siberian iris changed color

Question

I received a set of Siberian irises from my mother-in-law about 27 years ago. Hers were white as far back as I remember. I transplanted them to our home, then to an apartment for a summer, then to our new house (16 years ago). They have always been white. I thinned the patch out last year and moved a few roots to the front of the house. The white ones bloomed about 3 weeks ago, and yesterday the front ones bloomed – only BRIGHT yellow! Nothing pale or bashful about that color. I love it.

My question is why? There was some round-up sprayed near there but not on the plant. It does get more shade, northwest exposure versus southeast. I have pictures if you would like to see them.

Thank you!
Mary McNeill [e-mail]

Answer 1

Iris do not change color, but growing conditions can make colors more or less vibrant.
Over spray of a herbicide have been reported to change colors temporarily.
Iris can actually drop seed and sprout new flowers that may not be true to the parent flower due to bee pollination from other iris color.
It is reported that their are a few varieties that will ‘sport’ and new color.
The variety Honorabile has a history of this rare event.
It is also possible that a garden area had previous rhizomes and you had original yellow Iris that had never bloomed until they were lifted and moved.