Heterophylly in Holly: Science and Season’s Greetings!

Heterophylly in Holly: Science and Season’s Greetings!

⁕  From ancient tree-worshipping Druids to Romans celebrating Saturnalia, from the pagan rituals of Solstice to Hallmark cards of Christmas cheer, the prickly leaves of the Holly (Ilex aquifolium) are a familiar tradition of the season.

⁕  But not all holly leaves are picturesquely prickly. A botanist or gardener knows that the leaves can be smooth or variably serrated, even within a single bush. This is called heterophylly. Scientists took a trip to a forest in southeastern Spain where they noticed a correlation between the grazing pattern of herbivores and the location of prickly leaves- there were more prickly leaves at heights under 2.5 m, the average reach of an adult deer. They then compared the DNA in smooth and prickly leaves from the same plants. Genetically, they were identical, so what explained the difference in appearance? 

Epigenetics is the science that describes how DNA is chemically modified to turn on or off genes. Within the same branch, smooth leaves showed more DNA methylation compared to prickly leaves. These differences were not randomly distributed, but were confined to specific regions of the genome. This suggested that the Holly responded to hungry herbivores by changing which genes were turned on (a process known as transcription) to make more painfully prickly leaves. What’s nice about this swift molecular tit-for-tat is that it does not depend on the slow process of natural selection to respond to immediate pressures in the environment. 

Here’s wishing you Season’s Greetings with this science-y sprig of Holiday Holly!

#ScienceEveryday  when it’s not #ScienceSunday . 

⁕  REF: Epigenetic correlates of plant phenotypic plasticity: DNA methylation differs between prickly and nonprickly leaves in heterophyllous Ilex aquifolium (Aquifoliaceae) trees

Carlos M. Herrera and Pilar Bazaga 


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55 Responses to Heterophylly in Holly: Science and Season’s Greetings!

  1. Interesting.  The next time I stab myself as I pass my holly bush I will not say ” Oh crap”…I will say “Oh epigenetic heterophylly”. 

  2. Rajini Rao says:

    Hear the Hollies sing:

    “Harken all the time has come

    To turn on genes and turn off some”

  3. Rajini Rao says:

    Mark Bothwell do let the Holly know that you are not some grazing herbivore 🙂

  4. Peter Lindelauf Now you have me hearing Burl Ives singing “have a heterophyllic Christmas”.

  5. Very interesting. Trauma induced, rapid genetic response in self defense!

    Happy Holidays Rajini!

  6. Rajini Rao says:

    David Andrews indeed! There is a compound called jasmonic acid that is released during wound signaling in plants: http://jxb.oxfordjournals.org/content/52/354/1.full

  7. mary Zeman says:

    Seasons greetings Rajini Rao !

  8. Rajini Rao says:

    Happy Holly-Days to you, mary Zeman !

  9. Rajini Rao says:

    Thanks, and to you too Jose M. G. Guerreiro! 🙂

  10. Bill Liu says:

    Such a great post for the geneticists on Christmas. Thank you Rajini Rao Hopefully you dont mind I repost this to fb….

  11. All those holly bushes outside and I never paid that much attention (besides how they hurt if I walk into them). It makes sense though now I wonder about other plants. Mulberry leaves have such variety that I wonder the reason. I love posts that that make you think.

    …except I have no good puns. Disappointed right now.

  12. I am also science student

  13. Rajini Rao says:

    Have you heard this holiday pun, Carissa Braun ? It will sleigh you.

    If Santa rode a motorcycle, what kind would it be? A Holly Davidson. 

  14. Rajini Rao says:

    Cheers, and all the best for 2015 to you and your family Ali Adelstein !

  15. Gary Ray R says:

    Thanks Rajini Rao I always learn something interesting from your science based posts. 

    Have a Kool Yule!

  16. Interestingly there is a plant called Osmanthus heterophyllus, or False Holly. According to Wikipedia, “Spiny leaves predominate on small, young plants (an adaptation to deter browsing animals), while entire leaves predominate higher on larger mature plants out of the reach of animals.” http://en.wikipedia.org/wiki/Osmanthus_heterophyllus

    I have sold the plant for years and never knew why it had the name, or the definition of heterophylly. Thanks 🙂


  17. Rajini Rao says:

    How interesting, thanks for the link Trey Pitsenberger . I see that it is also dioecious, like the Holly, with male and female plants. People mistakenly think that the spiny vs. smooth leaves are found on male vs. female plants. 

  18. Merry Christmas, Rajini Rao 

  19. Rajini Rao says:

    Thanks! Merry Christmas and wishing you all the best in 2015, Denis Labelle .

  20. david pitts says:

    Is this explain prickly people?

  21. Rajini Rao says:

    david pitts well, there is evidence for epigenetic modifications and altered gene expression in neuropsychiatric disorders. So, in answer to your question, yes it could explain “prickly” people 🙂


  22. Hmmm…so we are in d holly epigenetic seasons…well i wish u all merry xmas n happy new.

  23. Rajini Rao says:

    crescent augustine  haha, happy epigenetic new year to you. 

  24. Rajini Rao says:

    Rashid Moore thanks! I like this Hollies number too: https://www.youtube.com/watch?v=DFPu83ggTlM

  25. Rajini Rao​,

    A year is coming to an end with another new year in the horizon. What we have accomplished is the reminder for betterment in the future totally acknowledging our feats in life.

    Wishing you and your family, a Blessed and Merry Christmas and a prosperous New Year. May God continue to shower his blessings.

