See It with Flowers: A BioSensor for Radiation

See It with Flowers: A BioSensor for Radiation

✿ The stamen hairs of the common spiderwort (Tradescantia) are made up of rows of cells in single file, like beads on a string. Fuzzy and blue, they emerge by the hundreds around the stamens that hold up the bright yellow, pollen-filled anthers in the flower center. In 1975, a scientist named Sparrow made a remarkable discovery: the stamen hairs were highly sensitive to nuclear radiation, mutating from blue to pink like the floral equivalent of the canary in the coal mine! The mutation frequency is linear down to very low doses and low exposure rates such that counting the number of pink cells as a percentage of blue ones gives an accurate reading of radiation exposure. Since the cells divide in sequence, the position of the pink cell tells when the radiation exposure occurred. The flowers have been used to monitor radiation leaks around nuclear plants in Japan or as a biosensor for chemical pollutants (

✿ As if this biological oddity were not enough, the flower enjoys a romantic history dating to Captain John Smith, the legendary American settler who was plucked from the perils of death at the hands of the Powhotan tribe by the chief’s daughter Pocohontas. When Smith left Virginia in 1609, he carried with him spiderwort seeds to his friend John Tradescant the Elder, a master gardener in England. The plant was named Tradescantia virginiana in the latter’s honor (

Image Credits: Tradescantia from the garden of Chris Veerabadran whose question about the flower name inspired this post. Thanks, Chris! 

Staminal Hair from

Video: Cytoplasmic Streaming in Tradescantia Stamen Hair Cells


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47 Responses to See It with Flowers: A BioSensor for Radiation

  1. Kathryn Kure says:

    Great post! So happy to see you posting again :D.

  2. Fascinating! I’ll be inspecting our tradescantia more closely now – can hardly wait for it to bloom 🙂

  3. Rajini Rao says:

    Hello there, Kathryn Kure . Any time I need inspiration to post, I can look at your flower posts 🙂

  4. Rajini Rao says:

    Hudson Ansley , your garden version should be all blue, hopefully. The varieties used for testing do have to be heterozygous at the color locus i.e., one copy coding blue and the other pink. Blue is dominant over pink, but damaging mutations allow the pink to reveal itself. 

  5. Marta Rauch says:

    Fascinating! Thanks so much for sharing this with us, Rajini Rao. 

  6. Rajini Rao says:

    You’re welcome, Marta Rauch . Thanks, Martha Maxwell 🙂

  7. ma’am why does anesthesia when employed to touch me not plant in bell chamber does not show any stimuli ?

  8. Tau-Mu Yi says:

    Wow more fascinating Science that I was not aware of!

  9. jackie says:

    Dawn Hart Jackson I thought you might find this interesting considering the pic you shared yesterday.

  10. and like humans we measure nerve impulses by EMG and like this can we control these plants

  11. Rajini Rao says:

    Dhaya kumar anesthetics probably inhibit the ion channels that are required for electrical signaling in the touch me not plant. 

  12. Tim Mousseau will like this. 

  13. I love these. Plants are incredible.

  14. Rajini Rao says:

    Hey, Hilah Johnson . What’s cooking? I love flowers too 🙂

  15. nizar M H says:

    hii Rajini how r u

    Sent from Windows Mail

  16. Rajini Rao says:

    Too early for blooms here in Maryland, Peter Lindelauf . 

  17. Rajini Rao I actually got my bachelors degree in botany. 🙂 I never use it, of course, but I still love learning about the minuscule miracles that go on inside plant cells. 

  18. Rajini Rao says:

    That’s awesome, Hilah Johnson ! Delighted that we share a love for botany and cooking 🙂

    BTW, I gave your cookbook to my grad student as a farewell gift. Hopefully, she is cooking with it.

  19. Rajini Rao  Now, I need to water and take care of them even more, amazing plant 🙂 To see their usefulness of Science is great, shows how important every plant and animal is and how we need to guard them.

  20. Rajini Rao says:

    Very true, Chris Veerabadran 🙂

  21. Tim Mousseau says:

    Very cool. I like it.

  22. Mary T says:

    Very cool ~ flowers, radiation, and history all in one great post :-).

  23. Wow, I learned something new for #floralfriday. Thanks!

  24. Rajini Rao Thank you so much! Gosh, that makes me so happy. 😀

  25. querida. que bela reportagem. amei; me mande sempre. obrigado.

  26. It makes me think of tree rings but on a far smaller scale. Very cool post Rajini Rao!

  27. Rajini Rao says:

    Carissa Braun apparently the pink/blue is easy enough to score that thousands of stamen hairs were counted by high school students.  

  28. Those grow wild in my garden!! I didn’t know what they were! Now I love them even more!! Very interesting info!!

  29. Rajini Rao says:

    Pretty neat, isn’t it rebecca meyers . I’d like to imagine there is as story to tell behind every ordinary plant that would make us look at it with fresh eyes. 

  30. Adit Morey says:

    It’s very interesting to know that the color change response of the common spiderwort to nuclear radiation can be used to monitor radiation leaks…thanks for sharing Proff. Rao.

  31. very interesting, does anyone know the mechanism of interaction between radiation and molecules that build the cell that make it happen?

  32. Rajini Rao says:

    Narayana Wijaya , the color of the stamen hair cells is based on a single gene that comes in two versions or alleles, blue and pink. The blue allele is dominant over pink. The flowers chosen for this experiment have to be heterozygous at this gene locus, i.e., one allele is blue and the other pink. The idea is that radiation damages DNA indiscriminately. There is a certain chance that gamma/x rays/neutrons hit the blue gene version and damages it. With the blue knocked out of commission, the pink version reveals itself. Of course, the pink gene could also be damaged but we would not be able to see a difference by looking at the cells. Many other genes could also be damaged, but the blue is like a marker for the rest. 

    Hope this makes sense, let me know if you have questions! 

  33. Rajini Rao says:

    Phillip Buckhaults thanks for the link. I’m adding Tim Mousseau to my circles 🙂

    I only stumbled on the topic myself. BTW, hello from Hopkins (were you with the Vogelstein group?). 

  34. Hello to Hopkins from UAB, (affectionately known as Hopkins-Y’all).  Yes, i am indeed a Vogelfam member. 

  35. Rajini Rao says:

    Great to link up with you here. Let me know if you come to B’more for a visit. 

  36. Truly amazing! Thanks for sharing Rajini Rao . Are there any other flowers showing such activity, tropical flowers that you know of, or is it a very rare property?

  37. Rajini Rao says:

    Hi Siromi Samarasinghe . Glad you enjoyed this. I suspect many other species could be used in a similar way. What works here, is that the staminal cells are single file, and in active mitosis. So the chromosomes are susceptible to radiation damage and the color change is easy to score using a cheap light microscope. It turns out that pollen cells are an even more sensitive test of radiation damage- they accumulate broken nuclei or micronuclei, but this involves more careful analysis. 

  38. Thanks, it is quite clear explanation. The problem only because I don’t understand the biological term which will rise too many basic question around them.

  39. I already have a canary, I may want to have this plant as well. Fascinating. Thank you for sharing Rajini Rao 

  40. Super rajini hadwark

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