint you, but I’ve had a lot of buds show red on back of petals as sepals separate, but the color never extends all over the back or front of petals, just that brief, transitory red on back. My foray into Italian Ice open pollinated selections is a a good example of this. Lee’s photo on the pink side is like an older II… Several decades ago I had some minis that did this really well. In my greenhouse in winter, just yellow, outside in summer, changing to red over several days. IIRC they came from Nor’East and were bred there.

Thank you for the insight. Here are pictures of a hip-sibling, and the
petal tops turned from yellow to a veined pinkish red very quickly as it opened on all areas exposed to light. However, the reverse remained yellow…but I’m not certain if that’s because the reverse isn’t photochromic, or simply because it wasn’t exposed to light. Any thoughts?

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