    Love and hugs

  26. Rajini Rao says:

    Jacob Mathews thank you for your kind and generous wishes. I’m indeed looking forward to the new year and wish you all good things in 2015. ❤

  27. Rajini Rao says:

    Thanks, and the same to you Mark Bruce 🙂

  28. Jim Gorycki says:

    Have a Holly Jolly Christmas.  Wait, what rhymes with  heterophyllic ?

  29. Rajini Rao says:

    Their gilding so metallic

    Holly leaves are heterophyllic

    With herbivores in the vicinity

    They show phenotype plasticity

  30. Rajini Rao Thank you for the link! That was great.

    “Most of the induced responses occur in a time window between a few minutes to several hours after wounding, and include the generation/release, perception and transduction of specific signals for the subsequent activation of wound‐related defence genes.”

    Madam, your reach across the disciplines of science impress and inspire me.

    I’m sure I am not alone.  

  31. Rajini Rao says:

    Delighted that you enjoyed the article, David Andrews, and many thanks for your nice words. 

  32. Ha! Good one, Rajini Rao​. Glad you didn’t leave me hanging. I’ll point out that I hadn’t heard that one yet.

  33. Rajini Rao says:

    It wasn’t berry good, I’m afraid Carissa Braun . Perhaps Chad Haney’s wit is sharper than ours. 

  34. Chad Haney says:

    That’s the first time someone has holly at me for a pun.

  35. Rajini Rao says:

    Ilex pect that you won’t beat around the bush Chad Haney.

  36. अनेक जण भेटतात..

    खूप जण आपल्या जवळ येतात

    आणि दुरावतात ही…

    अनेक जन आपल्याला शब्द देतात

    आणि विसरतात ही…

    सूर्यास्ता नंतर स्वताःची सावलीही दूर


    शेवटी आपण एकटेच असतो


    सोबत असतात फक्त आणि फक्त आठवणी

  37. Chad Haney says:

    Um, not sure about that.

  38. I wish you a merry Christmas Rajini Rao !

  39. Rajini Rao says:

    Suhail Manzoor Thanks, I hope you are enjoying a tropical Xmas! It’s cold, wet and dreary here. 

  40. Rajini Rao 

    Happy holidays to you and yours. 🙂

  41. Rajini Rao says:

    Cheers, and the same to you Lilium Candidum !

  42. Kevin Franck says:

    QUOTE: “From ancient tree-worshipping Druids to Romans celebrating Saturnalia, from the pagan rituals of Solstice to Hallmark cards of Christmas cheer, the prickly leaves of the Holly (Ilex aquifolium) are a familiar tradition of the season.”


    Yep, oddly enough this is why I have not celebrating Christmas since the late 1960s. Most people in Christendom are totally ignorant or oblivious to the historicity if this holiday’s origins which don’t even remotely originate with their Holy Book. Not that I am against gift giving, getting together with family and friends or any other such noble practices, but not just once a year. We practice such things all year and save massive amounts of money in the process. 

    Now aside from this, I find epigenetics to be fascinating study of mechanisms devoid of the the religiosity surrounding random mutations and natural selection which I find comparable and quite realistically a mirror  to most of the creationist explanations which require blind faith. Epigenetics actually helps to open up the door to actual mechanisms which we all can sink our teeth into as opposed to much of the usual storytelling that science can often be shackled to. Hopefully this part of scientific research will put to rest the religious view of Junk DNA which has done more harm to our understanding of DNA than has shed light on it. Look, I don’t like many of the Fundie beliefs either, but I refuse to align myself along side another failed religious blind faith because Science may not know function of certain DNA. This is a major reason we have GMOs which are based on “Bad Designer” arguments which have allowed this flawed view that nature itself is the bad designer and imperfect. In all my years in working with habitat restoration and landscape design and maintenance, I have never found this to be true. 

    Hence, 150+ years of scientific enlightenment has brought the Earth’s natural world to it’s knees. Unlike many of those articles which were published back in 2012  about this subject of Phenotypic Plasticity & Holly suggested at the very end of those articles, no amount of epigenetics is going to save the natural world from the  artificial unnatural world bad science is creating which we call Climate Change. Still, for everyone here, look up and pay close attention to the work being done with Epigenetics and the ENCODE Project which will hopefully shed more important light on the Non-Coding DNA (Junk DNA for those with a religious ax to grind) and the potential benefits from respecting the amazing complex way life should be defined by it’s informational content as opposed to the material substrate it is made of. 

    Again, I thoroughly enjoyed the article. Thanks for posting.

  43. Happy holidays Rajini Rao .

  44. Jim Gorycki says:

    Rajini Rao by George you got it!

  45. llany59 says:

    Gracias Rajini por tu estudio y observación de las características físicas del acebo. Personalmente  no estaba al tanto de su historia la cual es bastante interesante.   Personalmente en el patio de mi casa  tengo en una maceta de greda un árbol  de acebo. la forma de sus hojas se asemejan a la quinta hoja de muestra y en su punta en mas fina y larga dando una forma estilizada y elegante a cada hoja, pienso que es algo peculiar la forma de las hojas de este arbusto en el cono sur de américa , mejor dicho en Chile.  

  46. Mc Chakiri says:

    Thanks again for your business, and I have had the chance of winning a bit

  47. Alex J says:

    Wow, absolutely amazing page! It’s easy to see how you have over 250k followers. 😀 THANK YOU.

  48. Rajini Rao says:

    Alex J , I’m so glad you enjoyed this one..thanks! 🙂

  49. This is definite sign I’m never too old to learn- thanks for sharing.

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