Foxglove (Digitalis purpurea monstrosa) Forms Peloric Flowers

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Robert Pavlis

I walked outside a few days ago and immediately spotted my monster foxglove. It is a cream yellow, growing in a fairly shady spot where the color just glows. But what made it really stand out is the large uncharacteristic flower at the top of the inflorescence (flower stem).

After a bit of work on the computer, I learned that this is a rare peloric mutation.

Foxglove (Digitalis purpurea monstrosa) forms peloric flowers, by Robert Pavlis
Foxglove (Digitalis purpurea monstrosa) forms peloric flowers, by Robert Pavlis

Peloric Flowers in Foxglove

The formation of peloric flowers in foxgloves is fairly rare but they have been report for many years. The proper botanical name for this plant is Digitalis purpurea monstrosa. The term monstrosa is Greek and means huge or monsterous.

A normal foxglove develops an indeterminate inflorescence that steadily gets taller until the plant can’t support more flowers. The flowers open sequentially starting at the bottom. In a peloric foxglove, a terminal flower develops and opens before any of the other buds. This stops any further growth above the peloric flower. The remaining flowers open from the bottom up and have a normal shape.

Closeup of foxglove peloric flower, by Robert Pavlis
Closeup of foxglove peloric flower, by Robert Pavlis

A normal foxglove flower has bilateral symmetry, where the left side mirrors the right side through a vertical axis. The peloric flower shows radial symmetry. You can draw any number of axis through the flower and the two halves mirrors each other, provided that the flower developed properly.

Plant Science for Gardeners by Robert Pavlis

Pelorism is normally found in plants that have a bilateral symmetry, such as gloxinia, orchid, snapdragon, Pelargonium, Primula auricula and members of the mint family.

Genetics of Pelorism

The genetics of peloric foxgloves was deciphered a hundred years ago. It is controlled by a simple Mendelian recessive gene. If you cross a peloric plant with itself, all of offspring will be peloric. If this plant is crossed with a fully normal plant, all of the F1 offspring (first generation) will look normal, but will carry the recessive gene, which is expressed in the F2 generation.

The expression of the gene is a bit more complicated than that because peloric plants don’t always form the top peloric flower, in which case they look quite normal. It is not clear what causes the expression of the gene, but the environment is referenced by several people. It could be a decrease in light, or unusual temperatures, indicating an epigenetic effect.

All of the flowers on a peloric plant, including the top one, will produce seed that contains the recessive gene.

History of the Monster Foxglove

Peloric foxglove showing a more typical coloration
Peloric foxglove showing a more typical coloration

So where did my plant come from? I had been growing some hybrid D. purpurea nearby but since they are biennial and I mulch heavily, foxgloves tend not to self sow very much. A few did flower in the same spot as the peloric one, but they did not show pelorism, nor were they a creamy yellow color with almost no spotting.

D. lutea, a reliable perennial in my garden also flowers close by. It is yellow, but much smaller in size. I also grow D. lanata and D. grandiflora on the other side of the house. Cross pollination was certainly possible.

Building Natural Ponds book, by Robert Pavlis

This year, the plant in the picture is the only D. purpurea that is flowering in the garden so cross pollination is not likely within the species.

The subject plant has made four flowering stems so far, and each is topped with a peloric flower. It is the only fully yellow one that I found on the internet.

This is the first peloric plant I have seen in the garden, and the weather this year has been very unusual. It has been very cold and wet. It is middle June, and normal late spring weather has still not arrived, causing many plants to behave differently this year.

Peloric Orchids

This adventure brought back memories of growing peloric phalaenopsis orchids, many years ago.

Peloric orchid, Phalaenopsis Vio Vio
Peloric orchid, Phalaenopsis Vio Vio

References:

  1. Photo of peloric orchid; mcgarrett88
  2. Photo of pink peloric foxglove; Dr Mary Gillham Archive Project

 

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

9 thoughts on “Foxglove (Digitalis purpurea monstrosa) Forms Peloric Flowers”

  1. 6/23 i just found in my garden. Mine is even stranger, peloric blossom mid stem and not symmetrical. Wish I could attach photo. I have 4 stems each with one peloric midway up & normal tubular above and below

    Reply
  2. Thanks for this post I’m a gardener and I’d never seen this until yesterday and iv had foxgloves over 45 years and got my first peloric foxgloves show up and looked it up on the Internet which sent me here. Thanks

    Reply
  3. I have just found a foxglove just like this in my garden. Can we collect seeds from this? Will it come again next year?

    Reply
    • That is timely. This post was written 2 years ago. I collected seed from mine, and that seed is just flowering – and all of the seedlings are peloric.

      Reply
  4. I found one of these in my garden recently and had to look it up online. What a curiosity! Thanks for this informative article.

    Reply
  5. Hi I have just found your post as I have a foxglove growing in my garden which has a single different flower on the top. I have never seen this before but found your post as I was trying to find out why the plant is like this. Thanks for the information.

    Reply
  6. Thanks very much for this information, I have never heard of it before, always something new in the gardens to make us curious.

    Reply
    • thanks. I’ve a peloric foxglove growing to beat the band out in my garden and touight it was unique until I began reading about an nomalous foxglove. Glad to know what it is, althoiugh I’m still not sure what caused it.

      Reply

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